To see the other types of publications on this topic, follow the link: Fracture of specimen with notches.
Journal articles on the topic 'Fracture of specimen with notches'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 journal articles for your research on the topic 'Fracture of specimen with notches.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse journal articles on a wide variety of disciplines and organise your bibliography correctly.
1
Kim, Duck Hoi, Jae Hoon Kim, and Soon Il Moon. "Analysis of Failure Criterion for Combustion Chamber with Notch Using Effective Distance." Key Engineering Materials 297-300 (November 2005): 722–27. http://dx.doi.org/10.4028/www.scientific.net/kem.297-300.722.
Full textAbstract:
In this study, the intrinsic static/dynamic fracture toughness of Al 7175-T74 is evaluated from the apparent static/dynamic fracture toughness of a notched specimen. A critical average stress fracture model is suggested to establish the relationship for predicting the intrinsic fracture toughness from the apparent fracture toughness of a notched specimen. The critical average stress fracture model is established using the relationship between the notch root radius and the effective distance calculated by finite element analysis. The effective distance is the major characteristic describing stress distributions ahead of the notch tip. Therefore, the effective distance can be used to evaluate the behavior of structures containing notches. In this study, effective distance is applied to estimate the failure criterion for the combustion chamber with a notch. It is concluded that the true fracture toughness can be estimated from test results of apparent fracture toughness measured by using a notched specimen. Also, the effective distance can be used to evaluate the failure criterion of structures with notches.
2
KIM, DUCK-HOI, JAE-HOON KIM, YOUNG-SHIN LEE, et al. "STUDY ON DYNAMIC FRACTURE CHARACTERISTICS AND APPLICATION TO THE STRUCTURES OF ADVANCED GLASS CERAMIC." International Journal of Modern Physics B 20, no. 25n27 (2006): 3908–13. http://dx.doi.org/10.1142/s021797920604057x.
Full textAbstract:
In this study, the intrinsic static/dynamic fracture toughness of advanced glass ceramic is evaluated from the apparent static/dynamic fracture toughness of a notched specimen. A critical average stress fracture model is suggested to establish the relationship for predicting the intrinsic fracture toughness from the apparent fracture toughness of a notched specimen. The critical average stress fracture model is established using the relationship between the notch root radius and the effective distance calculated by finite element analysis. The effective distance is the major characteristic describing stress distributions ahead of the notch tip. Therefore, the effective distance can be used to evaluate the behavior of structures containing notches. It is concluded that the true fracture toughness can be estimated from test results of apparent fracture toughness measured by using a notched specimen. Also, the effective distance can be used to evaluate the failure criterion of structures with notches.
3
Bura, Elżbieta, and Andrzej Seweryn. "Fracture Initiation in Notched Specimens Subjected to Compression: Strain Rate Effect." Materials 13, no. 11 (2020): 2613. http://dx.doi.org/10.3390/ma13112613.
Full textAbstract:
This paper shows the results of an experimental investigation on fracture in polymethyl methacrylate (PMMA) notched specimens subjected to compression (with unloading) including different strain rates. Three types of notches were used. Flat specimens were weakened by two types of V-notches and U-notches. Additionally, two specimen thicknesses were used (9.7 and 14.5 mm). The load was carried out at the strain rate of 8 × 10−4, 4 × 10−3, and 2 × 10−2 s−1 and the unloading stage was conducted ten times faster, i.e., 8 × 10−3, 4 × 10−2, and 2 × 10−1 s−1, respectively. By using a PHANTOM high-speed camera, fracture initiation moments and locations were indicated. Two types of crack were observed and distinguished as A-type and B-type. The first was formed by the contact stress of the closing notch surfaces, while the latter was formed by the residual stresses during the unloading stage. The type of notch, specimen thickness, and the strain rate have a significant influence on the fracture process. The strain rate has a large impact on the critical load value, which determines the fracture initiation, but does not affect the location and shape of the crack. The strain rate effect usually disappears with increasing specimen thickness.
4
Guo, Qifeng, Xinghui Wu, Meifeng Cai, and Shengjun Miao. "Experimental Study on the Effect of Offset Notch on Fracture Properties of Rock under Three-Point Bending Beam." Advances in Materials Science and Engineering 2020 (February 8, 2020): 1–7. http://dx.doi.org/10.1155/2020/2781928.
Full textAbstract:
To investigate the effects of offset notch on the fracture properties of rock beam under bending load, granite beam specimens with “one single offset notch” and “central and offset double notches” are made. A series of three-point bending beam tests on the specimens are carried out by controlling the displacement rate of central notch. The whole load-displacement (P-CMOD) curves are obtained. Experimental results show that the larger the distance between the offset notch and beam central is, the larger are the peak load and nominal strength of the specimen. The peak load and nominal strength for the “central and offset double notches” specimens are both larger than those for the “single central notch” specimen. A fracture model considering the effect of offset notch is developed, and the relationship between the offset notch parameter, tensile strength, and fracture toughness is established.
5
Azizi, Muhammad Azim, Mohd Faiz Mohd Ridhuan, Mohd Zakiyuddin Mohd Zahari, Sharafiz Abdul Rahim, and Muhammad Amin Azman. "Peridynamic Model for Tensile Elongation and Fracture Simulations of Polymethyl Methacrylate Notched Specimens." Applied Mechanics and Materials 909 (September 28, 2022): 11–28. http://dx.doi.org/10.4028/p-2z0841.
Full textAbstract:
This paper presents the peridynamic (PD) numerical model for simulating a tensile test until total fracture for a brittle polymeric material namely polymethyl methacrylate (PMMA). U-notched and V-notched specimens were used to investigate the effect of the notches on the elongation and fracture of PMMA. The tensile elongation of PMMA exhibits nonlinearity with respect to the applied load, while the fracture occurs when the material stress has reached the ultimate tensile stress of the material. Similar elongation and fracture properties were applied on PD simulations. Two types of elongation equation are used namely brittle and ductile equations to form PD-brittle and PD-ductile models. The published experimental data of tensile fracture test on notched PMMA specimens are used as reference to validate the simulations of the PD models. The PD numerical force-extension curves have good quantitative similarity for V-notched specimen but adequate quantitative similarity for U-notched specimen. As for the quality of the fractured specimen shape, the PD simulations have good similarity for the V-notched specimen but adequate similarity for the U-notched specimen. The plot of the internal force distribution from the simulations of PD shows good qualitative similarity to the plot of the stress distribution from the published data of FEM in terms of stress concentration. From the PD results, it is observed that the PD-ductile model has better capability in producing accurate simulation of the notched specimens than the PD-brittle model.
6
Zebri, O., H. El Minor, and A. Bendarma. "Evolution of Tenacity in Mixed Mode Fracture – Volumetric Approach." Mechanics and Mechanical Engineering 22, no. 4 (2020): 931–38. http://dx.doi.org/10.2478/mme-2018-0073.
Full textAbstract:
AbstractIn fracture mechanics most interest is focused on stress intensity factors, which describe the singular stress field ahead of a crack tip and govern fracture of a specimen when a critical stress intensity factor is reached. In this paper, stress intensity factors which represents fracture toughness of material, caused by a notch in a volumetric approach has been examined, taking into account the specific conditions of loading by examining various U-notched circular ring specimens, with various geometries and boundary conditions, under a mixed mode I+II. The bend specimens are computed by finite element method (FEM) and the local stress distribution was calculated by the Abaqus/CAE. The results are assessed to determine the evolution of the stress intensity factor of different notches and loading distances from the root of notch. This study shows that the tenacity is not intrinsic to the material for all different geometries notches.
7
Torabi, Ali Reza, Mahdi Jabbari, Javad Akbardoost, and Sergio Cicero. "A Modified Mean Stress Criterion for Considering Size Effects on Mode I Fracture Estimation of Rounded-Tip V-Notched Polymeric Specimens." Polymers 14, no. 7 (2022): 1491. http://dx.doi.org/10.3390/polym14071491.
