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Nakao, Yuki, Hiroyuki Yamada, and Nagahisa Ogasawara. "Deformation and fracture properties of pure ice through impact indentation testing." EPJ Web of Conferences 250 (2021): 06005. http://dx.doi.org/10.1051/epjconf/202125006005.
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The deformation and fracture properties of ice have attracted considerable research interest. The tip shape of an object that comes into contact with the ice may affect the fracture phenomenon of ice, but these mechanisms have not been elucidated. In previous study, we experimentally showed that the shape of the indenter has a significant effect on pure ice deformation and fracture properties by quasi-static indentation testing. In this study, we focus on the impact fracture of pure ice to clarify the effect of strain rate on deformation and fracture phenomena. The impact indentation test was conducted using direct impact Hopkinson bar method, and a spherical indenter with a diameter of 9 mm was attached to the tip of the striking bar. The indentation rate was approximately 2.3 m/s, and the test temperature was approximately -10°C. It was clear that the maximum load of the load–displacement relationship was larger than that of the quasi-static indentation testing. This tendency was qualitatively consistent with the compressive strength of the uniaxial compression testing.
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Grujicic, M., JS Snipes, and S. Ramaswami. "Multi-scale computational analysis of the nano-indentation and nano-scratch testing of Kevlar® 49 single fibers." Proceedings of the Institution of Mechanical Engineers, Part L: Journal of Materials: Design and Applications 232, no. 6 (2016): 495–513. http://dx.doi.org/10.1177/1464420716635851.
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To carry out virtual nano-indentation and nano-scratch Kevlar® 49 single-fiber tests, a multi-scale computational framework has been developed and employed. Such tests are generally conducted to determine fiber local properties, as well as to provide some insight into the interaction of hard nano-particles with the fibers. The Kevlar® fabric-based soft armor is infused with these nano-particles for improved ballistic resistance, and tip geometry of the nano-indentation/-scratch probes is selected to match nano-particle size and geometry. Due to the fact that Kevlar® 49 fibers (typical diameter 12 µm) are effectively assemblies of parallel fibrils (typical diameter 100–300 nm), while atomic bond length in Kevlar® fibers is of the order of 0.2 nm, a continuum-level finite-element framework has been developed. However, to more accurately account for some of the key aspects of the fiber-material constitutive behavior, e.g. inter-fibril cohesion, the continuum-level computational analysis has been supplemented with atomic-level molecular-statics/-dynamics calculations. In good agreement with their experimental counterparts, the results obtained revealed that the extent of participation of different fibril-deformation modes (e.g. transverse compression, inter-fibril shear, axial tension, axial tensile fracture, fibrillation, axial compression, buckling and pile-up formation ahead of the nano-scratch probe, etc.) is a function of the indentation/scratch depth. Also, a relatively good agreement was obtained between the computed and experimentally measured nano-indentation forces/energies for both shallow and deep indentations, and for the nano-scratch forces/energies, but only for shorter scratch lengths. At longer scratch lengths, the “short-fiber” effects cause the computation/experiment agreement to worsen.
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Idris, Maizlinda I., Tania Vodenitcharova, and Mark Hoffman. "Resistance of Thin Al Foam Panels to Deep Indentation." Materials Science Forum 561-565 (October 2007): 357–60. http://dx.doi.org/10.4028/www.scientific.net/msf.561-565.357.
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In recent years there has been a considerable amount of research into the deformation behaviour of metallic foams. The majority of this research has only addressed size-independent bulk material properties, obtained through uniaxial compression and indentation tests of thick blocks. There is little information in the literature on the indentation response of thin panels, which has motivated the current study. Thin panels of ALPORAS closed-cell foam of ~ 0.25 g/cm3 density were tested in uniaxial compression, and were indented with long flat-plate punches and long cylindrical punches. Cross-sectioning of the samples following interrupted testing revealed the plastic strain evolution process. The deformation was attributed to the progressive crushing of the cell bands, and the combined action of shearing and tearing resistance. Based on energy formalism, a model was developed to estimate the crushing force. By fitting the experimental loaddisplacement curves, the foam ligament tearing energy was deduced for all types of indentation. The absorbed energy was also calculated for the uniaxial compression and indentation experiments.
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Dias, A. M. S., and G. C. D. Godoy. "Determination of Stress-Strain Curve through Berkovich Indentation Testing." Materials Science Forum 636-637 (January 2010): 1186–93. http://dx.doi.org/10.4028/www.scientific.net/msf.636-637.1186.
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Instrumented indentation testing is a technique widely used in different materials to evaluate the penetration depth in function of the indenter load. Considering Berkovich indenter, this methodology has been used to determine mechanical properties such as hardness, Young modulus and a stress versus strain curve of the elastic-plastic behaviour under compression of the tested materials. However, the implementation of this technique to evaluate mechanical properties and also its results have still brought doubts on research areas. Nowadays, the use of a numerical methodology able to evaluate the stress and strain fields during indentation cycle can lead to a more secure interpretation. The aim of this work was to simulate the Berkovich indentation testing and to propose a methodology to extract the stress-strain curve through experimental and numerical analyses. The obtained numerical results for the load-displacement curve were quite similar to the experimental curve presented in the literature.
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SHIMIZU, Yuta, and Hiroyuki KATO. "Micro-instrumented indentation testing of plate aluminum under tension/compression load." Proceedings of Conference of Hokkaido Branch 2018.56 (2018): 312. http://dx.doi.org/10.1299/jsmehokkaido.2018.56.312.
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Affolter, Christian, Götz Thorwarth, Ariyan Arabi-Hashemi, Ulrich Müller, and Bernhard Weisse. "Ductile Compressive Behavior of Biomedical Alloys." Metals 10, no. 1 (2019): 60. http://dx.doi.org/10.3390/met10010060.
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The mechanical properties of ductile metals are generally assessed by means of tensile testing. Compression testing of metal alloys is usually only applied for brittle materials, or if the available specimen size is limited (e.g., in micro indentation). In the present study a previously developed test procedure for compressive testing was applied to determine the elastic properties and the yield curves of different biomedical alloys, such as 316L (two different batches), Ti-6Al-7Nb, and Co-28Cr-6Mo. The results were compared and validated against data from tensile testing. The converted flow curves for true stress vs. logarithmic strain of the compressive samples coincided well up to the yield strength of the tensile samples. The developed compression test method was shown to be reliable and valid, and it can be applied in cases where only small material batches are available, e.g., from additive manufacturing. Nevertheless, a certain yield asymmetry was observed with one of the tested 316L stainless steel alloys and the Co-28Cr-6Mo. Possible hypotheses and explanations for this yield asymmetry are given in the discussion section.
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Cao, Li, Inchan Youn, Farshid Guilak, and Lori A. Setton. "Compressive Properties of Mouse Articular Cartilage Determined in a Novel Micro-Indentation Test Method and Biphasic Finite Element Model." Journal of Biomechanical Engineering 128, no. 5 (2006): 766–71. http://dx.doi.org/10.1115/1.2246237.
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The mechanical properties of articular cartilage serve as important measures of tissue function or degeneration, and are known to change significantly with osteoarthritis. Interest in small animal and mouse models of osteoarthritis has increased as studies reveal the importance of genetic background in determining predisposition to osteoarthritis. While indentation testing provides a method of determining cartilage mechanical properties in situ, it has been of limited value in studying mouse joints due to the relatively small size of the joint and thickness of the cartilage layer. In this study, we developed a micro-indentation testing system to determine the compressive and biphasic mechanical properties of cartilage in the small joints of the mouse. A nonlinear optimization program employing a genetic algorithm for parameter estimation, combined with a biphasic finite element model of the micro-indentation test, was developed to obtain the biphasic, compressive material properties of articular cartilage. The creep response and material properties of lateral tibial plateau cartilage were obtained for wild-type mouse knee joints, by the micro-indentation testing and optimization algorithm. The newly developed genetic algorithm was found to be efficient and accurate when used with the finite element simulations for nonlinear optimization to the experimental creep data. The biphasic mechanical properties of mouse cartilage in compression (average values: Young’s modulus, 2.0MPa; Poisson’s ratio, 0.20; and hydraulic permeability, 1.1×10−16m4∕N‐s) were found to be of similar orders of magnitude as previous findings for other animal cartilages, including human, bovine, rat, and rabbit and demonstrate the utility of the new test methods. This study provides the first available data for biphasic compressive properties in mouse cartilage and suggests a promising method for detecting altered cartilage mechanics in small animal models of osteoarthritis.
