Academic literature on the topic 'Stiffness comparable'
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Journal articles on the topic "Stiffness comparable"
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B., B. Konar. "Study of interactions between a novel elastomer and solvents." Journal of Indian Chemistry Society Vol. 78, October-December 2001 (2001): 757–59. https://doi.org/10.5281/zenodo.5898010.
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Department of Polymer Science & Technology, University of Calcutta, 92, A. P. C. Road, Kolkata-700 009, India <em>Manuscript received 31 August 2001</em> The flexibility parameters of chlorosulfonated polyethylene indicate chain stiffness comparable to other synthetic elastomers. Similar conclusion is also reached from a study of the hydrodynamic behavior. The Mark-Houwink constants, obtained from the molecular weight dependence of [<em>ŋ</em>] also indicate a fairly coiled up configuration for the molecular chain. The parameters characterizing the stiffness of the elastomer chain, such as the effective bond length (<em>b</em>), the stric factor (<em>ơ</em>) also reveal that the chlorosulfonated polyethylene chain resembles the other elastomers so far as the chain flexibility is concerned. Unperturbed dimension values obtained from <em>ϴ</em>-solvent data and other theories of dilute polymer solutions show good agreement with each other.
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Gardner, T. N., and M. Evans. "Relative stiffness, transverse displacement and dynamization in comparable external fixators." Clinical Biomechanics 7, no. 4 (1992): 231–39. http://dx.doi.org/10.1016/s0268-0033(92)90006-p.
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Schwarzenberg, P., T. Colding-Rasmussen, D. Hutchinson, et al. "LIGHT-CURABLE FRACTURE FIXATION SOLUTION COMPARABLE WITH METAL PLATES IN TORSION." Orthopaedic Proceedings 105-B, SUPP_7 (2023): 122. http://dx.doi.org/10.1302/1358-992x.2023.7.122.
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The objective of this study was to investigate how a new customizable light-curable osteosynthesis method (AdFix) compared to traditional metal hardware when loaded in torsion in an ovine phalanx model.Twenty-one ovine proximal phalanges were given a 3mm transverse osteotomy and four 1.5mm cortex screws were inserted bicortically on either side of the gap. The light-curable polymer composite was then applied using the method developed by Hutchinson [1] to create osteosyntheses in two groups, having either a narrow (6mm, N=9) or a wide (10mm, N=9) fixation patch. A final group (N=3) was fixated with conventional metal plates. The constructs were loaded in torsion at a rate of 6°/second until failure or 45° of rotation was reached. Torque and angular displacement were measured, torsional stiffness was calculated as the slope of the Torque-Displacement curve, and maximum torque was queried for each specimen.The torsional stiffnesses of the narrow, wide, and metal plate constructs were 39.1 ± 6.2, 54.4 ± 6.3, and 16.2 ± 3.0 Nmm/° respectively. All groups were statistically different from each other (p<0.001). The maximum torques of the narrow, wide, and metal plate constructs were 424 ± 72, 600 ± 120, and 579 ± 20 Nmm respectively. The narrow constructs were statistically different from the other two (p<0.05), while the wide and metal constructs were not statistically different from each other (p=0.76).This work demonstrated that the torsional performance of the novel solution is comparable to metal fixators. As a measure of the functional range, the torsional stiffness in the AdhFix exceeded that of the metal plate. Furthermore, the wide patches were able to sustain a similar maximum toque as the metal plates. These results suggest AdhFix to be a viable, customizable alternative to metal implants for fracture fixation in the hand.
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Hopkins, Justin, Nasser Heyrani, Christopher Kreulen, Tanya Garcia, Blaine Christiansen, and Eric Giza. "InternalBrace has Comparable Stiffness and Strength as Tightrope for Lisfranc Fixation." Foot & Ankle Orthopaedics 2, no. 3 (2017): 2473011417S0001. http://dx.doi.org/10.1177/2473011417s000196.
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Category: Sports, Biomechanics Introduction/Purpose: Lisfranc injuries are characterized by disruption between the medial cuneiform and base of the second metatarsal. Conventional interfragmentary screws decreases the amount of diastasis, however is believed to decrease the natural physiological movement of the joint compared to suture button (Tightrope, Arthrex, Inc., Naples, FL). The InternalBrace (IB, Arthrex, Inc., Naples, FL) allows physiologic movement and collagen ingrowth, while also decreasing iatrogenic bone loss. It also prevents erosion of the suture button into the medial cuneiform and prevents irritation of the tibialis anterior tendon. We hypothesized that there was no significant difference in the mechanical properties of these three constructs. Methods: Three groups of 10 sawbone models were used in this study. Two fourth generation 20 mm cylinder sawbones with open cell foam were fixed together with either a 3.5 mm conventional screw, mini Tightrope or IB with a curved button and 4.75 mm biotenodesis screw. Sawbone constructs were held in a mechanical testing system (Model 809, MTS Systems Corp, Minneapolis MN) using custom fixtures. Constructs were loaded in axial tension at 0.5mm/sec until failure. Load-displacement data were plotted for each test. Yield, stiffness, ultimate strength (US), yield energy, post-yield energy and ultimate strength energy were calculated Additionally, the load and energy to 0.5 mm, 1.0 mm and 1.5 mm of displacement were captured to relate strength at clinically relevant displacements. The residuals of an ANOVA on all mechanical testing results were not normally distributed. Therefore non-parametric comparison was used to compare fixation types (Proc NPAR1WAY, SAS 9.4, SAS Institute). Results: Compared to IB, the screw demonstrated greater stiffness, yield load and energy, and ultimate load and energy, with smaller yield, ultimate and failure displacement. When comparing the Tightrope and IB, there was no difference in stiffness (p=0.82), although the Tightrope performed greater in terms of having a larger yield load, energy and displacement, a larger ultimate strength load, energy and displacement, and a larger failure load, energy and displacement. When assessing the load at various distances of displacement, there was no significant difference between the load at 0.5 mm displacement (p=0.5, Figure 1). At greater displacement, the load was greater in the Tightrope than the IB (Figure 1). Conclusion: In this study, IB has shown proper stiffness and strength for fixation of ligamentous lisfranc injury. However, if a diastasis of >0.5 mm is evident, concerns for a clinical failure should be examined. This is the first study examining the use of an IB for treatment of a ligamentous lisfranc injury. The data supports its current clinical indications and further studies in cadaveric models are recommended.