Full textAbstract:
The aim of this paper is to assess the size and geometry effects on the mode I notch fracture toughness of polymeric samples containing rounded-tip V-shaped (RV) notches (V-notch with a finite radius at the notch tip). First, using a large number of fracture tests on an RV-notched Brazilian disk and semi-circular bending polymeric samples with four different sizes, the size-dependent values of the notch fracture toughness are obtained. Then, the mean stress criterion is modified for characterizing the size-dependency of notch fracture toughness in polymeric samples. The resulting modified mean stress criterion considers higher order terms of the stress field when calculating the fracture process zone length around the tip of the defect. Additionally, the critical distance rc is assumed to be associated with the specimen size and a formula containing fitting parameters is utilized for considering this trend of rc. The comparison between the values of notch fracture toughness obtained from experiments and those predicted by the modified mean stress criterion shows that the suggested approach can provide accurate estimations of size-dependent values of notch fracture toughness in polymeric specimens containing RV notches.
8
Xiao, Pan, and Haining Li. "Acoustic Emission Behavior of TATB Based PBX during Uniaxial Compression Deformation." Journal of Physics: Conference Series 2478, no. 3 (2023): 032008. http://dx.doi.org/10.1088/1742-6596/2478/3/032008.
Full textAbstract:
Abstract In order to study the feasibility of acoustic emission technology for the damage and fracture monitoring of TATB-based PBX materials and components, the acoustic emission characteristics of notched and unnotched specimens under uniaxial compression were studied. The results of uniaxial compression and step-cycle compression experiments of unnotched specimens showed that there were few AE hits with low amplitude under low strain stage and many AE hits were generated when the specimen failed. In addition, the Kaiser effect is applicable at the low load stage. In addition, there were less AE hits in initial loading stage for the specimen with notches, which may be caused by machining force. However, very strong AE hits were generated in the specimen with notches before macroscopic fracture occurred. Acoustic emission technology can be used to determine whether macroscopic cracks were generated in TATB-based PBX structures in the experiment.
9
Han, Xiangyu, Qilong Zhao, Bin Jia, Jinqiao Liu, Qionglin Li, and Quan Zhang. "A Method for Determining the Fracture Toughness of Shotcrete Materials Subjected to Freeze–Thaw Cycles." Materials 18, no. 1 (2025): 171. https://doi.org/10.3390/ma18010171.
Full textAbstract:
Defects can be introduced into shotcrete materials after a few freeze–thaw cycles, which has a significant influence on the fracture performance of shotcrete. In this study, a series of shotcrete specimens with varying sizes, geometries, and initial crack lengths were prepared to investigate the fracture properties of notched shotcrete under freeze–thaw conditions. Considering the effects of specimen boundaries and material microstructure, a linear closed-form solution was proposed to determine the fracture toughness of frost-damaged shotcrete. The fracture toughness was found to be a reliable material constant, independent of specimen geometry variations. Results from three-point bending (3PB) tests show that freeze–thaw cycles severely weaken the fracture toughness of shotcrete, which is consistent with CT scan images of the damaged microstructure of the shotcrete specimens. Moreover, specimens with longer initial notches exhibited more severe freeze–thaw damage, which should be carefully considered in practical engineering assessments. These findings highlight the critical importance of considering freeze–thaw effects and notch length when evaluating the durability of shotcrete in cold region applications.
10
Wang, Ze Xing, Jin Hua Jiang, and Nan Liang Chen. "Notch Size and Loading Rate on the Tensile Behavior of Woven Fabric Reinforced Flexible Composite with Symmetrical Double Edge Notch." Applied Mechanics and Materials 341-342 (July 2013): 49–53. http://dx.doi.org/10.4028/www.scientific.net/amm.341-342.49.
Full textAbstract:
In order to investigate the effects of lager notch ratio (2α/W) and loading rate on the tensile behavior of woven fabric reinforced flexible composites, in this study, fracture mechanism and tensile strength of finite woven fabric-reinforced flexible composite materials with a through-the-thickness symmetrical located double edge notches is experimentally investigated, and the effects of notch size, loading rate on the tensile properties of notched specimen are analyzed. The results show that the woven fabric reinforced flexible composites exhibit notch sensitivity and loading rate dependent. These results play an important role in predicting strength and evaluating the lifetime of textile reinforced flexible composite materials with double edge notches.
11
Trant, Claire, Nigel Martin, Mark Dixon, Edward Saunders, Trevor Lindley, and David Dye. "The effect of notch size on fatigue crack threshold and propagation in cast gamma titanium aluminide." MATEC Web of Conferences 321 (2020): 08006. http://dx.doi.org/10.1051/matecconf/202032108006.
Full textAbstract:
Cracks were initiated and grown from notched specimens with notch lengths of 0.03 (FIB), 0.06, 0.1 and 0.5 mm (diamond blade), in cast gamma titanium aluminide at 400 oC. Specimens with longer 0.1 and 0.5 mm notches initiated from the notch and show no effect from initial notch size on either crack growth threshold or propagation. Specimens with shorter 0.03 and 0.06 mm notches initiated naturally, cracking from microstructural features away from the notch. The fracture surfaces of these specimens were characterised to distinguish areas of initiation, fatigue and overload. Multiple initiation sites were observed on these fracture surfaces. It is inferred that, for this alloy and process route, microstructural initiation is dominant where notches are less than ~100 µm in size.
12
Toribio, Jesús, Francisco-Javier Ayaso, and Rocío Rodríguez. "Tensile Fracture Behaviour of Prismatic Notched Specimens of Cold Drawn Pearlitic Steel: A Macro- and Micro-Approach." Materials 18, no. 8 (2025): 1690. https://doi.org/10.3390/ma18081690.
Full textAbstract:
This paper focuses on the study of the tensile fracture behaviour of prismatic notched specimens of cold drawn pearlitic steel, providing a macro- and micro-approach. Two types of notched samples with very different notch radius (sharp and blunt notches, PAA and PCC) and the same notch depth were studied, thereby allowing a study of the fracture behaviour under different levels of stress triaxiality (constraint) in the experimental specimen. The studied samples are machined from pearlitic steel wires taken from a real cold drawing chain, analysing the entire drawing process, from the initial base material (hot rolled bar; not cold drawn at all) to the final commercial product (prestressing steel wires; heavily cold drawn), including two intermediate stages in the manufacture chain. The aforesaid specimens were subjected to tensile fracture tests and analysed at macroscopic and microscopical level using the scanning electron microscope (SEM), thereby obtaining micrographs of the different areas appearing in the specimens under study and assembling full micro-fracture maps (MFMs) of the fractured area. The aim of the research is to analyse the macro- and microscopic changes produced by the variation in stress triaxiality state (constraint), along with the different fracture processes. The first relevant finding is the increase in fracture path deflection for higher drawing degrees, and for greater triaxiality levels associated with sharp notches. Another finding is the variation in area of the different fracture zones, i.e., outer crown (OC), fracture process zone (FPZ) and intermediate zone (ZINT), which are characterised by their specific micro-mechanisms, micro-void coalescence (MVC), cleavage (C) and special (large) micro-void coalescence (MVC*). The higher the stress triaxiality level, the larger the area occupied by the ZINT in the fracture process. The fracture behaviour tends to unify along with the degree of drawing, with less dependence on the state of triaxiality imposed on heavily drawn wires. Results have been obtained in which the increase in triaxiality, imposed by the smaller radius of curvature of the notch (sharp notch), as well as the greater degree of drawing of the wires, cause the fracture process to place the FPZ at the notch tip. It is demonstrated that the variation in stress triaxiality and the drawing degree can generate different locations of the fracture initiation zone (FPZ).