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Lin, David C., Emilios K. Dimitriadis, and Ferenc Horkay. "Robust Strategies for Automated AFM Force Curve Analysis—I. Non-adhesive Indentation of Soft, Inhomogeneous Materials." Journal of Biomechanical Engineering 129, no. 3 (2006): 430–40. http://dx.doi.org/10.1115/1.2720924.
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The atomic force microscope (AFM) has found wide applicability as a nanoindentation tool to measure local elastic properties of soft materials. An automated approach to the processing of AFM indentation data, namely, the extraction of Young’s modulus, is essential to realizing the high-throughput potential of the instrument as an elasticity probe for typical soft materials that exhibit inhomogeneity at microscopic scales. This paper focuses on Hertzian analysis techniques, which are applicable to linear elastic indentation. We compiled a series of synergistic strategies into an algorithm that overcomes many of the complications that have previously impeded efforts to automate the fitting of contact mechanics models to indentation data. AFM raster data sets containing up to 1024 individual force-displacement curves and macroscopic compression data were obtained from testing polyvinyl alcohol gels of known composition. Local elastic properties of tissue-engineered cartilage were also measured by the AFM. All AFM data sets were processed using customized software based on the algorithm, and the extracted values of Young’s modulus were compared to those obtained by macroscopic testing. Accuracy of the technique was verified by the good agreement between values of Young’s modulus obtained by AFM and by direct compression of the synthetic gels. Validation of robustness was achieved by successfully fitting the vastly different types of force curves generated from the indentation of tissue-engineered cartilage. For AFM indentation data that are amenable to Hertzian analysis, the method presented here minimizes subjectivity in preprocessing and allows for improved consistency and minimized user intervention. Automated, large-scale analysis of indentation data holds tremendous potential in bioengineering applications, such as high-resolution elasticity mapping of natural and artificial tissues.
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Chen, Xingyu, Yilu Zhou, Liyun Wang, Michael H. Santare, Leo Q. Wan, and X. Lucas Lu. "Determining Tension–Compression Nonlinear Mechanical Properties of Articular Cartilage from Indentation Testing." Annals of Biomedical Engineering 44, no. 4 (2015): 1148–58. http://dx.doi.org/10.1007/s10439-015-1402-8.
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Lee, Moon Kyu, Kui Won Choi, Tae Soo Lee, and H. N. Lim. "Evaluation of Indentation Test for Measuring Young’s Modulus of Cancellous Bone." Materials Science Forum 544-545 (May 2007): 307–10. http://dx.doi.org/10.4028/www.scientific.net/msf.544-545.307.
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The indentation test has been in the spotlight due to easy and non-destructive testing characteristics. However, there are little studies for the indentation test of porous materials in the evaluation aspect of methodology. The goal of this study was to evaluate a spherical indentation test in the aspect of indenter-size and indentation depth by measuring elastic modulus of porous materials such as a cancellous bone using a FEM. We developed a microstructure-based FE model of cancellous bone with apparent density 0.2~0.8 g/cm3 in order to simulate uniaxial compression test and indentation test in the light of anatomical observation with a scanning electron microscope (SEM). We obtained a load-displacement curve through the indentation simulation and calculated the Young’s modulus of cancellous structure based on Pharr's hypothesis. The result indicated that indenter diameter has to be more than five times of pore size and indentation depth should be about 8% of indenter diameter at least to obtain the appropriate result of the indentation test. It is expected that this result may guide to the design and the simulation of indentation test for porous materials
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Zobitz, Mark E., Zong-Ping Luo, and Kai-Nan An. "Determination of the Compressive Material Properties of the Supraspinatus Tendon." Journal of Biomechanical Engineering 123, no. 1 (2000): 47–51. http://dx.doi.org/10.1115/1.1339816.
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A methodology was developed for determining the compressive properties of the supraspinatus tendon, based on finite element principles. Simplified three-dimensional models were created based on anatomical thickness measurements of unloaded supraspinatus tendons over 15 points. The tendon material was characterized as a composite structure of longitudinally arranged collagen fibers within an extrafibrillar matrix. The matrix was formulated as a hyperelastic material described by the Ogden form of the strain energy potential. The hyperelastic material parameters were parametrically manipulated until the analytical load-displacement results were similar to the results obtained from indentation testing. In the geometrically averaged tendon, the average ratio of experimental to theoretical maximum indentation displacement was 1.00 (SD: 0.01). The average normalization of residuals was 2.1g (SD: 0.9g). Therefore, the compressive material properties of the supraspinatus tendon extrafibrillar matrix were adequately derived with a first-order hyperelastic formulation. The initial compressive elastic modulus ranged from 0.024 to 0.090 MPa over the tendon surface and increased nonlinearly with additional compression. Using these material properties, the stresses induced during acromional impingement can be analyzed.
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Xu, B. X., and Z. F. Yue. "Study of the ratcheting by the indentation fatigue method with a flat cylindrical indenter: Part I. Experimental study." Journal of Materials Research 21, no. 7 (2006): 1793–97. http://dx.doi.org/10.1557/jmr.2006.0222.
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Generally, ratcheting is studied on round specimens under tension–compression tests with a nonzero mean load. This work explored the possibility of studying ratcheting by indentation fatigue with a flat cylindrical indenter. In the experiment, emphasis was concentrated on the influence of maximum indentation load (Pmax.), indentation load variance (ΔP = Pmax − Pmin) and frequency of cycling (f) on the indentation depth–cycle curves. The experimental results showed that the indentation depth–cycle curves are analogous to the conventional strain–cycle curve of uniaxial fatigue testing, which has a primary stage of decaying indentation depth per cycle followed by a secondary stage of nearly constant rate of indentation depth per cycle. It was found that the steady-state indentation depth per cycle is an approximate linear function of maximum indentation load (Pmax) and indentation load variance (ΔP = Pmax − Pmin) in the log–log grid. This relationship can be given with a power-law expression as an analogous equation of steady-state ratcheting rate. Further study showed that the influence of frequency of cycling on the steady state indentation depth per cycle can be ignored when the frequency of cycling exceeds a certain value. Finally, comparison was made between the conventional uniaxial fatigue test and indentation fatigue test for the steady-state stage. It was shown that the conventional uniaxial fatigue parameters can be obtained by the indentation fatigue method.
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Jin, Hui, and Jack L. Lewis. "Determination of Poisson’s Ratio of Articular Cartilage by Indentation Using Different-Sized Indenters." Journal of Biomechanical Engineering 126, no. 2 (2004): 138–45. http://dx.doi.org/10.1115/1.1688772.
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Articular cartilage is often characterized as an isotropic elastic material with no interstitial fluid flow during instantaneous and equilibrium conditions, and indentation testing commonly used to deduce material properties of Young’s modulus and Poisson’s ratio. Since only one elastic parameter can be deduced from a single indentation test, some other test method is often used to allow separate measurement of both parameters. In this study, a new method is introduced by which the two material parameters can be obtained using indentation tests alone, without requiring a secondary different type of test. This feature makes the method more suitable for testing small samples in situ. The method takes advantages of the finite layer effect. By indenting the sample twice with different-sized indenters, a nonlinear equation with the Poisson’s ratio as the only unknown can be formed and Poisson’s ratio obtained by solving the nonlinear equation. The method was validated by comparing the predicted Poisson’s ratio for urethane rubber with the manufacturer’s supplied value, and comparing the predicted Young’s modulus for urethane rubber and an elastic foam material with modulii measured by unconfined compression. Anisotropic and nonhomogeneous finite-element (FE) models of the indentation were developed to aid in data interpretation. Applying the method to bovine patellar cartilage, the tissue’s Young’s modulus was found to be 1.79±0.59MPa in instantaneous response and 0.45±0.26MPa in equilibrium, and the Poisson’s ratio 0.503±0.028 and 0.463±0.073 in instantaneous and equilibrium, respectively. The equilibrium Poisson’s ratio obtained in our work was substantially higher than those derived from biphasic indentation theory and those optically measured in an unconfined compression test. The finite element model results and examination of viscoelastic-biphasic models suggest this could be due to viscoelastic, inhomogeneity, and anisotropy effects.
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Minnert, Christian, Hamad ur Rehman, and Karsten Durst. "Thermally activated dislocation mechanism in Mo studied by indentation, compression and impact testing." Journal of Materials Research 36, no. 12 (2021): 2397–407. http://dx.doi.org/10.1557/s43578-021-00126-4.