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Roque, Reynaldo, William G. Buttlar, Byron E. Ruth, and Stephen W. Dickison. "Short-Loading-Time Stiffness from Creep, Resilient Modulus, and Strength Tests Using Superpave Indirect Tension Test." Transportation Research Record: Journal of the Transportation Research Board 1630, no. 1 (1998): 10–20. http://dx.doi.org/10.3141/1630-02.
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The Superpave indirect tension (IDT) system was modified to determine the short-loading-time stiffness of asphalt mixtures from resilient modulus, creep, and strength tests. The idea was not only to provide a more accurate method to determine the resilient modulus, but also to determine whether reasonable measures of short-loading-time stiffness could be obtained from tests that provide other properties and thereby minimize the amount of testing needed to characterize asphalt mixtures. It was found that even when evaluated at very short loading times, the stiffnesses determined from the different tests were significantly different. Detailed evaluation indicated that the differences can be explained by the differences in loading rates between the tests. In general, stiffnesses from the different tests all appeared to be reasonable and followed the same trend. However, since the rheological behavior of asphalts and mixtures varies, stiffnesses from different tests were not directly related. Therefore, although the interpretation methods developed in this study for creep and strength tests appear to provide a reasonable alternative to the resilient or dynamic modulus, the short-loading-time stiffnesses determined from these tests are not directly comparable with the resilient or dynamic modulus or with each other. The work illustrates the sensitivity of stiffness to relatively small changes in loading rate and other variables, which emphasizes the need to precisely define load pattern, load level, and data interpretation methods to determine asphalt mixture stiffness at short loading times.
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Lehnhoff, T. F., Kwang Il Ko, and M. L. McKay. "Member Stiffness and Contact Pressure Distribution of Bolted Joints." Journal of Mechanical Design 116, no. 2 (1994): 550–57. http://dx.doi.org/10.1115/1.2919413.
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Member stiffnesses and the stress distributions in the bolts and members of bolted joints have been calculated for various bolt sizes, as well as thicknesses and materials of the members. The finite element method has been used to calculate the displacement and the stress distributions in the components of the bolted joint. Using axisymmetric elements, the bolted joint could be analyzed as a two-dimensional problem. Member stiffness ratios were calculated from the finite element results and compared with those calculated by a commonly used theory. The values were approximately comparable (16–30 percent difference) for the assumptions under which the theory was applied. Formulas and dimensionless curves which can be used to estimate the member stiffness ratios for several kinds of bolted joints are presented.
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Deshmukh, S. N., and N. K. Chandiramani. "LQR Control of Wind Excited Benchmark Building Using Variable Stiffness Tuned Mass Damper." Shock and Vibration 2014 (2014): 1–12. http://dx.doi.org/10.1155/2014/156523.
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LQR control of wind induced motion of a benchmark building is considered. The building is fitted with a semiactive variable stiffness tuned mass damper adapted from the literature. The nominal stiffness of the device corresponds to the fundamental frequency of the building and is included in the system matrix. This results in a linear time-invariant system, for which the desired control force is computed using LQR control. The control force thus computed is then realized by varying the device stiffness around its nominal value by using a simple control law. A nonlinear static analysis is performed in order to establish the range of linearity, in terms of the device (configuration) angle, for which the control law is valid. Results are obtained for the cases of zero and nonzero structural stiffness variation. The performance criteria evaluated show that the present method provides displacement control that is comparable with that of two existing controllers. The acceleration control, while not as good as that obtained with the existing active controller, is comparable or better than that obtained with the existing semiactive controller. By using substantially less power as well as control force, the present control yields comparable displacement control and reasonable acceleration control.
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Hartman, Curtis W., Nicholas C. Branting, Matthew A. Mormino, et al. "Unicortical Locking Screws Provide Comparable Rigidity to Bicortical Compression Screws in Tranverse Mid-Shaft Clavicle Fracture Plate Fixation Constructs." Clinics and Practice 15, no. 6 (2025): 101. https://doi.org/10.3390/clinpract15060101.