13
Filipescu, Hannelore, Cristiana Caplescu, and Niculai Pasca. "Assessment of UMTS and Averaged SED Fracture Criteria for U-Notched Specimens." Key Engineering Materials 577-578 (September 2013): 113–16. http://dx.doi.org/10.4028/www.scientific.net/kem.577-578.113.
Full textAbstract:
A set of mixed-mode I/II fracture tests was carried out on a polyurethane material. Using a single edge notched bend (SENB) type specimen, containing straight and respectively inclined U notches, the full range from pure mode I to dominant mode II was achieved. Two different fracture criteria were employed for the prediction of the fracture conditions: the UMTS criterion and the averaged SED criterion. Using these two criteria a set of curves were derived in terms of the fracture load vs. notch radius. The agreement between the experimental results and those predicted based on these two criteria is discussed finally.
14
Talebi, Hossein, Mohsen Askari, Majid Ayatollahi, and Sergio Cicero. "VO-Notches Subjected to Tension–Torsion Loading: Experimental and Theoretical Fracture Study on Polymeric Samples." Polymers 15, no. 11 (2023): 2454. http://dx.doi.org/10.3390/polym15112454.
Full textAbstract:
In this research, the fracture behavior of brittle specimens weakened by V-shaped notches with end holes (VO-notches) is studied. First, an experimental investigation is conducted to evaluate the effect of VO-notches on fracture behavior. To this end, VO-notched samples of PMMA are made and exposed to pure opening mode loading, pure tearing mode loading, and some combinations of these two loading types. As part of this study, samples with end-hole radii of 1, 2, and 4 mm are prepared to determine the effect of the notch end-hole size on the fracture resistance. Second, two well-known stress-based criteria, namely the maximum tangential stress (MTS) criterion and the mean stress (MS) criterion, are developed for VO-shaped notches subjected to mixed-mode I/III loading, also determining the associated fracture limit curves. A comparison between the theoretical and the experimental critical conditions indicates that the resulting VO-MTS and VO-MS criteria predict the fracture resistance of VO-notched samples with about 92% and 90% accuracy, respectively, confirming their capacity to estimate fracture conditions.
15
Johnson, Joseph, and Daniel Kujawski. "Impact of Notches on Additively Manufactured Inconel 718 Tensile Performance." Materials 16, no. 20 (2023): 6740. http://dx.doi.org/10.3390/ma16206740.
Full textAbstract:
This study was completed in effort to characterize the notch sensitivity of additively manufactured (AM) Inconel 718 produced by laser powder bed fusion (L-PBF). Three different root radii on V-notched test specimens and smooth specimens were evaluated under tensile conditions for specimens built in vertical and horizontal orientations. Both the total axial strain and localized notch diametral strain were measured. Finite element analysis (FEA) was completed on each specimen geometry to confirm the actual strain measurements near the notch. Test results showed the tensile strength of the notched specimens were larger than the tensile strength values of the smooth specimens. These tensile results equate to a notch-sensitivity ratio (NSR) greater than one, indicating that the L-PBF Inconel 718 material is a notch-strengthened material. It is suspected that the notch strengthening is a result of increased triaxial stress produced near the notch tip causing added material constraints, resulting in higher strength values for the notched specimens. Fractography analysis was completed on the various fracture surfaces and identified a dominate ductile failure mode within all of the specimens; however, the amount of ductility reduced with smaller notch root radii. While this study provides the initial notch responses of the L-PBF Inconel 718, further research must be completed in regard to the impact of notches on more complex loading behaviors, such as fatigue and stress-rupture conditions.
16
Sun, Jian, Lei Wu, and Chengqi Sun. "Effects of Notches and Defects on Dwell Fatigue Mechanism and Fatigue Life of Ti-6Al-4V ELI Alloy Used in Deep-Sea Submersibles." Journal of Marine Science and Engineering 9, no. 8 (2021): 845. http://dx.doi.org/10.3390/jmse9080845.
Full textAbstract:
The notch (i.e., stress concentration) and defect are important factors influencing the conventional fatigue behavior of metallic materials. What is the influence of notches and defects on the dwell fatigue mechanism and fatigue life? In this paper, the effects of notches and defects on the dwell fatigue behavior of the Ti-6Al-4V ELI alloy used in deep-sea submersibles are investigated under the load control mode. It is shown that the dwell fatigue is insensitive to the defect size (190–438 μm) compared to the conventional fatigue. For notched specimens, they all present fatigue failure mode under dwell fatigue testing, and the dwell fatigue life is higher than that of the smooth specimen at the same local maximum stress. The dwell of the maximum stress has no influence on the fatigue life and failure mechanism for notched specimens. Moreover, the facet feature is observed in the crack initiation region for both the conventional and dwell fatigue of notched specimens. Electron backscatter diffraction observation indicates that the feature of the fine line markings on the facet in the image by scanning electron microscope is due to the steps on the fracture surface of the α grain.
17
Braun, Moritz, Claas Fischer, Jörg Baumgartner, Matthias Hecht, and Igor Varfolomeev. "Fatigue Crack Initiation and Propagation Relation of Notched Specimens with Welded Joint Characteristics." Metals 12, no. 4 (2022): 615. http://dx.doi.org/10.3390/met12040615.
Full textAbstract:
This study focuses on predicting the fatigue life of notched specimens with geometries and microstructure representative of welded joints. It employs 26 series of fatigue tests on welded and non-welded specimens containing notches located in different material zones, including the parent material, weld metal, and heat-affected zone. Overall, 351 test samples made of six structural steels are included in the present evaluation. For each individual specimen, the stress concentration factor, as well as the stress distribution in the notched section, was determined for subsequent fracture mechanics calculation. The latter is employed to estimate the fraction of fatigue life associated with crack propagation, starting from a small surface crack until fracture. It was shown that the total fatigue life can be realistically predicted by means of fracture mechanics calculations, whereas estimates of the fatigue life until macroscopic crack initiation are subject to numerous uncertainties. Furthermore, methods of statistical data analyses are applied to explore correlations between the S–N curves and the notch acuity characterized by the notch radius, opening angle, and the stress concentration factor. In particular, a strong correlation is observed between the notch acuity and the slope of the S–N curves.
18
Rahimi, AS, MR Ayatollahi, and AR Torabi. "Elastic–plastic damage prediction in notched epoxy resin specimens under mixed mode I/II loading using two virtual linear elastic failure criteria." International Journal of Damage Mechanics 29, no. 7 (2020): 1100–1116. http://dx.doi.org/10.1177/1056789520905345.
Full textAbstract:
Elastic–plastic damage of a ductile epoxy resin is investigated for the first time in the configuration of semicircular bend specimen weakened by U-shaped notches under mixed mode I/II loading conditions. U-notched specimens are prepared from the characterized epoxy material with different notch rotation angles and notch tip radii. Load-carrying capacities of the U-notched specimens are experimentally obtained by performing fracture tests under various combinations of mode I and mode II loading. The reformulated Equivalent Material Concept is employed for the polymeric material in conjunction with the maximum tangential stress and mean stress criteria to provide the theoretical predictions without any necessity for elastic–plastic analyses of their damage. Scanning electron microscopy micrographs are also taken from the fracture surfaces and utilized for realizing the micromechanical processes of damage in the tested specimens. A very good consistency is found between the experimental results and the predictions of the combined Equivalent Material Concept-maximum tangential stress criterion, as well as those of the Equivalent Material Concept-mean stress criterion.
19
Duan, Kai, and Xiaozhi Hu. "Specimen boundary induced size effect on quasi‐brittle fracture." Strength, Fracture and Complexity: An International Journal 2, no. 2 (2004): 47–68. https://doi.org/10.3233/sfc-2004-030.