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Abstract Body-centered cubic metals like molybdenum and tungsten are interesting structural materials for high-temperature applications. These metals, are however, brittle at low homologous temperature, caused by the limited mobility of screw dislocations. In this study, the thermally activated deformation mechanisms in bcc Mo have been investigated using strain rate jump nanoindentation and compression tests as well as Charpy V-notch impact testing. The material shows a significant softening with increasing temperature and a maximum in strain rate sensitivity is found at the critical temperature, before decreasing again in the ductile regime. The activation volume, however, showed a distinct increase from about 5 b3 at the onset of the brittle to ductile transition temperature. Here we propose to use temperature-dependent nanoindentation strain rate jump testing and the activation volume as a complementary approach to provide some indication of the brittle to ductile transition temperature of bcc metals. Graphic Abstract
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Desai, C. C., and M. S. V. Ramana. "Vickers micromechanical indentation and compression testing of ferroelectric lead hydrogen phosphate single crystals." Journal of Materials Science 23, no. 2 (1988): 617–20. http://dx.doi.org/10.1007/bf01174695.
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Murthy, Tejas G., Christopher Saldana, Matthew Hudspeth, and Rachid M'Saoubi. "Deformation field heterogeneity in punch indentation." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 470, no. 2166 (2014): 20130807. http://dx.doi.org/10.1098/rspa.2013.0807.
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Plastic heterogeneity in indentation is fundamental for understanding mechanics of hardness testing and impression-based deformation processing methods. The heterogeneous deformation underlying plane-strain indentation was investigated in plastic loading of copper by a flat punch. Deformation parameters were measured, in situ , by tracking the motion of asperities in high-speed optical imaging. These measurements were coupled with multi-scale analyses of strength, microstructure and crystallographic texture in the vicinity of the indentation. Self-consistency is demonstrated in description of the deformation field using the in situ mechanics-based measurements and post-mortem materials characterization. Salient features of the punch indentation process elucidated include, among others, the presence of a dead-metal zone underneath the indenter, regions of intense strain rate (e.g. slip lines) and extent of the plastic flow field. Perhaps more intriguing are the transitions between shear-type and compression-type deformation modes over the indentation region that were quantified by the high-resolution crystallographic texture measurements. The evolution of the field concomitant to the progress of indentation is discussed and primary differences between the mechanics of indentation for a rigid perfectly plastic material and a strain-hardening material are described.
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Shojaei, Pouya, Riccardo Scazzosi, Mohamed Trabia, et al. "An Approach for Material Model Identification of a Composite Coating Using Micro-Indentation and Multi-Scale Simulations." Coatings 12, no. 1 (2022): 92. http://dx.doi.org/10.3390/coatings12010092.
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While deposited thin film coatings can help enhance surface characteristics such as hardness and friction, their effective incorporation in product design is restricted by the limited understanding of their mechanical behavior. To address this, an approach combining micro-indentation and meso/micro-scale simulations was proposed. In this approach, micro-indentation testing was conducted on both the coating and the substrate. A meso-scale uniaxial compression finite element model was developed to obtain a material model of the coating. This material model was incorporated within an axisymmetric micro-scale model of the coating to simulate the indentation. The proposed approach was applied to a Ti/SiC metal matrix nanocomposite (MMNC) coating, with a 5% weight of SiC nanoparticles deposited over a Ti-6Al-4V substrate using selective laser melting (SLM). Micro-indentation testing was conducted on both the Ti/SiC MMNC coating and the Ti-6Al-4V substrate. The results of the meso-scale finite element indicated that the MMNC coating can be represented using a bi-linear elastic-plastic material model, which was incorporated within an axisymmetric micro-scale model. Comparison of the experimental and micro-scale model results indicated that the proposed approach was effective in capturing the post-indentation behavior of the Ti/SiC MMNC coating. This methodology can also be used for studying the response of composite coatings with different percentages of reinforcements.
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Field, J. S., and M. V. Swain. "Determining the mechanical properties of small volumes of material from submicrometer spherical indentations." Journal of Materials Research 10, no. 1 (1995): 101–12. http://dx.doi.org/10.1557/jmr.1995.0101.
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The stress/strain behavior of bulk material is usually investigated in uniaxial tension or compression; however, these methods are not generally available for very small volumes of material. Submicrometer indentation using a spherical indenter has the potential for filling this gap with, possibly, access to hardness and elastic modulus profiles, representative stress/strain curves, and the strain hardening index. The proposed techniques are based on principles well established in hardness testing using spherical indenters, but not previously applied to depth-sensing instruments capable of measurements on a submicrometer scale. These approaches are now adapted to the analysis of data obtained by stepwise indentation with partial unloading, a technique that facilitates separation of the elastic and plastic components of indentation at each step and is able to take account of the usually ignored phenomena of “piling up” and “sinking in”.
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PASKA, ZBYNEK, JAROSLAV ROJICEK, MARTIN FUSEK, FRANTISEK FOJTIK, DAGMAR LICKOVA, and JAKUB CIENCIALA. "MOUNTING FOAMS: MAKING OF SPECIMENS AND MECHANICAL TESTING." MM Science Journal 2022, no. 3 (2022): 5893–900. http://dx.doi.org/10.17973/mmsj.2022_10_2022118.
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The article deals with the design of the technology of production of polyurethane foam (PU) specimens and with their mechanical testing. A simple procedure is proposed to produce specimens with complex shapes. The procedure is tested on two different mounting foams. These specimens were subjected to several experiments. The article presents experimental results for only one mounting foam. The tests were performed on a Testometric M500-50CT testing machine. Specifically, these are a tensile/compression test, a 3-point bending test, a shear test, and a modified indentation test. For each specimen, the displacement was also measured in the selected area with Digital Image Correlation Method. These measured data are presented in the article.
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Juliano, Thomas F., Aaron M. Forster, Peter L. Drzal, Tusit Weerasooriya, Paul Moy, and Mark R. VanLandingham. "Multiscale mechanical characterization of biomimetic physically associating gels." Journal of Materials Research 21, no. 8 (2006): 2084–92. http://dx.doi.org/10.1557/jmr.2006.0254.
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The mechanical response of living tissue is important to understanding the injury-risk associated with impact events. Often, ballistic gelatin or synthetic materials are developed to serve as tissue surrogates in mechanical testing. Unfortunately, current materials are not optimal and present several experimental challenges. Bulk measurement techniques, such as compression and shear testing geometries, do not fully represent the stress states and rate of loading experienced in an actual impact event. Indentation testing induces deviatoric stress states as well as strain rates not typically available to bulk measurement equipment. In this work, a ballistic gelatin and two styrene-isoprene triblock copolymer gels are tested and compared using both macroscale and microscale measurements. A methodology is presented to conduct instrumented indentation experiments on materials with a modulus far below 1 MPa. The synthetic triblock copolymer gels were much easier to test than the ballistic gelatin. Compared to ballistic gelatin, both copolymer gels were found to have a greater degree of thermal stability. All of the materials exhibit strain-rate dependence, although the magnitude of dependence was a function of the loading rate and testing method.
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Zhao, Jiyun, Chao Cao, Guilin Li, et al. "Study on the Similarity of Biomechanical Behavior between Gelatin and Porcine Liver." BioMed Research International 2020 (August 24, 2020): 1–10. http://dx.doi.org/10.1155/2020/7021636.
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As a natural polymer, gelatin is increasingly being used as a substitute for animals or humans for the simulation and testing of surgical procedures. In the current study, the similarity verification was neglected and a 10 wt.% or 20 wt.% gelatin sample was used directly. To compare the mechanical similarities between gelatin and biological tissues, different concentrations of gelatin samples were subjected to tensile, compression, and indentation tests and compared with porcine liver tissue. The loading rate in the three tests fully considered the surgical application conditions; notably, a loading speed up to 12 mm/s was applied in the indentation testing, the tensile test was performed at a speed of 1 mm/s until fracture, and the compression tests were compressed at a rate of 0.16 mm/s and 1 mm/s. A comparison of the results shows that the mechanical behaviors of low-concentration gelatin samples involved in the study are similar to the mechanical behavior of porcine liver tissue. The results of the gelatin material were mathematically expressed by the Mooney-Rivlin model and the Prony series. The results show that the material properties of gelatin can mimic the range of mechanical characteristics of porcine liver, and gelatin can be used as a matrix to further improve the similarity between substitute materials and biological tissues.