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Background: Mid-shaft clavicle fracture fixation carries neurovascular injury risk. The purpose of this study was to compare bicortical compression and unicortical locked clavicle plate constructs biomechanically. Materials and Methods: Ten fourth-generation composite transverse mid-shaft clavicle osteotomy specimens were assigned to two groups, and each clavicle was fixed with an eight-hole second-generation 3.5 mm pelvic reconstruction plate placed superiorly. Group one included five fixed with bicortical compression screws and group two included five fixed with unicortical locking screws. All were tested on a four-axis servohydraulic testing frame in three modes: axial rotation, anterior/posterior bending, and cephalad/caudad bending. Results: Mean construct stiffness for AP bending was 1.255 ± 0.058 Nm/deg (group 1) and 1.442 ± 0.065 Nm/deg (group 2) (p = 0.001). Mean construct stiffness for axial rotation was 0.701 ± 0.08 Nm/deg (1) and 0.726 ± 0.03 Nm/deg (2) (p = 0.581). Mean construct stiffness for cephalad bending was 0.889 ± 0.064 Nm/deg (1) and 0.880 ± 0.044 Nm/deg (2) (p = 0.807). Mean construct stiffness for caudal bending was 2.523 ± 0.29 Nm/deg (1) and 2.774 ± 0.25 Nm/deg (2) (p = 0.182). Conclusions: With transverse mid-shaft clavicle fractures, unicortical locking fixation provided comparable rigidity to bicortical compression fixation in axial rotation, cephalad bending, and caudal bending; it provided greater rigidity in AP bending.
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O. Tang, T., and R. K.L. Su. "Shear and Flexural Stiffnesses of Reinforced Concrete Shear Walls Subjected to Cyclic Loading." Open Construction and Building Technology Journal 8, no. 1 (2014): 104–21. http://dx.doi.org/10.2174/1874836801408010104.
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Seismic analyses of concrete structures under maximum-considered earthquakes require the use of reduced stiffness accounting for cracks and degraded materials. Structural walls, different to other flexural dominated components, are sensitive to both shear and flexural stiffness degradations. Adoption of the gross shear stiffness for walls in seismic analysis prevails particularly for the design codes in the US. Yet available experimental results indicate that this could overstate the shear stiffness by more than double, which would hamper the actual predictions of building periods and shear load distributions among columns and walls. In addition, the deformation capacity could be drastically understated if the stipulated constant ductility capacity is adopted. This paper reviews the available simplified shear and flexural models, which stem from classical mechanics, empirical formulations and/or parametric studies, suitable for structural walls at the state-of-the-art. Reviews on the recommended flexural and shear stiffnesses by prominent design codes such as ACI318-11, Eurocode 8 and CSA are included. A database comprised of walls subjected to reverse-cyclic loads is formed to evaluate the performance of each model. It is found that there exist classical models that could outweigh overconservative codified values with comparable simplicity for practical uses.
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Prager, Jon, Christopher F. Adams, Alexander M. Delaney, et al. "Stiffness-matched biomaterial implants for cell delivery: clinical, intraoperative ultrasound elastography provides a ‘target’ stiffness for hydrogel synthesis in spinal cord injury." Journal of Tissue Engineering 11 (January 2020): 204173142093480. http://dx.doi.org/10.1177/2041731420934806.
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Safe hydrogel delivery requires stiffness-matching with host tissues to avoid iatrogenic damage and reduce inflammatory reactions. Hydrogel-encapsulated cell delivery is a promising combinatorial approach to spinal cord injury therapy, but a lack of in vivo clinical spinal cord injury stiffness measurements is a barrier to their use in clinics. We demonstrate that ultrasound elastography – a non-invasive, clinically established tool – can be used to measure spinal cord stiffness intraoperatively in canines with spontaneous spinal cord injury. In line with recent experimental reports, our data show that injured spinal cord has lower stiffness than uninjured cord. We show that the stiffness of hydrogels encapsulating a clinically relevant transplant population (olfactory ensheathing cells) can also be measured by ultrasound elastography, enabling synthesis of hydrogels with comparable stiffness to canine spinal cord injury. We therefore demonstrate proof-of-principle of a novel approach to stiffness-matching hydrogel-olfactory ensheathing cell implants to ‘real-life’ spinal cord injury values; an approach applicable to multiple biomaterial implants for regenerative therapies.
Book chapters on the topic "Stiffness comparable"
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Colombo, Francesco, Samuel Sonnino, Federico Mantovani, et al. "Laboratory Abrasion Tester to Estimate Tyre Grip and Cornering Stiffness." In Lecture Notes in Mechanical Engineering. Springer Nature Switzerland, 2024. http://dx.doi.org/10.1007/978-3-031-70392-8_81.
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AbstractIdentification of tyre grip is crucial for ensuring safety and performance. To develop new tyres matching the requirements for grip, extensive testing is required both indoor and outdoor, which is time-consuming and costly. Therefore, the possibility to assess their performance in laboratory before manufacturing a full tyre appears very attractive. On this purpose, the present paper compares the peak of the friction coefficient, evaluated using a Laboratory Abrasion Tester (LAT100) on two compounds and the grip assessed through MTS Flat-Trac machine tests on two full tyres having the same structure and made of the compounds tested on the LAT100. An ad hoc procedure for driving the test on the LAT100 and make them comparable with the full-tyre data was developed. A good correlation was found for the dependency of the friction coefficient on temperature and load, highlighting the possibility of using LAT100 tests to gain information about tyre performance, before the manufacturing of the full tyre.
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Grosse, Thomas, Ulrich Müller, Matthias Jakob, Florian Feist, Mathias H. Luxner, and Wolfgang Knoebl. "3d-Shaped High-Strength Parts from Partially Delignified and Densified Wood—Introduction of the Project HolzF3." In Zukunftstechnologien für den multifunktionalen Leichtbau. Springer Fachmedien Wiesbaden, 2024. https://doi.org/10.1007/978-3-658-45889-8_13.