Full textAbstract:
A simple asymptotic analysis dealing with the influence of specimen boundaries on quasi‐brittle fracture of brittle heterogenous materials is presented. The influence of crack‐length/specimen‐size ratio (α‐ratio) on fracture behaviour of finite‐sized specimens has been quantitatively determined by the asymptotic boundary effect model. Different to the common size effect study relying on two scaling parameters that can only be determined by curve‐fitting to experimental results, the present boundary effect model is able to predict the quasi‐brittle fracture behaviour using two fundamental material properties: the tensile strength ft and fracture toughness KIC. ft and KIC can be determined separately following the standard strength and fracture toughness tests, or estimated from the available data in the literature for most commonly‐used materials. Alternatively, ft and KIC can be determined indirectly from quasi‐brittle fracture results using the boundary effect model so that the stringent tensile and fracture toughness tests can be replaced by the simple quasi‐brittle fracture tests. The boundary effect model shows the two scaling parameters used in the size effect study are α‐ratio dependent, and can only be taken as experimental constants for geometrically similar specimens of one single α‐ratio. Furthermore, un‐notched specimens containing small natural flaws have also been considered by the boundary effect model through linking the micro‐flaws to equivalent shallow notches with a near zero α‐ratio. As a result, both notched and un‐notched specimens can be analysed by the same boundary effect relationship.
20
Kidane, Addis. "On the Failure and Fracture of Polymer Foam Containing Discontinuities." ISRN Materials Science 2013 (September 10, 2013): 1–9. http://dx.doi.org/10.1155/2013/408596.
Full textAbstract:
An experimental study is performed to investigate the tensile failure and fracture behavior of polymer foam containing discontinuities. PVC corecell foam, series A800 and A1200 is used for the investigation. Unnotched dog-bone specimen and specimens with center hole and edge cracks are tested under uniaxial tensile loading. Series of experiments are conducted at different defect size to width ratios, and the effect of the defect size on the net-section tensile strength of the foam is investigated. A fracture study is also conducted, and the effect of density and loading rate on the fracture behavior of foam is investigated. A minimal notch-strengthening effect is observed in specimens with center hole, and a notch-weakening effect is observed in specimen with edge notches. Furthermore, the fracture toughness increases with the increase in the foam density and decreases with the increase in loading rate.
21
Cao, Shuai, Yun Chao Gu, Jun Hui Meng, and Ming Yun Lv. "Different Shape Notches Effects on Tearing Del-Zone for Stratospheric Airship Envelope Material." Advanced Materials Research 1049-1050 (October 2014): 77–80. http://dx.doi.org/10.4028/www.scientific.net/amr.1049-1050.77.
Full textAbstract:
Stratosphere airship envelope material is composed of multilayer laminated film material reinforced by fiber. As the same as other film material, it occurs del-zone in the course of crack tearing propagation, which is significant for envelope material mechanic studies. Many researched unlined its application, not it’s forming factors. The paper focus on crack or notch shape effects on the del-zone. Six groups test including specimen with no crack, central crack, square notch, diamond notch, circle notch, and rectangle notch are carried on under the stretching instrument to find the different del-zone phenomenon and get displacement-load curve. Combined with theory, the paper try to explain the del-zone differences for specimens and explore the shape notched sensitivity to specimen. The results shows that different specimen have differences on del-zone, further affecting the specimen module and fracture strength. In turn, it manifests that to some extent, the size del-zone decides fracture stress value, providing advice for airship envelope designing.
22
Albinmousa, Jafar, Jihad AlSadah, Muhammad A. Hawwa, and Hussain M. Al-Qahtani. "Estimation of Mode I Fracture of U-Notched Polycarbonate Specimens Using the Equivalent Material Concept and Strain Energy Density." Applied Sciences 11, no. 8 (2021): 3370. http://dx.doi.org/10.3390/app11083370.
Full textAbstract:
Polycarbonate (PC) has a wide range of applications in the electronic, transportation, and biomedical industries. In addition, investigation on the applicability to use PC in superstrate photovoltaic modules is ongoing research. In this paper, PC is envisioned to be used as a material for structural components in renewable energy systems. Usually, structural components have geometrical irregularities, i.e., notches, and are subjected to severe mechanical loading. Therefore, the structural integrity of these components shall consider fracture analysis on notched specimens. In this paper, rectangular PC specimens were machined with straight U-notches having different radii and depths. Eight different notch radii with a depth of 6.0 mm were tested. In addition, three notch depths with a radius of 3.5 mm were considered. Quasi-static fracture tests were performed under displacement-controlled loading with a speed of 5 mm/min. Digital image correlation technique was used to capture the strain fields for un-notched and notched specimens. It was assumed that fracture occurs at the onset of necking. The equivalent material concept (EMC) along with the strain energy density criterion (SED) were employed to estimate the fracture load. The EMC-SED combination is shown to be an effective and practical tool for estimating the fracture load of U-notched PC specimens.
23
Derpeński, Łukasz. "Ductile Fracture Behavior of Notched Aluminum Alloy Specimens under Complex Non-Proportional Load." Materials 12, no. 10 (2019): 1598. http://dx.doi.org/10.3390/ma12101598.
Full textAbstract:
The paper presents an experimental investigation of the ductile fracture of specimens with different circumferential notches. Specimens made from ENAW_2024-T351 aluminum alloy were subjected to non-proportional tension–torsion loading. The tests were carried out on an MTS testing machine coupled with the ARAMIS 3D 4M vision measuring system, enabling simultaneous non-contact tracking of the elongation and torsional angle of the measurement base. Depending on the assumed notch radius and the non-proportionate load scheme, the critical tensile force and torsional moments that caused the fracture initiation of the specimen were determined. A significant effect of load configurations and notch radius on the shape of the fracture surface as well as the fracture mechanisms causing the failure of specimens was demonstrated. The equation describing the configuration of critical loads for specimens with different notch radii was applied.
24
Kawai, Masamichi, and Akihiro Tanaka. "Effects of Stacking Sequence on Notched Strengths of Cross-Ply CFRP Laminates and Analysis Using a Cohesive Zone Model." Key Engineering Materials 340-341 (June 2007): 155–60. http://dx.doi.org/10.4028/www.scientific.net/kem.340-341.155.
Full textAbstract:
Effects of the thickness of plies of the same orientation on the notched strength of symmetric cross-ply CFRP laminates are examined. Three kinds of symmetric cross-ply CFRP laminates with the same total number of plies and the different number and sequence of adjacent laminae of the same orientation are used. Notch sensitivity of those laminates is evaluated for different shapes of notches: double-edge notches (DEN) and a center open hole (CH). Validity of an analytical cohesive zone model (CZM) is evaluated by comparing with experimental results on the three kinds of cross-ply laminates with a center hole. It is clearly observed that the tensile fracture strengths of the DEN and CH specimens significantly reduce as the notch size increases. The sensitivity to notches is highest in the case of alternating cross-ply configuration. The results of this study suggest that additional energy dissipation due to damage around notches should appropriately be considered to estimate the effective fracture toughness used in CZM calculations, especially for a class of cross-ply laminates with lower notch sensitivity.
25
M R, Sunil Kumar, Eva Schmidova, Pavel Konopík, Daniel Melzer, Fatih Bozkurt, and Neelakantha V Londe. "Fracture Toughness Analysis of Automotive-Grade Dual-Phase Steel Using Essential Work of Fracture (EWF) Method." Metals 10, no. 8 (2020): 1019. http://dx.doi.org/10.3390/met10081019.
Full textAbstract:
Fracture toughness determination of dual-phase DP450 steel using the essential work of fracture (EWF) methodology is the major focus of this research work. The EWF method is used for the determination of fracture toughness of thin sheets in a plane stress dominant condition. The EWF method is discussed in detail with the help of DP450 steel experimental results. Double edge notched tension (DENT) specimens with fatigue pre-crack and without fatigue crack (notched) have been used for testing. Specific essential work of fracture (we), crack tip opening displacement (δce) and crack tip opening angle (ψe) parameters were used for the comparative analysis. High-intensity laser beam cutting technology was used for the preparation of notches. Fracture toughness values of fatigue pre-cracked and notched samples were compared. The effect of notch tip radius and fatigue crack on the fracture toughness values were analysed. Digital image correlation (DIC) technology was used for the identification of local strain distribution and validation of the methodology. Fractured surfaces were examined by a scanning electron microscope (SEM) to analyse the fracture morphology and stress state.