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Kang, Xueqin, Chi Yao, Lei Qiao, Gaofeng Ge, and Peizhong Feng. "Processing and Mechanical Properties of Ultra-high Molecular Weight Polyethylene Reinforced by Silver Nanoparticles." Polymers and Polymer Composites 25, no. 9 (2017): 683–88. http://dx.doi.org/10.1177/096739111702500906.
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The present study was designed to investigate the mechanical performance of ultra high molecular weight polyethylene (UHMWPE) reinforced by silver nanoparticles. The Ag/UHMWPE nanocomposites were prepared by a plate vulcanizing machine and tested with a contact angle micrometer, UMT friction tester, electronic universal testing machine and MicroXAM three-dimensional profilometer to characterise the wettability, ball indentation hardness, creep resistance, compression properties, and friction and wear performance. A scanning electron microscope (SEM) was employed to describe the morphology of the Ag/UHMWPE nanocomposites surfaces following the friction and wear tests. These results demonstrate that the compressive yield strength, ball indentation hardness and creep resistance increased with an increase in the content of silver nanoparticles. The contact angle of the Ag/UHMWPE nanocomposites with bovine calf serum decreases with an increase in the content of silver nanoparticles and this change increases the wettability of the Ag/UHMWPE nanocomposites. Therefore, the friction coefficient decreases, but the wear mechanism changes from scratch and furrow to fatigue flakes when the mass fraction of silver nanoparticles exceeds 0.3%. The composite with a silver nanoparticles mass fraction of 0.3% exhibits a low friction coefficient and good wear resistance.
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Li, Zong-Ming. "GENDER DIFFERENCE IN CARPAL TUNNEL COMPLIANCE." Journal of Musculoskeletal Research 09, no. 03 (2005): 153–59. http://dx.doi.org/10.1142/s0218957705001527.
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The purposes of this study were to investigate the mechanical properties of the carpal tunnel and to examine carpal tunnel compliance as it related to gender difference. Twelve male and twelve female subjects without any neuromusculoskeletal disorders in the upper extremities participated in the study. Indentation testing was manually performed on the wrist volar to the transverse carpal ligament. Effective compliance was defined as the slope of the regression analyses of indentation force and displacement data. In the tested indentation force range (2.45–19.60 N), the displacement of females was 1.38 ± 0.25 mm, significantly smaller than that of the males, 1.82 ± 0.30 mm (p < 0.001). Regression analyses in the force range showed that the effective compliance for females, 0.075 ± 0.012 mm/N, was 26.3% lower than that for males, 0.101 ± 0.018 mm/N (p < 0.005). It was concluded that females have less compliant carpal tunnel than males. The gender difference in carpal tunnel mechanics may predispose females to detrimental compression of the median nerve and carpal tunnel syndrome.
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Potrzeszcz-Sut, Beata, and Agnieszka Dudzik. "The Application of a Hybrid Method for the Identification of Elastic–Plastic Material Parameters." Materials 15, no. 12 (2022): 4139. http://dx.doi.org/10.3390/ma15124139.
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The indentation test is a popular method for the investigation of the mechanical properties of materials. The technique, which combines traditional indentation tests with mapping the shape of the imprint, provides more data describing the material parameters. In this paper, such methodology is employed for estimating the selected material parameters described by Ramberg–Osgood’s law, i.e., Young’s modulus, the yield point, and the material hardening exponent. Two combined identification methods were used: the P-A procedure, in which the material parameters are identified on the basis of the coordinates of the indentation curves, and the P-C procedure, which uses the coordinates describing the imprint profile. The inverse problem was solved by neural networks. The results of numerical indentation tests—pairs of coordinates describing the indentation curves and imprint profiles—were used as input data for the networks. In order to reduce the size of the input vector, a simple and effective method of approximating the branches of the curves was proposed. In the Results Section, we show the performance of the approximation as a data reduction mechanism on a synthetic dataset. The sparse model generated by the presented approach is also shown to efficiently reconstruct the data while minimizing error in the prediction of the mentioned material parameters. Our approach appeared to consistently provide better performance on the testing datasets with considerably easier computation than the principal component analysis compression results available in the literature.
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Cheshomi, Akbar, Golnaz Hajipour, Jafar Hassanpour, Bahman Bagha Dashtaki, Yavar Firouzei, and Ebrahim Ahmadi Sheshde. "Estimation of uniaxial compressive strength of shale using indentation testing." Journal of Petroleum Science and Engineering 151 (March 2017): 24–30. http://dx.doi.org/10.1016/j.petrol.2017.01.030.
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Gyurkó, Zoltán, and Rita Nemes. "Static Hardness Testing of Cement Mortars Containing Different Types of Recycled Construction Waste Powders." Solids 2, no. 4 (2021): 331–40. http://dx.doi.org/10.3390/solids2040021.
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The present paper deals with the hardness of cement mortars prepared with recycled materials that are potential supplementary cementitious materials (SCM). Two potential SCMs (aerated concrete powder (ACP) and concrete powder) were investigated and compared with a reference (neat cement) sample and a sample containing metakaolin (MK). The long-term performance of the mortars was studied up to the age of one year. Based on the compressive strength tests at different ages, neither concrete powder nor ACP significantly decreases the compressive strength at a 10% substitution ratio. The samples were studied with two types of static hardness tests: the Brinell hardness test and the depth sensing indentation test at two different load levels. The hardness test results indicated that the standard deviation of the results is lower at a higher load level. In the case of metakaolin and concrete powder, the change in the compressive strength was observable in the hardness test results. However, in case of the ACP, the compressive strength decreased, while the hardness increased, which can be traced back to the filler effect of aerated concrete powder. Finally, using the DSI test, the hardness results were analyzed on an energy basis. The analysis highlighted that the change in the hardness is connected to the elastic indentation energy, while it is independent from the dissipated (plastic) indentation energy.
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Naughton-Duszová, Csanádi, Sedlák, Hvizdoš, and Dusza. "Small-Scale Mechanical Testing of Cemented Carbides from the Micro- to the Nano-Level: A Review." Metals 9, no. 5 (2019): 502. http://dx.doi.org/10.3390/met9050502.
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In this overview, we summarize the results published to date concerning the small-scale mechanical testing of WC–Co cemented carbides and similar hardmetals, describing the clear trend in the research towards ever-smaller scales (currently at the nano-level). The load-size effect during micro/nanohardness testing of hardmetals and their constituents and the influence of the WC grain orientation on their deformation, hardness, indentation modulus, fracture toughness, and fatigue characteristics are discussed. The effect of the WC grain size/orientation, cobalt content, and testing environment on damage accumulation, wear mechanisms, and wear parameters are summarized. The deformation and fracture characteristics and mechanical properties, such as the yield and compression strength, of WC–Co composites and their individual WC grains at different orientations during micropillar compression tests are described. The mechanical and fracture properties of micro-cantilevers milled from WC–Co hardmetals, single WC grains, and cantilevers containing WC/WC boundaries with differently-oriented WC grains are discussed. The physical background of the deformation and damage mechanisms in cemented carbides at the micro/nano-levels is descri and potential directions for future research in this field are outlined.
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Jayababu, A., V. Arumugam, B. Rajesh, and C. Suresh Kumar. "Damage Characterization in Glass/Epoxy Composite Laminates under Normal and Oblique Planes of Cyclic Indentation Loading with AE Monitoring." Materials Evaluation 79, no. 1 (2021): 61–77. http://dx.doi.org/10.32548/2021.me-04126.
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This work focuses on the experimental investigation of indentation damage resistance in different stacking sequences of glass/epoxy composite laminates under cyclic loading on normal (0°) and oblique (20°) planes. The stacking sequence, such as unidirectional [0]12, angle ply [±45]6S, and cross ply [0/90]6S, were subjected to cyclic indentation loading and monitoring by acoustic emission testing (AE). The laminates were loaded at the center using a hemispherical steel indenter with a 12.7 mm diameter. The cyclic indentation loading was performed at displacements from 0.5 to 3 mm with an increment of 0.5 mm in each cycle. Subsequently, the residual compressive strength of the post-indented laminates was estimated by testing them under in-plane loading, once again with AE monitoring. Mechanical responses such as peak load, absorbed energy, stiffness, residual dent, and damage area were used for the quantification of the indentation-induced damage. The normalized AE cumulative counts, AE energy, and Felicity ratio were used for monitoring the damage initiation and propagation. Moreover, the discrete wavelet analysis of acoustic emission signals and fast Fourier transform enabled the calculation of the peak frequency content of each damage mechanism. The results showed that the cross-ply laminates had superior indentation damage resistance over angle ply and unidirectional (UD) laminates under normal and oblique planes of cyclic loading. However, the conclusion from the results was that UD laminates showed a better reduction in residual compressive strength than the other laminate configurations.