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AbstractThis study explores the potential of wood-based materials in sustainable lightweight automotive applications. The research focuses on overcoming the challenge of balancing complex three-dimensional design with component stiffness and strength in crash-relevant vehicle structures. The study investigates a novel approach involving partial delignification and subsequent densification of wood, previously shown to significantly enhance mechanical properties in solid wood. The HolzF3 project applies this technique to chipboard materials (strands) and small-diameter birch and beech wood, which are typically used for energy production only. By utilizing smaller semi-finished products like strands, complex three-dimensional component shapes become feasible, with densification compensating for potential loss in mechanical performance. Initial results demonstrate the effectiveness of a two-step densification process in producing high-strength wood fractions from veneers and strands derived from small-diameter birch and beech roundwood. This process increases raw material density to 0.92-1.19 g/cmB3, while significantly improving tensile strength and stiffness. Notably, densified birch veneers achieved tensile strength up to 400 MPa and stiffness up to 40 GPa, comparable to industrially available veneers. The study concludes that this approach enables the utilization of previously undervalued wood fractions in high-quality material applications, particularly in the automotive industry. This innovation not only improves product sustainability and reduces COb footprint but also creates new opportunies for sustainable value-added processes in the mobility sector.
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Reichel, Vicky, Werner Berlin, and Klaus Dröder. "Process Chain for Functionally Integrated Structures Based on Continuous Fibre Reinforced Thermoplastic Sheets." In Zukunftstechnologien für den multifunktionalen Leichtbau. Springer Fachmedien Wiesbaden, 2024. https://doi.org/10.1007/978-3-658-45889-8_6.
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AbstractThermoforming enables the efficient processing of continuous fibre reinforced thermoplastic (CFRT) such as organo sheets into geometrically complex and structurally advantageous structures; however, resulting components are often hybrized through additional processes for an increased rigidity. For this, injection moulding is a widespread option, as it allows for the precise integration of plastic ribs into the thermoformed products, leading to improved structural integrity and mechanical stiffness [1, 2]. As thermoforming and injection moulding offer synergistic advantages, especially based on many related process steps, the processes can be successfully integrated [3]. When further manufacturing steps such as cutting are combined within this integrated process, the previously required handling steps are avoided entirely and the overall process cycle time can be reduced [4].Within the present research, the integration of multiple process steps into an integrative process chain is examined through a prototypical experimental setup. The investigated one-shot injection moulding mould (IMM) combines the thermoforming and trimming of the final contour as well as the injection moulding step within an index plate mould. This enables comparably short process cycles while maintaining part quality, such as the defined position of CFRT in edge contours. The process chain is validated and resulting demonstrator components are analyzed regarding the adhesion between CFRT and applied thermoplastics by applying tensile loads. Even in comparison to conventionally established processes, the investigated integrated process chain enables feasible results. Within the examined process parameters, the temperatures within the different system components significantly influence the overall part quality. Overall, the concept for an integrated process chain shows promise for further investigations, as it offers significant gains in overall process efficiencies through reduced handling steps and potential time savings.
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Suwal Laxmi P. and Kuwano Reiko. "Disk Transducer for stiffness measurement on granular materials." In Advances in Soil Mechanics and Geotechnical Engineering. IOS Press, 2015. https://doi.org/10.3233/978-1-61499-601-9-291.
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Small-strain stiffness is one of the prominent characteristics of geo-materials on analysis of deformation behavior. Elastic wave measurement technique is becoming stronger non-destructive tool than other technique. In this paper, authors have focused on the application of the flat surfaced transducer &lsquo;Disk transducer&rsquo;, enabling to measure both compression and shear wave on triaxial specimen. Disk transducer was built the University of Tokyo using piezo- ceramic element and encapsulated in the top cap and pedestal of small scaled triaxial apparatus then performed the tests. This paper presents the results of three sorts of granular materials, fine, medium and coarse sand, were investigated statically and dynamically at isotropic and anisotropic stress states in the laboratory. The elastic parameters obtained on the granular materials; Young's modulus (E) and shear modulus (G), obtained by statically and by means of disk transducer method were examined and compared. It was observed, the statically and dynamically obtained results are mutually comparable and in agreement with previous studies. It is also confirmed the elastic parameters are to be a unique function of stress states with experimental evidence.
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Solazzi, Luigi, Giuseppe Schinetti, and Riccardo Adamini. "Developed an Innovative Handbike Fork Made of Composite Material." In Studies in Health Technology and Informatics. IOS Press, 2022. http://dx.doi.org/10.3233/shti220861.
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In this research, the design of a new competitive handbike fork, made of a composite material, is presented. The study is based both on an early finite element analysis and on a CFD analysis of the characteristics and performance of a standard fork made of aluminum, allowing to define the loading and the flux conditions and to provide a design optimization of the fork. The model was later implemented iteratively with the properties of a carbon-fiber composite material. The results obtained show that the new model allows a weight and a drag force reduction and a downforce improvement, with a stiffness and a safety coefficient comparable to the standard aluminum fork.
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Stokes I.A.F., McBride C.A., and Aronsson D.D. "Intervertebral disc changes in an animal model representing altered mechanics in scoliosis." In Studies in Health Technology and Informatics. IOS Press, 2008. https://doi.org/10.3233/978-1-58603-888-5-273.