26
Murakami, Tetsuya, Hiroyuki Toda, and Toshiro Kobayashi. "Effects of Temperature and Loading Rate on Fracture Toughness." Key Engineering Materials 297-300 (November 2005): 2397–402. http://dx.doi.org/10.4028/www.scientific.net/kem.297-300.2397.
Full textAbstract:
It is known that fracture toughness value is affected by test temperature, specimen thickness and loading rate. In the present study, specimen size and test temperature are varied widely with the obtained data then being analyzed using rate parameter. Additionally, the fracture toughness values are obtained using round bar-type specimen with a circular notch. This result is compared with the result of the CT specimens, and the advantage of using the round bar-type specimen with a circular notch to modify specimen size requirement is discussed. Sample material used is HT780 high tensile strength steel. The test specimens were 1T, 2T and 4T-CT that are described in ASTM E399. Notched round bar-type specimen with a diameter of 15mm and notch root radius of 0.25mm is also used. The test temperature is varied from a low temperature to room temperature, and loading rate is varied about the 1T-CT specimen and the notched round bar-type specimen between static and 1000mm/sec. The test temperature and the loading rate dependency of the fracture toughness values were arranged by the rate parameter. The fracture toughness value has decreased with the decrease in test temperature and with the increase in specimen thickness and loading rate. The fracture toughness value obtained from the notched round bar-type specimen indicated a value close to 2T-CT specimen. It is shown that valid fracture toughness value can be obtained with a small test specimen by the notched round bar-type specimen. The test temperature and the loading rate dependency of the fracture toughness values can be successfully arranged by the rate parameter that can express both temperature and strain rate dependencies. Feasibility of using round bar-type specimen to obtain valid fracture toughness values with less specimen mass was demonstrated.
27
Zhang, Sai Jun, Yan Chun Lu, Zhao Hui Shen, and Chi Zhou. "The Effect of Various Notches on the Prediction of the Ductile Fracture for SUS304 Sheets." Key Engineering Materials 794 (February 2019): 36–41. http://dx.doi.org/10.4028/www.scientific.net/kem.794.36.
Full textAbstract:
In this study, the Drucker yield function and S-shaped strain hardening model are employed to describe the yielding and hardening behaviors of SUS304 respectively. An uncoupled ductile fracture criterion is calibrated and then utilized to construct the fracture locus of SUS304. To explore the effect of various notches on the prediction of ductile fracture, the constitutive models and ductile fracture criterion are then introduced into the ABAQUS/Explicit code to predict the onset of ductile fracture of various notched specimens. The comparison demonstrates that the ductile fracture criterion captures the fracture strains for all specimens with different notch radius accurately and the finite element models predict the strain distribution, strain evolution and load-stroke curves with good agreement for specimens with large notch radius compared with the experimental results.
28
Makabe, Chobin, Takuya Nakayama, Masaki Fujikawa, Kazuo Arakawa, and Ding Ding Chen. "Effect of Specimen Thickness on Fatigue Limit in Carbon Composites." Advanced Materials Research 1110 (June 2015): 13–18. http://dx.doi.org/10.4028/www.scientific.net/amr.1110.13.
Full textAbstract:
The fracture behavior and fatigue limit in notched specimens of C/C composites were investigated. Also, the effect of specimen thickness on fatigue limit was discussed. Two plates of different thicknesses of plates of C/C composites using fine-woven carbon fiber laminates with α=0°/90° direction were used for testing. α is the angle between the carbon fiber direction and specimen axis. The crack growth behavior and failure mechanism of specimens are derived from the shear damage in the fiber bundle and matrix. Slits of several sizes were cut on both sides of a test section and different geometries of the specimens were prepared. Specimens with slits and blunt-notches were used to compare the fatigue strength. The fatigue limit is related to the method of making the plate of carbon composites. Large sizes of voids are observed in the case of specimens of thinner thickness. The fatigue limit was related to the void fraction, and thinner specimens showed a lower fatigue limit.
29
Gong, Shuang, Zhen Wang, Lei Zhou, and Wen Wang. "Experimental Investigation on the Tensile and Fracture Properties of Burst-Prone Coal under Quasistatic Condition." Shock and Vibration 2021 (February 26, 2021): 1–13. http://dx.doi.org/10.1155/2021/5593376.
Full textAbstract:
To study the tensile and fracture properties of the specimen under the quasistatic loading, the Brazilian disc splitting method and the notched semicircular bend (NSCB) method were used to test the tensile properties of coal specimens, and the fracture properties of NSCB specimens with different notch depths were tested and analyzed. The applicability of plane strain fracture toughness KIC and J-integral fracture toughness in evaluating the fracture properties of coal specimens was discussed. The influence of notch depth on the fracture toughness measurement of the NSCB specimen was studied. Combined with the surface strain monitoring of specimens during loading and the industrial CT scanning image of damaged specimens, the deformation characteristics of coal specimen under loads and the distribution law of crack after failure were analyzed. The results show that the NSCB test is suitable for measuring the tensile strength of a coal specimen; when the dimensionless notch depth is β = 0.28, the dispersion of plane strain fracture toughness KIC of the NSCB specimen is the smallest. Besides, the plane strain fracture toughness of coal is obviously affected by the notch depth and dimensionless stress intensity factor. The J-integral fracture toughness can be used to effectively evaluate the fracture performance of specimens.
30
Šodan, Matej, Vladimir Divić, Noémi Friedman, and Mijo Nikolić. "Investigating Bayesian Parameter Identification Using Non-Standard Laboratory Specimens." Applied Sciences 15, no. 11 (2025): 6194. https://doi.org/10.3390/app15116194.
Full textAbstract:
This work investigates the applicability of Bayesian inverse analysis for identifying parameters from non-standard aluminum specimens with notches that induce stress concentrations. Unlike conventional standardized specimens, the notched samples used in this work are typically unsuitable for direct parameter extraction due to geometric irregularities and size effects. The experimental procedure involved tensile tests conducted using a universal testing machine, with deformation data collected via LVDT sensors and optical measurements with digital image correlation. The numerical simulations were performed using a quadrilateral finite element model with embedded strong discontinuities to capture the complete material response, including elastic, plastic, and fracture behavior. The proposed identification procedure successfully provided reliable posterior parameter estimates on aluminum rectangular and single-notch specimens. Furthermore, the identified parameters were validated on a double-notch specimen made of the same material. The results highlight the importance of parameter interpretation and show that the Bayesian framework can reliably identify key material and model-dependent parameters from non-standard specimens while accounting for uncertainty in both measurements and model formulation.
31
Matache, Gheorghe, Alexandru Paraschiv, and Mihaela Raluca Condruz. "Tensile Notch Sensitivity of Additively Manufactured IN 625 Superalloy." Materials 13, no. 21 (2020): 4859. http://dx.doi.org/10.3390/ma13214859.
Full textAbstract:
The notch sensitivity of additively manufactured IN 625 superalloy produces by laser powder bed fusion (LPBF) has been investigated by tensile testing of cylindrical test pieces. Smooth and V-notched test pieces with four different radii were tested both in as-built state and after a stress relief heat treatment for 1 h at 900 °C. Regardless of the notch root radius, the investigated alloy exhibits notch strength ratios higher than unity in both as-built and in stress-relieved states, showing that the additive manufactured IN 625 alloy is not prone to brittleness induced by the presence of V-notches. Higher values of notch strength ratios were recorded for the as-built material as a result of the higher internal stress level induced by the manufacturing process. Due to the higher triaxiality of stresses induced by notches, for both as-built and stress-relieved states, the proof strength of the notched test pieces is even higher than the tensile strength of the smooth test pieces tested in the same conditions. SEM fractographic analysis revealed a mixed mode of ductile and brittle fracture morphology of the V-notched specimens regardless the notch root radius. A more dominant ductile mode of fracture was encountered for stress-relieved test pieces than in the case of the as-built state. However, future research is needed to better understand the influence of notches on additive manufactured IN 625 alloy behaviour under more complex stresses.