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Jayababu, A., V. Arumugam, B. Rajesh, and C. Suresh Kumar. "Damage Characterization in Glass/Epoxy Composite Laminates under Normal and Oblique Planes of Cyclic Indentation Loading with AE Monitoring." Materials Evaluation 79, no. 1 (2021): 61–77. http://dx.doi.org/10.32548/2020.me-04126.
Pełny tekst źródłaStreszczenie:
This work focuses on the experimental investigation of indentation damage resistance in different stacking sequences of glass/epoxy composite laminates under cyclic loading on normal (0°) and oblique (20°) planes. The stacking sequence, such as unidirectional [0]12, angle ply [±45]6S, and cross ply [0/90]6S, were subjected to cyclic indentation loading and monitoring by acoustic emission testing (AE). The laminates were loaded at the center using a hemispherical steel indenter with a 12.7 mm diameter. The cyclic indentation loading was performed at displacements from 0.5 to 3 mm with an increment of 0.5 mm in each cycle. Subsequently, the residual compressive strength of the post-indented laminates was estimated by testing them under in-plane loading, once again with AE monitoring. Mechanical responses such as peak load, absorbed energy, stiffness, residual dent, and damage area were used for the quantification of the indentation-induced damage. The normalized AE cumulative counts, AE energy, and Felicity ratio were used for monitoring the damage initiation and propagation. Moreover, the discrete wavelet analysis of acoustic emission signals and fast Fourier transform enabled the calculation of the peak frequency content of each damage mechanism. The results showed that the cross-ply laminates had superior indentation damage resistance over angle ply and unidirectional (UD) laminates under normal and oblique planes of cyclic loading. However, the conclusion from the results was that UD laminates showed a better reduction in residual compressive strength than the other laminate configurations.
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Xu, B. X., and Z. F. Yue. "Study of ratcheting by the indentation fatigue method with a flat cylindrical indenter. Part II. Finite element simulation." Journal of Materials Research 22, no. 1 (2007): 186–92. http://dx.doi.org/10.1557/jmr.2007.0019.
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The finite element method (FEM) was used to study the flat cylindrical indentation fatigue behavior using a kinematic hardening model (A-F model). This study was motivated by the experimental work of the preceding paper [B.X. Xu and Z.F. Yue, J. Mater. Res.21, 1793 (2006)], in which there were obvious similarities in the behavior of conventional fatigue specimens and indentation fatigue specimens. It is proposed that the A-F model can predict the indentation fatigue behavior. Generally, the experimental behavior of the indentation fatigue testing can be explained by the FEM analysis. In addition, the effect of residual stress on the indentation depth per cycle was studied. The effect of friction between the indenter and the specimen and evolution of von Mises stress beneath the indenter was also investigated. Numerical results showed that the effect of friction on the indentation depth propagation can be neglected. Further analysis showed that the steady-state indentation depth per cycle increases with increasing compressive residual stress and decreasing tensile residual stress.
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Wang, Yanli, Pengfei Dong, Jingyao Ke, et al. "Experimental evaluation of self-expandable metallic tracheobronchial stents." Nanotechnology Reviews 8, no. 1 (2019): 136–42. http://dx.doi.org/10.1515/ntrev-2019-0013.
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Abstract The self-expandable metallic stents have been widely used in tracheobronchial obstruction or fistulation, including the J-shaped and Y-shaped stents, named after the shape of the branch-stem junction of the stent. However, there is scarce data on the mechanical performance of these tracheobronchial stents, which is essential for optimal stent implantation. In this work, eight self-expandable metallic tracheobronchial stents in three types (i.e., straight, J-shaped, and Y-shaped), with or without cover, were characterized. The compression resistance of the stems was investigated through both compression and indentation tests. The bending resistance of the branches in the J-shaped and Y-shaped stents was assessed through the bending test. Our results demonstrated that the covered stents exhibited a significantly higher compression resistance and bending resistance than the uncovered ones. The branches had a minimal impact on the compression resistance of the stem. The branch of the J-shaped stent showed a significantly lower bending resistance than the Y shaped one. This work provides a testing framework for the J-shaped and Y-shaped stents,which could shed some light on the optimal design of stent with branches.
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Jayababu, A., V. Arumugam, B. Rajesh, and C. Suresh Kumar. "Investigation of indentation damage resistance on normal and inclined plane of glass/epoxy composite laminates using acoustic emission monitoring." Journal of Composite Materials 54, no. 21 (2020): 2953–64. http://dx.doi.org/10.1177/0021998320906864.
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This work relates to the investigation of indentation induced damage resistance in glass fiber reinforced polymer composite laminates under normal and inclined planes. Uni-directional [0] and cross-ply [0/90] glass fiber reinforced polymer composite specimens were subjected to 0° and 20° indentation loading with acoustic emission monitoring. The specimens were loaded at the centre using a hemispherical steel indenter with 12.7 mm diameter. Mechanical responses such as force–displacement behavior, absorbed energy and resulting damage area were used for the quantification of the indentation damage. Acoustic responses such as normalized cumulative counts, energy, duration and peak frequency were considered for monitoring damage progression during 0° and 20° indentation loading. The residual compressive strength of the glass fiber reinforced polymer specimens following indentation was measured by testing them under in-plane loading, once again with acoustic emission monitoring. The correlation between mechanical and acoustic strain energy was used for the evaluation of the damage severity of the laminates. The result revealed indentation damage resistance in cross-ply laminates as 65.08% and 68.01% higher than uni-directional laminates for 0°, whereas for 20°, there was a reduction in the damage resistance in cross-ply laminates to 43.27% and 57.39%. These were higher than uni-directional laminates under the displacements of 2 mm and 3 mm, respectively. The conclusion from these results was that transverse shear load at 20° inclination of laminate leads to reduction in residual compressive strength. Moreover, uni-directional glass/epoxy laminates have better residual compressive strength than cross-ply laminates for both 2 mm and 3 mm indentation displacements.
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Fang, Xufei, Lukas Porz, Kuan Ding, and Atsutomo Nakamura. "Bridging the Gap between Bulk Compression and Indentation Test on Room-Temperature Plasticity in Oxides: Case Study on SrTiO3." Crystals 10, no. 10 (2020): 933. http://dx.doi.org/10.3390/cryst10100933.
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Dislocation-based functionalities in inorganic ceramics and semiconductors are drawing increasing attention, contrasting the conventional belief that the majority of ceramic materials are brittle at room temperature. Understanding the dislocation behavior in ceramics and advanced semiconducting materials is therefore critical for the mechanical reliability of such materials and devices designed for harvesting the dislocation-based functionalities. Here we compare the mechanical testing between indentation at nano-/microscale and bulk uniaxial deformation at macroscale and highlight the dislocation plasticity in single crystal SrTiO3, a model perovskite. The similarities and differences as well as the advantages and limitations of both testing protocols are discussed based on the experimental outcome of the crystal plasticity, with a focus on the pre-existing defect population being probed with different volumes across the length scales (“size effect”). We expect this work to pave the road for studying dislocation-based plasticity in various advanced functional ceramics and semiconductors.
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LaFontaine, W. R., B. Yost, and Che-Yu Li. "Effect of residual stress and adhesion on the hardness of copper films deposited on silicon." Journal of Materials Research 5, no. 4 (1990): 776–83. http://dx.doi.org/10.1557/jmr.1990.0776.
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Continuous indentation testing was used to measure the hardness as a function of indentation depth, of three micron thick copper films deposited on silicon with an intermediate layer of 20 nm thick chromium or titanium. Three different indenters, a nearly perfect Vickers, a Vickers with a 1.2 μm2 flat, and a Pyramid with a 25 μm2 flat were employed. The hardness data suggest that the titanium interlayer produced significantly greater film/substrate adhesion than the chromium interlayer. A compressive residual stress, which relaxed with time, was detected in the samples with the titanium interlayer.
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Ding, Yao Yao, Tadafumi Adschiri, Garry A. Williams, et al. "Validation of BioDent TDI as a New Clinical Diagnostic Method." Advanced Materials Research 275 (July 2011): 151–54. http://dx.doi.org/10.4028/www.scientific.net/amr.275.151.