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The intervertebral discs become wedged and narrowed in a scoliosis curve, and this may be due in part to altered biomechanical environment. To study this, external rings were attached by percutaneous pins transfixing adjacent vertebrae in 5-week-old Sprague-Dawley rats and four permutations of mechanical conditions (4 groups of animals) were compared: (A) 15 degrees Angulation, (B) Angulation with 0.1 MPa Compression, (C) 0.1 MPa Compression, and (D) Reduced mobility. These altered mechanical conditions were applied for 5 weeks. After 5 weeks, disc narrowing at the intervention levels was evident in micro-CT images. Average disc space loss as a percent of the initial values over the 5 weeks was 19%, 28%, 22% and 20% four groups listed above. Increased lateral bending stiffness relative to within-animal controls was also observed at all groups. The minimum stiffness was recorded at an angle close to the in vivo value, indicating that angulated discs had adapted to the imposed deformity. In the angulated and compressed discs there was a small difference in the amount of collagen crimping in the disc annuli between concave and convex sides. All experimental interventions produced substantial changes in the intervertebral discs of these growing animals. &lsquo;Reduced mobility&rsquo; was present in all interventions, and the changes in the discs with reduced mobility alone were comparable with those in loaded and angulated discs. This suggests that imposed reduced mobility is the major source of disc changes, and may be a factor in disc degeneration in scoliosis. Further studies are in progress to characterize gene expression, matrix protein synthesis and composition in these discs.
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Chairi, Mohamed, Jalal El Bahaoui, Issam Hanafi, Francisco Mata, and Guido Di Bella. "Composite Materials: A Review of Polymer and Metal Matrix Composites, Their Mechanical Characterization, and Mechanical Properties." In Next Generation Fiber-Reinforced Composites - New Insights [Working Title]. IntechOpen, 2023. http://dx.doi.org/10.5772/intechopen.106624.
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Unlike conventional materials, composites have become an optimal option for a range of modern, industrial, clinical, and sports applications. This is combined with their noteworthy physical, thermal, electrical, and mechanical properties, as well as low weight and cost investment funds in certain cases. This review article attempts to give an overall outline of composite materials, regularly polymer-matrix composites (PMCs) and metal-matrix composites (MMCs). Polypropylene (PP) polymer and aluminum alloy were selected as matrices for this concentrate in light of their appealing properties and their use in different applications. Various studies address the different build-up materials, material handling, and the various properties. Mechanical characterization is an important cycle process for the development and design of composite materials and their components. It includes the determination of mechanical properties, for example, stiffness and strength according to standard test techniques (i.e., tensile, compression, and shear test strategies) distributed by the ASTM and EN ISO associations. Comparable to the determination of fatigue strength and fatigue life for composite materials. With respect to mechanical properties of composite materials, this paper reports several variables and limitations that affect mechanical property estimates, including material constituents, manufacturing process, test parameters, and environmental conditions.
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Wilkinson S., Brosse A., Fenton C.H., Hosseini Kamal R., Jardine R.J., and Coop M.R. "An integrated geotechnical study of UK mudrocks." In Proceedings of the 15th European Conference on Soil Mechanics and Geotechnical Engineering. IOS Press, 2011. https://doi.org/10.3233/978-1-60750-801-4-305.
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Mudrocks evolve from soft, predominantly marine sediments, deposited with very high moisture contents, to fissile shales or cemented claystones. The eventual structure of each mudrock is dependant both on the initial condition of sedimentation and the changing environments into which they are placed as they evolve. The anisotropy, strength and stiffness of each mudrock are a reflection of its microstructure at the time of testing. For example, deep burial eventually produces highly aligned fabrics and calcite-rich fluid-flow produces highly cemented materials. As these fine-grained sediments are subject to increasing depth of burial they will pass through a stiff soil &ndash; weak rock transition, eventually becoming a lithified sedimentary rock. The Jurassic and Cretaceous mudrocks of the UK were deposited in similar, low-energy geological environments. As well as their depositional setting, the structure of these materials is controlled by their differing sediment sources, climatic conditions, and postdepositional histories. In particular, the detailed burial and subsequent uplift history experienced by each mudrock will determine how its original depositional structure is altered. The mechanical behaviour of younger mudrocks in the UK, such as the Eocene London Clay, has been studied extensively (Geotechnique, 2007). This paper presents a comparable study of the material properties of the older, more deeply buried, Gault, Kimmeridge, Oxford and Lias Clays. The effect of microstructure, and hence geological history, on the geotechnical properties of these mudrocks are studied in detail. The programme of investigations undertaken by a team from Imperial College London included: detailed geological evaluation, in situ testing, high quality sampling, index tests, advanced mechanical tests and quantification of microstructure through innovative scanning electron microscope fabric analysis.
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Tammemagi, Hans. "Containment, Encapsulation, and Treatment." In The Waste Crisis. Oxford University Press, 2000. http://dx.doi.org/10.1093/oso/9780195128987.003.0013.
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Just as a chain is only as strong as its weakest link, a landfill will only function as well as its weakest component. The most important “links” of a landfill are the cover and bottom liner that provide watertightness. Because of their critical significance, this chapter is devoted to studying the materials from which these barriers are constructed and how they are emplaced. We also look at ways in which the wastes themselves can be converted to forms that are more suitable for long-term disposal. Polymeric membranes, more commonly known as geomembranes or flexible membrane liners, are widely used in both the cover and the bottom liner systems. These synthetic materials have gained acceptance as barriers at landfills because they exhibit very low permeabilities, they are resistant to many chemicals, and they can often be installed for less cost than comparable clay liners. The polymeric membranes used in landfills consist of synthetic plastic or rubber sheets that are joined together in the field using solvents, adhesives, or welding processes to form continuous liners. There are several polymers and compounds that are used, and these have a wide range of material properties. The most common materials are high-density polyethylene (HDPE), polyvinyl chloride (PVC), chlorinated polyethyle , and butyl rubber. Of these, HDPE is most commonly used for landfills, in part because of its documented resistance to a wide range of chemicals. Its thickness ranges from about 0.75 to 3 millimeters (30 to 120 mils). Many polymers can be made in either vulcanized form (treated with sulphur and heat to give strength by building crosslinks between the rubber polymer molecules) or unvulcanized (thermoplastic) form. Vulcanized liners tend to be stronger and more chemically resistant, but thermoplastic versions of compounds like chlorinated polyethylene are more commonly used because they are easier to seam and repair in the field. A number of additives can be introduced to improve characteristics such as stiffness or flexibility, resistance to fungicides and biocides, and resistance to ultraviolet light and ozone.