32
Panin, S. V., P. O. Maruschak, I. V. Vlasov, D. D. Moiseenko, F. Berto, and A. Vinogradov. "Effect of Temperature-Force Factors and Concentrator Shape on Impact Fracture Mechanisms of 17Mn1Si Steel." Advances in Materials Science and Engineering 2017 (2017): 1–12. http://dx.doi.org/10.1155/2017/9867217.
Full textAbstract:
The influence of the notch shape on the impact fracture of 17Mn1Si steel is investigated at different temperatures with the focus placed on the low-temperature behavior. An approach towards fracture characterization has been suggested based on the description of elastic-plastic deformation of impact loaded specimens on the stage of crack initiation and growth at ambient and lower temperatures. The analysis of the impact loading diagrams and fracture energy values for the pipe steel 17Mn1Si revealed the fracture mechanisms depending on the notch shape. It was found that the testing temperature reduction played a decisive role in plastic strain localization followed by dynamic fracture of the specimens with differently shaped notches. A classification of fracture macro- and microscopic mechanisms for differently notched specimens tested at different temperatures was proposed which enabled a self-consistent interpretation of impact test results.
33
Cicero, Sergio, Victor Martínez-Mata, Alejandro Alonso-Estebanez, Laura Castanon-Jano, and Borja Arroyo. "Analysis of Notch Effect in 3D-Printed ABS Fracture Specimens Containing U-Notches." Materials 13, no. 21 (2020): 4716. http://dx.doi.org/10.3390/ma13214716.
Full textAbstract:
In this paper a fracture assessment in additive manufactured acrylonitrile butadiene styrene (ABS) fracture specimens containing U-notches is performed. We performed 33 fracture tests and 9 tensile tests, combining five different notch radii (0 mm, 0.25 mm, 0.50 mm, 1 mm and 2 mm) and three different raster orientations: 0/90, 30/−60 and 45/−45. The theory of critical distances (TCD) was then used in the analysis of fracture test results, obtaining additional validation of this theoretical framework. Different versions of TCD provided suitable results contrasting with the experimental tests performed. Moreover, the fracture mechanisms were evaluated using scanning electron microscopy in order to establish relationships with the behaviour observed. It was demonstrated that 3D-printed ABS material presents a clear notch effect, and also that the TCD, through both the point method and the line method, captured the physics of the notch effect in 3D-printed ABS. Finally, it was observed that the change in the fracture mechanisms when introducing a finite notch radius was limited to a narrow band behind the original defect, which appeared in cracked specimens but not in notched specimens.
34
Samadian, Kaveh, Stijn Hertelé, and Wim De Waele. "A strain-based approach to study interaction between non-coplanar through-thickness edge notches." Journal of Strain Analysis for Engineering Design 53, no. 8 (2018): 687–98. http://dx.doi.org/10.1177/0309324718778440.
Full textAbstract:
Structural integrity assessment procedures to assess the effect of interaction between multiple adjacent flaws normally consist of two stages. First, alignment rules categorize non-coplanar flaws as aligned or non-aligned. Second, combination rules classify aligned flaws as interacting or non-interacting. Although these criteria are applied to different failure modes like brittle fracture, elastic–plastic fracture and plastic collapse, most of them were developed based on linear elastic fracture mechanics for the sake of simplicity. However, there are very limited references available for the technical background of these criteria. This lack of justifying backgrounds becomes more critical when applying these procedures to any other failure modes other than brittle fracture. This article studies the interaction between non-coplanar edge notches in scenarios of large deformation. Hereto, strain patterns are studied through full-field deformation measurements utilizing both experimental and numerical tools. Digital image correlation is used to measure strain during experiments and to verify the finite element analyses. The results show that in addition to the crack driving force, which represents a local response of notches, the global strain distribution within the specimen in terms of strain patterns can be used to probe the interaction between non-coplanar flaws. The authors suggest a novel criterion based on the trajectory of maximum equivalent strain to distinguish between aligned and non-aligned flaws. This study is based on double-edge notched tension specimens and gives a fundamental insight into flaw interaction in failure modes other than brittle fracture.
35
Yoo, Sang Hyup, Ki-Chae Chung, Hee-Beom Moon, Kyung Hoon Lee, and Kyung-Tae Park. "Notched Tensile Fracture of a Fe-15Mn-0.6C-2Al Twinning Induced Plasticity Steel at Room Temperature." Korean Journal of Metals and Materials 62, no. 5 (2024): 325–33. http://dx.doi.org/10.3365/kjmm.2024.62.5.325.
Full textAbstract:
The tensile fracture behavior of an Al-bearing TWIP steel was investigated by conducting a series of tensile tests on smooth and notched specimens with different notch geometries, focusing on the effects of evolution of the stress triaxiality and the effective strain during deformation. The flow curve and digital image correlation (DIC) analysis evidenced suppression of dynamic strain aging due to Al addition, and therefore, the effects of local inhomogeneous deformation associated with Portevin-Le Chatelier (PLC) band on fracture could be excluded. The smooth specimen fractured with negligible necking despite the absence of PLC bands. As a result, the effective strain was uniform through the gage section and the stress triaxiality (<i>η</i>) of ~0.33 was nearly unchanged over the entire cross-section up to the maximum load. This led to the fracture surface of the smooth specimen being entirely covered with fine equiaxed dimples. For notched specimens, the fracture strain was drastically reduced with decreasing notch radius, indicating the high notch susceptibility of the steel. The effective strain of the notched specimens was the highest at the edge of the notch root, regardless of the notch radius, so cracks first developed at the surface of the notch root. Although the <i>η</i> at the center of the notched specimens (0.40~0.48 depending on the notch radius) was higher than that of the smooth one, the center of the fracture surface of all notched specimens exhibited dimple features that were very similar to the smooth one, even in size. In contrast, in spite of the same <i>η</i> of ~0.33, fractography at the edge of the notched specimens revealed a fracture mode transition from dimple fracture to void sheet fracture to quasi-cleavage fracture as the notch radius decreased. The present results were rationalized in terms of the local evolution of stress triaxiality and effective strain during deformation, which were analyzed using the finite elemental method and DIC technique. It can be said that the fracture mode of TWIP steel, showing limited necking, was more influenced by the distribution and/or gradient of stress traiaxiality and effective strain rather than their local absolute values - that is, the severer their gradient is, the easier the quasi-cleavage fracture occurs.
36
Wei, Y., S. J. DeFranco, and J. P. Dempsey. "Crack-fabrication techniques and their effects on the fracture toughness and CTOD for fresh-water columnar ice." Journal of Glaciology 37, no. 126 (1991): 270–80. http://dx.doi.org/10.1017/s0022143000007280.
Full textAbstract:
Abstract The effects of notch acuity (crack-tip sharpness) on the fracture toughness of S2 ice were investigated using six groups of single-edge-notched-bend (SENB) specimens with different crack (or notch) root radii fabricated by six different methods. The mean value and standard deviations of the apparent fracture-toughness values K Q of the specimens with blunt notches were significantly higher than those of the specimens with sharp cracks. The results presented in a plot of fracture toughness versus , where p is the crack-tip radius, provide an estimate of the required notch acuity for fracture-toughness testing. The microstructural features in the immediate vicinity of the crack tip and the crack-tip geometry govern the magnitude of the apparent fracture toughness of the ice. The crack-tip-opening-displacement (CTOD) measured in this study indicates the existence of microplastic deformation in the vicinity of the crack tip at the initiation of unstable fracture.