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Indentation is a mature technique that has been widely used in materials science to investigate the mechanical properties of metals and thin films. The indentation technique provides accurate modulus and hardness values of materials over many length scales and can target specific microstructures within heterogeneous materials. A more traditional engineering approach for mechanical properties is three point bend testing which provides an indication of the general fracture performance of the material. The breaking force and toughness results determined are based on the materials overall structure and composition. However, for both techniques, the testing specimen requires certain degree of process. This study evaluated a new indentation technique, which is able to penetrate biological tissues, apply compressive loads on the bone surface and record the resulting displacement, using wild type rats fed with a standard diet. In this study, both femurs from the same animal were tested followed by the three point bending to reach structural failure. We found a correlation between the two techniques and the properties of the bone in the animal model.
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Larsson, Per-Lennart. "On the Behavior of Mechanical Stress Fields at Indentation of Materials with Residual Stresses." Journal of Materials Engineering and Performance 30, no. 4 (2021): 2566–73. http://dx.doi.org/10.1007/s11665-021-05596-5.
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AbstractIt is an obvious fact that residual stresses can have a detrimental effect on the mechanical integrity of structures. Measuring such stresses can often be a tedious task and for that reason sharp indentation testing has been proposed as an alternative for this purpose. Correlation between global indentation properties and residual stresses has been studied quite frequently, and a solid foundation has been laid down concerning this issue. Empirical, or semi-empirical, relations have been proposed yielding results of quite good accuracy. Further progress and mechanical understanding regarding this matter will require a more in-depth understanding of the field variables at this particular indentation problem and this is the subject of the present study. In doing so, finite element simulations are performed of sharp indentation of materials with and without residual stresses. Classical Mises plasticity and conical indentation are considered. The main conclusion from this study is that the development of stresses in materials with high or medium-sized compressive residual stresses differs substantially from a situation with tensile residual stresses, both as regards the level of elastic deformation in the contact region and the sensitivity of such stresses. Any attempt to include such stress states in a general correlation effort of indentation quantities is therefore highly unlikely to be successful.
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Nuriev, A. A., and Sh Kh Sultanov. "Using proppant indentation coefficient in design of hydraulic fracturing treatment of oil source rocks." Earth sciences and subsoil use 45, no. 3 (2022): 305–12. http://dx.doi.org/10.21285/2686-9993-2022-45-3-305-312.
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The purpose of the study is the laboratory determination of proppant indentation coefficients depending on the geological composition of the oil source rocks and their application in the design of hydraulic fracturing treatment. The laboratory researches used the core material of oil-producing deposits of the Domanic formation. The indentation of prop pant was carried out on the CTM-100 compression testing machine, in order to eliminate the measurement error, the size of the cells was additionally specified using ADF U300P microscope with the operation capacity either in reflected light or reflected and transmitted light only. As a result, the geological features of the Domanic complex were confirmed: a large content of organic matter was traced on the core material, the bulk of the rock was composed of carbonates with frequent lithological layering. The indentation coefficient of 20/40 proppan were as following: 0.2–0.4 mm in limestones, 0.23–0.45 mm in clay limestones, 0.47 mm for organic matter. The indentation coefficients for 30/50 proppant were as follows: 0.1– 0.5 mm in limestones, 0.13–0.55 mm in clay limestones, 0.47 mm in organic matter. The use of the obtained coefficients in the design of hydraulic fracturing treatment allowed to specify the fixed width of the crack opening that will have a positive effect on the predicted starting well yield under subsequent modeling. The proppant indentation is in direct relationship to the composition of the oil-producing rocks. When using the proppant coefficients it is advisable to pay additional attention to the proppant tracking map. The use of laboratory studies with subsequent modeling in the hydraulic fracturing simulator allows more accurate understanding of the fixed geometry of the crack of the formation fracturing. Estimation of the crack opening width at the stage of hydraulic fracturing design makes it possible to adapt the parameters of formation treatment, which has a positive effect on the lifetime of the crack width as well as on the well yield.
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Zaharia, Sebastian Marian, Mihai Alin Pop, Lucia-Antoneta Chicos, et al. "Compression and Bending Properties of Short Carbon Fiber Reinforced Polymers Sandwich Structures Produced via Fused Filament Fabrication Process." Polymers 14, no. 14 (2022): 2923. http://dx.doi.org/10.3390/polym14142923.
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Additive manufacturing, through the process of thermoplastic extrusion of filament, allows the manufacture of complex composite sandwich structures in a short time with low costs. This paper presents the design and fabrication by Fused Filament Fabrication (FFF) of composite sandwich structures with short fibers, having three core types C, Z, and H, followed by mechanical performance testing of the structures for compression and bending in three points. Flatwise compression tests and three-point bending have clearly indicated the superior performance of H-core sandwich structures due to dense core structures. The main modes of failure of composite sandwich structures were analyzed microscopically, highlighting core shear buckling in compression tests and face indentation in three-point bending tests. The strength–mass ratio allowed the identification of the structures with the best performances considering the desire to reduce the mass, so: the H-core sandwich structures showed the best results in compression tests and the C-core sandwich structures in three-point bending tests. The feasibility of the FFF process and the three-point bending test of composite wing sections, which will be used on an unmanned aircraft, have also been demonstrated. The finite element analysis showed the distribution of equivalent stresses and reaction forces for the composite wing sections tested for bending, proving to validate the experimental results.
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Wu, Yuchin, Samer M. Adeeb, M. John Duke, David Munoz-Paniagua, and Michael R. Doschak. "Compositional and Material Properties of Rat Bone after Bisphosphonate and/or Strontium Ranelate Drug Treatment." Journal of Pharmacy & Pharmaceutical Sciences 16, no. 1 (2013): 52. http://dx.doi.org/10.18433/j3c59h.
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Purpose. We investigated elemental strontium and/or bisphosphonate drug incorporation upon the compositional and biomechanical properties of vertebral bone, in a rat model of Osteoporosis secondary to ovariectomy. Methods. Six month old female rats were ovariectomized (OVX) and divided into untreated OVX-Vehicle, OVX-RIS (Risedronate bisphosphonate [BP] treated), OVX-SrR (Strontium Ranelate [Protos®] treated), combination OVX-RIS+SrR, and sham-operated controls. After 16 weeks of treatment, rats were euthanized and lumbar vertebra were dissected. Micro-Computed Tomography (micro-CT), Electron Probe Micro-Analysis (EPMA), mechanical testing in compression and nano-indentation testing were then undertaken to evaluate bone morphometry, elemental composition, material properties and strength. Results. Bone Volume was significantly reduced in the OVX-Vehicle (133±10mm3) compared with OVX-RIS (169±22mm3), OVX-SrR (145±2mm3), and OVX-RIS+SrR (172±8mm3). EPMA mapped elemental Sr deposition to the periosteal surface of cortical bone (50-100 µm thick), endosteal trabecular surfaces (20 µm thick), as well as to both vertebral growth plates. The atomic ratios of (Ca+Sr)/P were significantly reduced with SrR treatment (2.4%-6.6%), indicating Sr incorporation into bone mineral. No significant differences were measured in vertebral bone reduced modulus by nano-indentation. Conversely, all BP-dosed groups had significantly increased structural bone strength. Conclusions. Thus, we conclude that BP drugs dominate the conservation of trabecular geometry and structural strength in OP rats, whereas Sr drugs likely influence bone volume and material composition locally. 
 
 This article is open to POST-PUBLICATION REVIEW. Registered readers (see “For Readers”) may comment by clicking on ABSTRACT on the issue’s contents page.
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Rahman, Asif, Tadafumi Adschiri, and Mohammed Farid. "Microindentation of Microencapsulated Phase Change Materials." Advanced Materials Research 275 (July 2011): 85–88. http://dx.doi.org/10.4028/www.scientific.net/amr.275.85.
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Due to the small size of microcapsules (1-1000 µm) used in a large number of applications, the individual rupture force of an individual particle has been difficult to obtain. A new technique involving nanomechanical testing was used in this study. We propose a standard method of testing the individual rupture force of Micronal®DS5008 microcapsules with an average size of approximately 11.2µm. Microcapsules were subjected to compressive force testing to determine the amount of force required to rupture the microcapsules. In order to find the mechanical properties of these microcapsules a standard nanoindentation system was setup with a 10µm radius diamond head cone indentation tip and the individual microcapsules were compressed till rupture occurred.