Conference papers on the topic "Stiffness comparable"
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Fujikawa, Yasunori, Ryota Matsui, and Taichiro Okazaki. "Influence of hysteretic models on viscous damping in nonlinear response history analysis of buildings." In IABSE Symposium, Tokyo 2025: Environmentally Friendly Technologies and Structures: Focusing on Sustainable Approaches. International Association for Bridge and Structural Engineering (IABSE), 2025. https://doi.org/10.2749/tokyo.2025.3303.
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<p>In time-history response analysis of elastic-plastic systems, common viscous damping models yield unintended spurious damping forces. A previous study exhibited thirteen different damping models resulted in different elastic-plastic response of a 5-degree-of-freedom system assigning a bi-linear hysteresis model. This paper expands on that work by analyzing the impact of these damping models on the elastic-plastic response of systems incorporating five distinct hysteresis models. The number of rapid stiffness changes significantly increases the potential of generating large spurious damping forces. The tangent-stiffness-proportional Rayleigh model, with coefficients updated based on the elastic-plastic state step-by-step, failed to retain damping ratios close to target values. The Rayleigh model with a diminished mass-proportional term, produced responses comparable to those obtained using modal damping with coefficient updated step-by-step.</p>
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Brown, Avery, Bhavya Patel, Noah Robertson, et al. "Blade Stiffened Carbon/Epoxy Panels with Longitudinally Tapered Acoustic Black Holes for Vibration Reduction." In Vertical Flight Society 81st Annual Forum and Technology Display. The Vertical Flight Society, 2025. https://doi.org/10.4050/f-0081-2025-276.
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Carbon/epoxy stiffened panels are being increasingly used in transport rotorcraft. The reduced mass density and high stiffness of carbon/epoxy composites can lead to higher levels of vibration relative to comparable metallic structures, which themselves can have vibrations and interior noise high enough to damage the hearing of crew and passengers. The current investigation explores a method to reduce the vibration of carbon/epoxy stiffened panels by introducing thickness tapers known as acoustic black holes (ABHs). The ABH feature is integrated into either the stiffeners or plate of a representative stiffened panel configuration. A finite element (FE) parametric study was used to guide designs that reduce the vibration of the panel without compromising the compressive buckling capability or mass of the panel. FE studies showed that a 30 ply to 12 ply thickness taper longitudinally oriented in the blade stiffener can reduce vibrations and increase compressive buckling capability. Carbon/epoxy panels were manufactured using a low-cost out-of-autoclave material with simple molding. Experimental testing concluded that integrating the ABH into the stiffeners longitudinally helped to reduce the broadband vibration by 5 dB and increase the buckling load (+4.3%) and collapse load (+16.5%) without increasing the mass greatly compared to a traditional baseline design.
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Niemiec, Robert, Farhan Gandhi, and George Jacobellis. "Reversible Airfoil for Stopped Rotors in High Speed Flight." In Vertical Flight Society 70th Annual Forum & Technology Display. The Vertical Flight Society, 2014. http://dx.doi.org/10.4050/f-0070-2014-9426.
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This study starts with the design of a reversible airfoil rib for stopped-rotor applications, where the sharp trailing-edge morphs into the rounded leading-edge, and vice-versa. A NACA0012 airfoil is approximated in a piecewise linear manner and straight, rigid outer profile links used to define the airfoil contour. The end points of the profile links connect to control links, each set on a central actuation rod via an offset. Chordwise motion of the actuation rod moves the control and the profile links and reverses the airfoil. The paper describes the design methodology and evolution of the final design, based on which two reversible airfoil ribs were fabricated and used to assemble a finite span reversible rotor/wing demonstrator. The profile links were connected by Aluminum strips running in the spanwise direction which provided stiffness as well as support for a pre-tensioned elastomeric skin. An inter-rib connecter with a curved-front nose piece supports the leading-edge. The model functioned well and was able to reverse smoothly back-and-forth, on application and reversal of a voltage to the motor. Navier Stokes CFD simulations (using the TURNS code) show that the drag coefficient of the reversible airfoil (which had a 13% maximum thickness due to the thickness of the profile links) was comparable to that of the NACA0013 airfoil. The drag of a 16% thick elliptical airfoil was, on average, about twice as large, while that of a NACA0012 in reverse flow was 4-5 times as large, even prior to stall. The maximum lift coefficient of the reversible airfoil was lower than the elliptical airfoil, but higher than the NACA0012 in reverse flow operation.
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Jung Soo Kim, Ko Keun Kim, Hyun Jae Baek, and Kwang Suk Park. "Comparable parameter related to arterial stiffness in blood pressure estimation method." In 2008 International Conference on Technology and Applications in Biomedicine (ITAB). IEEE, 2008. http://dx.doi.org/10.1109/itab.2008.4570557.