37
Wei, Y., S. J. DeFranco, and J. P. Dempsey. "Crack-fabrication techniques and their effects on the fracture toughness and CTOD for fresh-water columnar ice." Journal of Glaciology 37, no. 126 (1991): 270–80. http://dx.doi.org/10.3189/s0022143000007280.
Full textAbstract:
AbstractThe effects of notch acuity (crack-tip sharpness) on the fracture toughness of S2 ice were investigated using six groups of single-edge-notched-bend (SENB) specimens with different crack (or notch) root radii fabricated by six different methods. The mean value and standard deviations of the apparent fracture-toughness values KQ of the specimens with blunt notches were significantly higher than those of the specimens with sharp cracks. The results presented in a plot of fracture toughness versus , where p is the crack-tip radius, provide an estimate of the required notch acuity for fracture-toughness testing. The microstructural features in the immediate vicinity of the crack tip and the crack-tip geometry govern the magnitude of the apparent fracture toughness of the ice. The crack-tip-opening-displacement (CTOD) measured in this study indicates the existence of microplastic deformation in the vicinity of the crack tip at the initiation of unstable fracture.
38
Suzuki, Akira, Akira Tanji, Zenjiro Yajima, Yukio Hirose, and Keisuke Tanaka. "X-Ray Diffraction Study of Fracture Surface Made by Fracture Toughness Tests of Blunt Notched CT Specimen of Aluminum Alloy." Advances in X-ray Analysis 30 (1986): 537–44. http://dx.doi.org/10.1154/s0376030800021704.
Full textAbstract:
X-ray fractography is a new method utilizing the X-ray diffraction technique to observe the fracture surface for the analysis of the micro-mechanisms and mechanics of fracture.In the present paper, X-ray fractography is applied to fracture surfaces of high strength aluminum alloy (JIS 7075-T6). The fracture toughness tests were conducted by using compact tension (CT) specimens with blunt notches and fatigue pre-cracks. The distribution of the residual stress near fracture surfaces was measured by the X-ray diffraction method. The effect of the notch radius on the fracture toughness value was discussed.
39
Kawamura, Noriyasu, Takashi Kawakami, Kikuo Kishimoto, Masaki Omiya, and Toshikazu Shibuya. "Strength Evaluation of Notch Structure for Semiconductor Encapsulant Resin." Journal of Electronic Packaging 124, no. 4 (2002): 323–27. http://dx.doi.org/10.1115/1.1501304.
Full textAbstract:
Plastic encapsulated semiconductor packages may crack at the corner regions of die pads or chips if internal delamination occurs at an elevated temperature during the reflow soldering process. Thus, the structural strength design around the notch structures, which will be formed in the encapsulant resin due to the delamination, is considered one of the most important issues. Especially, it becomes a more critical item of the package development in order to realize the reflow process with lead-free solder materials, whose melting points are higher than that of Sn63-Pb37. In this study, the fracture behavior of notched specimens, which were made of silica particulate-filled epoxy resins and modeled as the corner regions in actual packages, were studied with experimental and numerical analyses. First, the fracture tests of the notch structure of semiconductor encapsulant resin were carried out. A notch tip with several different radii was introduced to the specimen. The specimens were fractured by a three-point bending load. Second, the strength evaluation of the notch structure was carried out. The critical stress distribution σCr=max.[KIC/2πr1/2,σB] was used to determine the crack initiation at the notch tip. It is assumed that a fracture occurs when, at any point near the notch tip, the stress distribution exceeds the critical stress distribution determined by fracture toughness and bending strength. Three-dimensional finite element analysis was carried out to obtain the stress distributions around the notch tip in the specimen. The calculated stress distributions around the notch tip were compared with the critical stress distribution to estimate the fracture load of the specimen. Estimated fracture loads at room temperature and at high temperature were compared with the results of the fracture tests. It was confirmed that the predicted results based on the critical stress distribution corresponded very well with the experimental results. The validity of the criterion was confirmed by studying the fracture behavior of the notched specimens of actual silica particulate filled epoxy resins.
40
Ouhimmou, Siham, Abdelilah Hachim, and Houda Salmi. "Harmfulness Defect in Double-Notched Specimen of S533 Steel." International Journal of Engineering and Advanced Technology (IJEAT) 9, no. 4 (2020): 2287–92. https://doi.org/10.35940/ijeat.D7400.049420.
Full textAbstract:
The analytical solving of fracture mechanics equations remains insufficient for complex mechanisms, hence the use of finite element methods (FEM). The paper considered a test specimen with double S355 steel notches, stressed in tension, causing crack opening with two planes of symmetry. The refinement of the mesh is carried out at the bottom of the notch using the elements of Barsoum. The stress concentration coefficient and the crack propagation velocity are evaluated.
41
Majidi, HR, MR Ayatollahi, AR Torabi, and A. Zaheri. "Energy-based assessment of brittle fracture in VO-notched polymer specimens under combined compression-shear loading conditions." International Journal of Damage Mechanics 28, no. 5 (2018): 664–89. http://dx.doi.org/10.1177/1056789518780424.
Full textAbstract:
This research presents some experimental, numerical, and theoretical results on brittle fracture of disk-type test specimens weakened by V-notches with end-holes under mixed mode I/II loading with negative mode I contributions. First, 54 fracture tests are conducted on VO-notched Brazilian disk specimens made of the general-purpose polystyrene under mixed mode I/II loading with negative mode I contributions. Then, two energy-based brittle fracture criteria, namely the averaged strain energy density and averaged strain energy density based on the equivalent factor concept are proposed to predict the experimentally obtained fracture loads of the tested general-purpose polystyrene specimens. Additionally, the fracture initiation angles of the tested VO-notched Brazilian disk specimens are predicted by using averaged strain energy density criterion. The finite element analyses, as well as the experimental observations, show that although brittle fracture in the specimens under mixed mode I/II loading takes place from the applied load side of the notch border by local tensile stresses, the notch bisector line and the other sides of the notch border sustain compressive stresses. In fact, this phenomenon states the concept of mixed mode I/II loading with negative mode I contributions. Finally, it is shown that good agreement exists between the experimental results and the theoretical predictions of the two energy-based fracture criteria.
42
Zergot, Souad, Mustafa Moussaoui, and Brahim Elkhalil Hachi. "Evolution of Crack Propagation Rate in Notched Specimens Using XFEM Method under Bending Load Condition." Annales de Chimie - Science des Matériaux 46, no. 3 (2022): 155–62. http://dx.doi.org/10.18280/acsm.460307.
Full textAbstract:
The crack initiation and propagation often occur in structures subjected to fatigue loads and their privileged sites it is the geometric discontinuity in particular the notches. The geometric configuration of the notches always leads to disturbances of stress fields in the vicinity of the notch end as a consequence of the effects on the crack initiation site and on the crack rate. The present study is interested to the evolution of crack speed propagation in the notched specimens subjected to bending. The specimens chosen are made of PMMA material containing two opposite notches U or V that presented two different parameters, a radius for U-notch and angle for V-notch. The variations taken into account for the sharp notches (V-notch) going from the small angle to the large angle, which are 30°; 45°, 90°, and 140°, and for blunt notches (U-notch) the radius takes the different values 0.5, 1, 1.5, and 2 mm. The fracture brittle behavior adapted to this material led to predict the Fatigue crack growth using a modified form of Paris’s law with the equivalent stress intensity factor (ΔKeq) relying on extended finite element method (XFEM) in order to follow the interaction between the notch and the crack on one side and study the evolution of crack growth rate to another side. The variations, which brought to these parameters entailed an influence on the crack propagation speed, which was born at the end of notch of component as well as the variations of equivalent notch intensity stress factors (ΔKeq). The variations made to the parameters of notches have a huge influence on the crack propagation rate.