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Wähnert, Dirk, Konrad L. Hoffmeier, Yves Stolarczyk, Rosemarie Fröber, Gunther O. Hofmann, and Thomas Mückley. "Evaluation of a Customized Artificial Osteoporotic Bone Model of the Distal Femur." Journal of Biomaterials Applications 26, no. 4 (2010): 451–64. http://dx.doi.org/10.1177/0885328210367830.
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In the development of new implants biomechanical testing is essential. Since human bones vary markedly in density and geometry their suitability for biomechanical testing is limited. In contrast artificial bones are of great uniformity and therefore appropriate for biomechanical testing. However, the applied artificial bones have to be proved as comparable to human bone. An anatomical shaped artificial bone representing the distal human femur was created by foaming polyurethane. To get a bone model with properties of osteoporotic bone a foam density of 150 kg/m3 was used. The biomechanical properties of our artificial bones were evaluated against eight mildly osteoporotic fresh frozen human femora by mechanical testing. At the artificial bones all tested parameters showed a very small variation. In contrast significant correlation between bone mass density and tested parameters was found for the human bones. The artificial bones reached 39% of the compression strength and 41% of the screw pullout force of the human bone. In indentation testing the artificial bones reached 27% (cancellous) and 59% (cortical) respectively of the human bones strength. Regarding Shore hardness artificial bone and human bone showed comparable results for the cortical layer and at the cancellous layer the artificial bone reached 57% of human bones hardness. Our described method for customizing of artificial bones regarding their shape and bone stock quality provides suitable results. In relation to the as mildly osteoporotic classified human bones we assume that the biomechanical properties matching to serve osteoporotic bone.
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Spitsen, R., D. Kim, B. Flinn, M. Ramulu, and E. T. Easterbrook. "The Effects of Post-Weld Cold Working Processes on the Fatigue Strength of Low Carbon Steel Resistance Spot Welds." Journal of Manufacturing Science and Engineering 127, no. 4 (2005): 718–23. http://dx.doi.org/10.1115/1.2034514.
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The investigation on the use of a post-weld cold working process to improve fatigue strength of low carbon steel resistance spot welds is presented. The cold working process generates uniform and consistent large zones of compressive residual stresses in resistance spot-welded low carbon steel structures using a specially designed indentation device. The effect of the indentation process parameters on the mechanical properties of the resistance spot weld was investigated. Comparisons of the mechanical properties and qualitative results between the as-resistance spot-welded specimens and the post-weld cold worked resistance spot-welded specimens have been made in this investigation. Fatigue testing was also conducted to evaluate the effect of post-weld cold working process on the fatigue characteristics of resistance spot welds. Results showed that a significant improvement in the fatigue strength has been achieved through the post-weld cold working process.
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Ingole, Vijay H., Shubham S. Ghule, Tomaž Vuherer, Vanja Kokol, and Anil V. Ghule. "Mechanical Properties of Differently Nanostructured and High-Pressure Compressed Hydroxyapatite-Based Materials for Bone Tissue Regeneration." Minerals 11, no. 12 (2021): 1390. http://dx.doi.org/10.3390/min11121390.
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Hydroxyapatite (HAp) has long been considered the gold standard in the biomedical field, considering its composition and close resemblance to human bone. However, the brittle nature of hydroxyapatite (HAp) biomaterial, constrained by its low fracture toughness (of up to 1.2 vs. 2–12 MPa m1/2 of human bone), remains one of the significant factors impairing its use in bone regeneration. In the present study, HAp nanoparticles synthesized by the solid-state (SHAp) and sonochemical (EHAp) approaches using eggshell-derived calcium hydroxide and ammonium dihydrogen orthophosphate as precursors are compared with those synthesized using commercially available calcium hydroxide and ammonium dihydrogen orthophosphate as precursors (CHAp) employing sonochemical method. The HAp samples were then compressed into compact materials using a uniaxial high-pressure compression technique at a preoptimized load and subsequently characterized for mechanical properties using the Vickers indentation method and compressive strength testing. The analysis revealed that the material with smaller particle size (30–40 nm) and crystalline nature (EHAp and CHAp) resulted in mechanically robust materials (σm = 54.53 MPa and 47.72 MPa) with high elastic modulus (E = 4011.1 MPa and 2750.25 MPa) and density/hardness-dependent fracture toughness (σf = 4.34 MPa m1/2and 6.57 MPa m1/2) than SHAp (σm =28.40 MPa, E = 2116.75 MPa, σf = 5.39 MPa m1/2). The CHAp material was found to be the most suitable for applications in bone regeneration.
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Photiou, Demetris, Stelios Avraam, Francesco Sillani, Fabrizio Verga, Olivier Jay, and Loucas Papadakis. "Experimental and Numerical Analysis of 3D Printed Polymer Tetra-Petal Auxetic Structures under Compression." Applied Sciences 11, no. 21 (2021): 10362. http://dx.doi.org/10.3390/app112110362.
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Auxetic structures possess a negative Poisson ratio (ν < 0) as a result of their geometrical configuration, which exhibits enhanced indentation resistance, fracture toughness, and impact resistance, as well as exceptional mechanical response advantages for applications in defense, biomedical, automotive, aerospace, sports, consumer goods, and personal protective equipment sectors. With the advent of additive manufacturing, it has become possible to produce complex shapes with auxetic properties, which could not have been possible with traditional manufacturing. Three-dimensional printing enables easy and precise control of the geometry and material composition of the creation of desirable shapes, providing the opportunity to explore different geometric aspects of auxetic structures with a variety of different materials. This study investigated the geometrical and material combinations that can be jointly tailored to optimize the auxetic effects of 2D and 3D complex structures by integrating design, modelling approaches, 3D printing, and mechanical testing. The simulation-driven design methodology allowed for the identification and creation of optimum auxetic prototype samples manufactured by 3D printing with different polymer materials. Compression tests were performed to characterize the auxetic behavior of the different system configurations. The experimental investigation demonstrated a Poisson’s ration reaching a value of ν = −0.6 for certain shape and material combinations, thus providing support for preliminary finite element studies on unit cells. Finally, based on the experimental tests, 3D finite element models with elastic material formulations were generated to replicate the mechanical performance of the auxetic structures by means of simulations. The findings showed a coherent deformation behavior with experimental measurements and image analysis.
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Song, Xue-Jun, San-Jue Hu, Kenneth W. Greenquist, Jun-Ming Zhang, and Robert H. LaMotte. "Mechanical and Thermal Hyperalgesia and Ectopic Neuronal Discharge After Chronic Compression of Dorsal Root Ganglia." Journal of Neurophysiology 82, no. 6 (1999): 3347–58. http://dx.doi.org/10.1152/jn.1999.82.6.3347.
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Chronic compression of the dorsal root ganglion (CCD) was produced in adult rats by implanting a stainless steel rod unilaterally into the intervertebral foramen, one rod at L4 and another at L5. Two additional groups of rats received either a sham surgery or an acute injury consisting of a transient compression of the ganglion. Withdrawal of the hindpaw was used as evidence of a nocifensive response to mechanical and thermal stimulation of the plantar surface. In addition, extracellular electrophysiological recordings of spontaneous discharges were obtained from dorsal root fibers of formerly compressed ganglia using an in vitro nerve-DRG-dorsal root preparation. The mean threshold force of punctate indentation and the mean threshold temperature of heating required to elicit a 50% incidence of foot withdrawal ipsilateral to the CCD were significantly lower than preoperative values throughout the 35 days of postoperative testing. The number of foot withdrawals ipsilateral to the CCD during a 20-min contact with a temperature-controlled floor was significantly increased over preoperative values throughout postoperative testing when the floor was 4°C (hyperalgesia) and, to a lesser extent, when it was 30°C (spontaneous pain). Stroking the foot with a cotton wisp never elicited a reflex withdrawal before surgery but did so in most rats tested ipsilateral to the CCD during the first 2 postoperative weeks. In contrast, the CCD produced no changes in responses to mechanical or thermal stimuli on the contralateral foot. The sham operation and acute injury produced no change in behavior other than slight, mechanical hyperalgesia for ∼1 day, ipsilateral to the acute injury. Ectopic spontaneous discharges generated within the chronically compressed ganglion and, occurring in the absence of blood-borne chemicals and without an intact sympathetic nervous system, were recorded from neurons with intact, conducting, myelinated or unmyelinated peripheral nerve fibers. The incidence of spontaneously active myelinated fibers was 8.61% for CCD rats versus 0.96% for previously nonsurgical rats. We hypothesize that a chronic compression of the dorsal root ganglion after certain injuries or diseases of the spine may produce, in neurons with intact axons, abnormal ectopic discharges that originate from the ganglion and potentially contribute to low back pain, sciatica, hyperalgesia, and tactile allodynia.