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Plaskocinski, Tomasz, Jianling Xiao, Mohammad Biabanifard, Saydulla Persheyev, and Andrea Di Falco. "Holographic optical metasurfaces with high trap stiffness." In Optical Manipulation and Its Applications. Optica Publishing Group, 2023. http://dx.doi.org/10.1364/oma.2023.atu2d.3.
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Optical metalenses have been used to trap particles on-chip, albeit with low trapping efficiency. We present a low-footprint metasurface-enabled holographic trapping scheme with performance comparable to that of high numerical aperture objectives.
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Rivin, Eugene I., and Panchal Pankach. "Stiffness Enhancement of Metallic Beam-Like Components." In ASME 1996 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 1996. http://dx.doi.org/10.1115/imece1996-0153.
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Abstract Stiffness is an important design criterion. Since bending deformations of structural components are much larger than tension/compression deformations under comparable loads, enhancement of bending stiffness of beam-like components is an important problem. Conventional techniques for stiffness enhancement (beefing up, optimization, use of high Young’s modulus materials) frequently do not achieve the desired results. The paper describes a novel approach to bending stiffness enhancement based on the inverse buckling effect. The beam is composed of the structural external member having an axial hole which is plugged and filled with a fusible metal alloy expanding during solidification thus stretching the external member and enhancing its stiffness. Experimental study resulting in 40% increase in bending stiffness is described.
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Xiong, Jerry, and Michael P. Hennessey. "Stiffness Matrix Evaluation for a Dual-Reeved Tensile Truss." In ASME 2013 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/detc2013-12140.
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Researchers have evaluated the stiffness matrix for different robots and structures, including the Stewart platform style tensile truss. However, none of the configurations analyzed to date involve “dual-reeving,” a common industrial rigging technique whereby cables are spatial loops, vs. open-loop elements, such as those represented by simple line segments. The 4-node/4-loop kinematic configuration analyzed contains 4 symmetric nodes and loops and provides competition for a comparable-sized Stewart platform from the perspective of directional stiffness. Additionally, like the Stewart platform, only a modest amount of off-diagonal compliance matrix elements are present, which from a practical and intuitive point of view, can be advantageous. The methodology used and illustrated in detail is easily generalized to adapt to more involved configurations. Numerical results are obtained for a specific example and compared with those from a Stewart platform. Lastly, some experimental results compare favorably with those derived analytically and evaluated numerically.
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Muder, Sean, Robert Haynes, and Erian Armanios. "Analysis of the Extension-Twist Coupling in Hygrothermally Stable Star Beam Composites." In ASME 2011 International Mechanical Engineering Congress and Exposition. ASMEDC, 2011. http://dx.doi.org/10.1115/imece2011-65318.
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An approximate analytical model is utilized to examine the extension-twist coupling and torsional stiffness properties of star beams constructed with a new family of hygrothermally stable optimized stacking sequences. The relationship between axial force and the twist rate is used to quantify the results. The results show that there is a decrease in torsional rigidity corresponding to an increase in extension-twist coupling. The new stacking sequences allow for the addition of more substrips while maintaining comparable levels of extension-twist coupling with beams constructed from prior benchmark layups. This results in higher levels of torsional stiffness for comparable levels of extension-twist coupling in star beams made of the new optimized stacking sequences.
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Al-Shudeifat, Mohammad A. "New Design of Magnetic Nonlinear Energy Sink for Shock Mitigation in Dynamic Structures." In ASME 2013 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/detc2013-12461.
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Targeted energy transfer is of significant concern in the nonlinear energy sinks (NESs) used for shock (blasts, earthquakes) mitigation in small and large scale dynamic structures which saves human and equipment. The NES is a light-weighted device (<10% of the whole structure mass) which passively absorbs and rapidly dissipates a considerable portion of the initial shock energy induced to the linear dynamic structure. The proposed new design is based on utilizing the permanent magnets that generate a nonlinear repulsive magnetic force which is nearly equivalent to the required stiffness-based NES force. Using magnets instead of stiffness-based elastic materials yields a flexible and compact design of comparable efficiency with the stiffness-based existing NESs. This proposed design is expected to have wide range of applications for either small systems (Aircraft wings) or large scale dynamic structures (large scale buildings or towers). Hence, symmetric and asymmetric designs of magnet-based NESs are considered here to achieve the aimed optimum performance for shock mitigation. The results of the numerical simulation of the symmetric magnet-based NES are found to be comparable to the stiffness-based NES. However the asymmetric magnet-based design has shown better performance than the stiffness-based NES which is promising for the real life applications.
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Costic, Ryan S., Joanne E. Labriola, Mark W. Rodosky, and Richard E. Debski. "Stiffness Comparison of Coracoclavicular Ligament and Anatomic Reconstruction Complexes: Overall and Individual Complex Components." In ASME 2003 International Mechanical Engineering Congress and Exposition. ASMEDC, 2003. http://dx.doi.org/10.1115/imece2003-43011.
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The stiffness of the coracoclavicular ligaments and their surgical replacments have previously been reported; however, the mechanism of failure and procedures for repair include both the clavicle and coracoid process which have not been investigated. Therfore, this study utilized a physiolgogic mechanism of injury to compare the stiffness of the coracoclavicluar ligament and anatomic reconstruction complexes, both overall and individual complex components. After dislocation of the coracoclavicular ligament complex, a 40% decrease of the clavicle stiffness was observed along with a more comparable stiffness of the reconstruction tendon graft to the intact coracoclavicular ligaments compared to current repair materials. These findings suggest all components of the coracoclavicluar complex following dislocation should be considered in selection of rehablilation protocols or surgical procedures.
Reports on the topic "Stiffness comparable"
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Qamhia, Issam, Erol Tutumluer, and Han Wang. Aggregate Subgrade Improvements Using Quarry By-products: A Field Investigation. Illinois Center for Transportation, 2021. http://dx.doi.org/10.36501/0197-9191/21-017.
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This report presents a case study for constructing aggregate subgrade improvement (ASI) layers using quarry by-product aggregates (QBA), a quarry mix of large primary crushed rocks (PCR) and sand-sized quarry fines. The construction took place at Larry Power Road in Bourbonnais Township in Kankakee County, Illinois, where the Illinois Department of Transportation placed two QBA mixes. The first mix (QBA_M1) consisted of 45% quarry by-products and 55% railroad ballast–sized 3×1 PCR. The second mix (QBA_M2) consisted of 31% and 69% quarry by-products and PCR, respectively. Two conventional ASI sections were also constructed conforming to Illinois Department of Transportation’s CS02 gradation. All sections consisted of a 9 in. (229 mm) QBA/PCR layer topped with a 3 in. (76 mm) dense-graded capping layer. Laboratory studies preceded the construction to recommend optimum quarry by-product content in the QBA materials and construction practice. The Illinois Center for Transportation research team monitored the quality and uniformity of the construction using nondestructive testing techniques such as dynamic cone penetrometer, lightweight deflectometer, and falling weight deflectometer. The segregation potential was monitored by visual inspection and imaging-based techniques. Short-term field evaluation of the constructed QBA layers, particularly QBA_M2 with a 31% quarry by-product content, showed no evidence of abnormal segregation and did not jeopardize the structural integrity of the QBA ASI layers, which had slightly lower but comparable strength and stiffness profiles to the conventional ASI sections. The use of QBA materials in ASI was field validated as a sustainable construction practice to provide stable pavement foundation layers.
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El Badawy, Amro, and Ashraf Rahim. Evaluation of Nanoclay Additives for Improving Resistance to Moisture Damage in Hot Mix Asphalt (HMA). Mineta Transportation Institute, 2023. http://dx.doi.org/10.31979/mti.2023.2151.
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Transportation has an enormous impact on the U.S. economy and on the lives of all Americans. Many modes of transportation rely on pavement, but pavement conditions deteriorate over time because of the combined effects of traffic and climate. Exposure to moisture often causes premature failure of asphalt pavements as it reduces the stiffness of the asphalt and enables stripping of the asphalt from the aggregate. This research evaluates the effectiveness of clay nanomaterials (i.e., nanoclays) in improving the resistance of hot mix asphalt (HMA) to moisture damage and compares the enhancement results to anti-stripping additives commonly used in pavement construction. Two types of surface-modified nanoclay, lime-treated aggregate, and two amine-based liquid antistripping agents (HP Plus and LOF 6500) were evaluated for improving HMA’s moisture resistance. All additives tested for reducing moisture damage resulted in dry and wet tensile strength of the modified mixes higher than the minimum specified by Caltrans 2018 Standard Specifications (100 psi for dry tensile strength and 70 psi for wet tensile strength). The Tensile Strength Ratio (TSR) of all HMA modified mixes was higher than 0.80, which is the minimum specified by the Superpave mix design method (Asphalt Mix Design Methods MS-2, Asphalt Institute) and exceeded the TSR of the control mix. The TSR for HMA mixes modified using nanoclays were comparable to those for HMA mixes modified using liquid antistripping and lime slurry treated aggregate. Liquid antistripping agents tested herein were the least costly additive at an approximately $2.0/ton added cost. This research can be used to better understand pavement deterioration to enable the most efficient and cost-effective construction and preservation of our nation's critical transportation infrastructure.
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AN INNOVATIVE STEEL INTERLOCKING TIE SYSTEM FOR COMPOSITE WALLS IN MODULAR INTEGRATED CONSTRUCTION. The Hong Kong Institute of Steel Construction, 2025. https://doi.org/10.18057/ijasc.2025.21.1.8.
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This paper proposes an innovative steel interlocking tie system for composite walls in reinforced concrete Modular Integrated Construction (MiC), eliminating the need for tie bolts penetrating precast sidewalls. This design facilitates complete factory interior fitting and minimizes on-site disruption to internal finishes. Experimental tests for the proposed steel interlocking system have been conducted and the advanced finite element models for the investigation of the system have been developed. Six case studies comparing density-based topology optimization and empirical optimization using finite element analysis are presented. The empirical optimization demonstrates high computational efficiency, as it does not require elaborate iterative analysis and produces a design comparable to that from topology optimization. The final optimized shape has 49.8% of the weight of the initial design and an average mechanical performance difference of 3.02% compared to the topology optimization.Six case studies comparing density-based topology optimization and empirical optimization using finite element analysis reveal that empirical optimization achieves comparable mechanical performance with significantly reduced computational cost and time. Furthermore, the system's adaptability is demonstrated through adjustments to interlocking tie dimensions accommodating to accommodate varying tying positions and wall thicknesses, effectively controlling wall deformations and meeting strength and stiffness requirements under the requirements of certain wall deformations, strength and stiffness. A successful real-world application in a Hong Kong MiC project is also presented, offering and offers practical guidance for future MiC implementations.