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Enriquez, Mike Louie C., Ronnie S. Concepcion II, R.-Jay S. Relano, et al. "optIFnet: A Capacitive Antenna Dipole Indention-Flexure Predictive Model Optimized Using Hybrid Lichtenberg Algorithm and Neural Network." Journal of Advanced Computational Intelligence and Intelligent Informatics 27, no. 1 (2023): 27–34. http://dx.doi.org/10.20965/jaciii.2023.p0027.
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In performing underground imaging surveying, applying a coating in the antenna dipole plates with robust and durable material to stay protected against rough road features is vital to consider. By doing this, the mechanical properties of the metallic antenna dipole can be improved and be shielded from deterioration. With that, this study has developed an indentation-flexure algorithm optimized using a hybrid Lichtenberg algorithm (LA) and artificial neural network (ANN) that can predict the indentation-flexure as a function of the coating material’s elastic modulus, Poisson ratio, and thickness as well as the load antenna weight. Acrylic, epoxy, nylon 101, high-density polyethylene, and polyvinyl chloride were chosen as the top five most popular coating materials. A 120° titanium cone indenter with a 0.5-inch-diameter, slightly rounded point, and a constant compressive force of 200 N in the center was employed to plot and use a nonlinear mechanical finite element analysis on an antenna dipole plate using SolidWorks. Nature-inspired and evolutionary metaheuristics such as African vultures, Lichtenberg, and gorilla troop optimization algorithm including genetic algorithm (GA) were employed as optimized models for the hardness indentation for capacitively coupled antenna dipoles. Based on the results, the hybrid LA-ANN solution with a hidden neurons of 3000 and a sigmoid activation function is the best performing model as it acquired a MSE score of 0.0061 in validation and 0.1478 in testing compare to the other model with 0.1610 for GA with 100 hidden neurons with sigmoid activation function. Thus, LA-ANN model is considered as the optIFnet as it exhibited the best prediction performance and fastest convergence among all optimizers used.
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Kovács, Zs, N. Q. Chinh, and J. Lendvai. "Orientation dependence of Portevin–Le Châtelier plastic instabilities in depth-sensing microindentation." Journal of Materials Research 16, no. 4 (2001): 1171–77. http://dx.doi.org/10.1557/jmr.2001.0161.
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Plastic instabilities were investigated in an Al–Zn–Mg–Cu alloy by depth-sensing microhardness testing in Vickers geometry. The alloy investigated showed strong age hardening as a consequence of Guiner–Preston zone formation at room temperature. The orientation dependence of the Portevin–Le Chátelier (PLC) effect was investigated by microindentation tests in differently oriented grains. If the direction of the indentation was close to the 〈100〉 crystal axis and the diagonal of the Vickers indenter coincides with the 〈110〉 crystal direction, the PLC effect was more pronounced. Under these conditions the instabilities could be observed even after 5 h of natural aging, while the PLC effect disappeared in grains with other orientations after 2 h of aging. The orientation dependence of the indentation curves was observed up to the maximal measured imprint size (d ≈ 80 μm). It is suggested that the initialization of the PLC bands takes place in the close vicinity of indenter/sample contact surface. Considering only a uniaxial compressive stress component in the sample/indenter contact planes, in the vicinity of the indenter single sliplike and multiple sliplike conditions are attained depending on the orientation of the indenter relative to the sample. Changes of the slip conditions correlate with changes in the observation regime of instability which explains the orientation dependence.
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Liu, Yang, Wen Jun Xi, and Shu Jie Li. "Effect of Ti Content on the Microstructure and Properties of TiC/TiB2-FeNiCr Composite Prepared by Thermite Reaction." Materials Science Forum 789 (April 2014): 403–8. http://dx.doi.org/10.4028/www.scientific.net/msf.789.403.
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TiC/TiB2-FeNiCr composite reinforced by TiC and TiB2 composite ceramic particles was successfully in-situ synthesized using thermite reaction. The effects of Ti content in the raw material on the microstructure and properties of the composite were studied. The microstructure was investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM) and electron probe microanalysis (EPMA). The hardness, compressive strength and wear resistance were tested using the Vickers indentation method (HXZ-1000), mechanical testing machine (SANS5105) and the high temperature wear tester (HT-600), respectively. The results show that the composite is mainly consisted of TiC, TiB2, Cr7C3, α-FeNiCr and NiAl. The content of TiC and TiB2 is increased with the Ti content. The hardness and compressive strength of the composite is increased first and then decreased. They attain the maximum value at about 8.0wt%Ti. The hardness and the compressive strength of the composite are 1313.25HV and 2725.57MPa at 8.0% Ti. Also the wear resistance of the composite is good, and the weight wear loss at 8.0% Ti is nearly fifth of the mass loss of steel.
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Aziz, Naj, Ali Mirzaghorbanali, Jan Nemcik, Kay Heemann, and Stefan Mayer. "Shear strength properties of plain and spirally profiled cable bolts." Canadian Geotechnical Journal 52, no. 10 (2015): 1490–95. http://dx.doi.org/10.1139/cgj-2014-0504.
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An experimental investigation into the performance of two 22 mm diameter, 60 t tensile strength capacity Hilti cable bolts in shear was conducted using the double-shear testing apparatus at the laboratory of the School of Civil, Mining and Environmental Engineering, Faculty of Engineering and Information Sciences, University of Wollongong. The tested cable bolts were (i) Hilti 19 wire HTT-UXG plain strand and (ii) Hilti 19 wire HTT-IXG spirally profiled (smaller cross-sectional area than the plain one) cable bolt, with indentation only on the surface of the outer strands. These cable bolts are of sealed wire construction type, consisting of an outer 5.5 mm diameter wire layer overlying the middle 3 mm diameter wire strands. Both layers are wrapped around a single solid 7 mm diameter strand wire core. The double-shearing test was carried out in 40 MPa concrete blocks, contained in concrete moulds. Cable bolts were encapsulated in concrete using Orica FB400 pumpable grout. Prior to encapsulation, each cable bolt was pre-tensioned initially to 50 kN axial force. A 500 t capacity servocontrolled compression testing machine was used for both tests, and during each test the vertical shear displacement was limited to 70 mm of travel. The rate of vertical shear displacement was maintained constant at 1 mm/min. The maximum shear load achieved for the plain strand cable was 1024 kN, while the spiral cable peak load was 904 kN, before the cable bolt wires began to individually snap, leading to the cable bolt break-up into two sections. It is apparent that spiral profiles of the outer wires weaken both the tensile and shearing strength. Finally, another set of tests was undertaken using the British Standard single-shear approach, producing lower shear strength values.
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Gauthier, Maxime, Aurélien Katz, Antoine Maison, Cristian V. Cojocaru, and Fabrice Bernier. "Effect of hardening heat treatment on the mechanical properties of a 17-4PH stainless steel foam." MRS Advances 3, no. 62 (2018): 3655–68. http://dx.doi.org/10.1557/adv.2018.614.
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AbstractThis paper presents the results of a study on the impact of a precipitation hardening treatment on the mechanical properties of 17-4PH stainless steel open-cell foams produced using a powder-metallurgy-based process patented by the National Research Council Canada (NRC). Pre-alloyed powder was used to manufacture stainless steel (SS) foams with either medium or high porosity by changing the nature of the organic binder used to process the porous materials. Some of these were kept in the as-sintered state, while others were submitted to the H900 precipitation hardening treatment frequently prescribed for 17-4PH stainless steels.Metallurgical and physical characterization was carried out on the resulting materials, along with mechanical testing at the micro (indentation testing) and macro (compressive testing) scales. It was found that the Medium-Porosity Foams (MPF) and High-Porosity Foams (HPF) had very different morphologies, the HPFs having a delicate porous structure featuring thin sintered walls with many openings (a.k.a. windows) between the main cells, while the MPFs exhibited much thicker walls with few windows connecting the larger pores. As expected from these foam morphologies, the mechanical properties of MPFs were much higher than those of the more porous and delicate HPF materials. For both foam types, the average mechanical properties were improved by the H900 treatment. A comparison with compressive properties of 17-4PH foams taken from the literature resulted in reasonable agreement. However, the large scatter observed on the average compressive properties of the NRC foams and the slightly different structure/composition of the literature materials mean that any comparison between these porous alloys must be interpreted with caution.