43
Nakai, Yoshikazu, Naoki Sei, and Bok Key Kim. "Notched Fatigue of Zr-Based Bulk Metallic Glass." Key Engineering Materials 345-346 (August 2007): 259–62. http://dx.doi.org/10.4028/www.scientific.net/kem.345-346.259.
Full textAbstract:
In the present study, fatigue tests of sharp-notched Zr-based bulk metallic glass (BGM), were conducted under fully reversed cyclic bending, and the fatigue crack initiation mechanisms were clarified by using AFM. The fracture surface was also observed to examine the crack propagation mechanism. The fatigue notch factor was 2.0, while the elastic stress concentration factor is 2.7. From the macroscopic observations of fractured specimen, either tension mode or shear mode fracture morphologies were observed. Either in smooth specimens or notched specimens, no prodigious sign of crack initiation were observed, i.e., fatigue cracks were initiated from shear bands those were formed just before the crack initiation.
44
Forquin, Pascal. "Influence of Free Water and Strain-Rate on the Shear Behaviour of Concrete." Applied Mechanics and Materials 82 (July 2011): 148–53. http://dx.doi.org/10.4028/www.scientific.net/amm.82.148.
Full textAbstract:
Shear fracture (mode II) may be observed in concrete structures when subjected to confined or impact loading. Among the different techniques developed to investigate the shear strength of geomaterials, figures the Punch-Through Shear test (PTS test). It consists of a short cylinder with two cylindrical notches made on the lower and upper surfaces. Shear fracture is produced in the ligament due to the displacement of the central zone beside the peripheral zone. An experimental setup has been developed in LEM3 laboratory to measure the shear strength of concrete under quasi-static and dynamic loading. A high-speed hydraulic press allowed reaching strain-rates up to few per second. Steel and aluminium alloy confining rings have been used to induce a confining pressure in the fractured zone. Furthermore, radial notches have been performed in the specimen in order to deduce the radial stress at the ligament surface from the contact pressure between the confining ring and the outer surface of the specimen. The experimental results have been used to discuss the influence of free water and strain-rate on the shear behaviour of concrete.
45
Kim, Jae Hoon, Duck Hoi Kim, Nam Su Rho, Young Shin Lee, Song Heo Koo, and Soon Il Moon. "An Evaluation of Fracture Toughness of Glass-Filled Ceramic Using Notched Specimen." Key Engineering Materials 326-328 (December 2006): 927–30. http://dx.doi.org/10.4028/www.scientific.net/kem.326-328.927.
Full textAbstract:
The objective of this study is to evaluate the mechanical properties of static, quasidynamic and dynamic fracture toughness of glass-filled ceramic as promising structural material for a dome port cover of a ramjet engine system. Static and quasi-dynamic tests were carried out using SEPB (Single Edge Pre-cracked Beam) specimens. Static and dynamic fracture toughness tests were also performed using ASTM and strain gage methods with SENB (Single Edge Notched Beam) specimens machined with various notch radii. The critical notch radius was evaluated. Below the critical notch radius, the static fracture toughness of the SENB specimen well agreed with that of the SEPB specimen.
46
Büyükkaya, Kenan, and Faruk Güner. "Determination of Static Fracture Toughness of Nettle Fibre (Urtica Dioica)/Polymethyl-methacrylate Composites Using Different Fracture Methods." Mechanics 26, no. 2 (2020): 95–102. http://dx.doi.org/10.5755/j01.mech.26.2.23308.
Full textAbstract:
In this study, the breaking behaviour of polymethylmethacrylate reinforced with nettle fibre was investigated experimentally. Single edge notched bending (SENB) and compact test(CT) specimens were produced to include notches in various ratios. The Mode I fracture behaviour of samples were determined utilizing static frac-ture toughness experiments such as the Three Point Bend-ing (TPB) and Compact Tensile tests. The fracture tough-ness (KIC) was investigated using the TPB Test (Compli-ance and Initial notch method), and Compact Tension test. The bending module and bending stresses were also determined. It was found that nettle-fibre reinforcement improves the bending strength of the composite by 60% and improves the fracture toughness more than two-fold.
47
Mora Santos, Carlos A., Orlando Susarrey Huerta, Vicente Flores Lara, Jorge Bedolla Hernández, and Maribel A. Mendoza Nuñez. "Failure Stress in Notched Paper Sheets." Key Engineering Materials 569-570 (July 2013): 417–24. http://dx.doi.org/10.4028/www.scientific.net/kem.569-570.417.
Full textAbstract:
In this work the crack initiation stress of notched specimens of filter paper is studied. The paper in the microstructure has a random array in their fibers while macroscopically it behaves anisotropically. The self-affine crack mechanics is used to study the size effect in the tensile behavior of this kind of paper under the presence of several conditions of geometrical notches. While in the traditional fracture mechanics the crack initiation stress is a material parameter when is reached a critical level at the crack tip, in the self-affine crack mechanics, depends moreover of the resulting tortuosity of the crack. Four geometrical arrangements in two sizes we considered: centered circular notch, centered lineal notch, sided circular notches and without notch at 10 and 300 mm width with a relation 2a/w = 0.25 under the same loading conditions. In this, the without notch specimens present the higher stress, all other notched specimens presented a similar crack initiation stress about 1 % of difference among them, and the crack growth is not affected by the geometry of notch. In spite of this difference, no one of the specimens reach the theoretical stress concentration of 3 such as predicted the classical stress theory.
48
Savaidis, G., A. Savaidis, O. Hertel, and M. Vormwald. "A Unified Fatigue Life Calculation Model for Notched Components Based on Elastic-Plastic Fracture Mechanics." Key Engineering Materials 348-349 (September 2007): 525–28. http://dx.doi.org/10.4028/www.scientific.net/kem.348-349.525.
Full textAbstract:
Based on Dankert’s et al. [1] initial model for the elastic-plastic evaluation of fatigue crack growth in sheets providing elliptical notches, a generalized procedure enabling an improved evaluation of the effective ranges of the crack driving force (i.e. the J-Integral) as well as the application to arbitrary notched components has been developed [2]. The present paper presents the basic topics of the calculation model as well as its verification using experimental results from notched specimens with various notch shapes subjected to cyclic loading with various load ratios.
49
Klusák, Jan, D. Kopp, and Tomáš Profant. "Bi-Material Notches under Various Normal-Shear Loading Modes." Key Engineering Materials 577-578 (September 2013): 361–64. http://dx.doi.org/10.4028/www.scientific.net/kem.577-578.361.
Full textAbstract:
In the range of linear elastic fracture mechanics, the critical loading assessment of structures made of two dissimilar materials is usually based on the assumptions of the prevailing normal mode of loading. However, in engineering practice there are cases of loading and failure close to the shear mode of loading. The aim of the work is to study the stress distribution in the vicinity of a bi-material notch subjected to a combination of normal and shear modes of loading. Then the stability criteria use knowledge of common fracture mechanics properties for normal I and shear II modes of loading. The assessment of crack initiation conditions is shown on a specimen with two different bi-material notches under loading of a varying direction.
50
Kou, L. Y., W. Y. Zhao, X. Y. Tuo, G. Wang, and C. R. Sun. "Effect of stress triaxiality on fracture failure of 6061 aluminium alloy." Journal of Mechanical Engineering and Sciences 14, no. 2 (2020): 6961–70. http://dx.doi.org/10.15282/jmes.14.2.2020.33.0545.
Full textAbstract:
The effect of stress triaxiality on mechanical properties of 6061 aluminium alloy extruded profiles with different specimens was studied. Macroscopic mechanical property of the various specimen was got through universal testing machine. At the same time, stress triaxiality of different specimens was obtained using the method of finite element simulation. And then the fracture strain of each specimen was outputted by DIC. Fracture modes of 6061 aluminium alloy with different stress triaxiality were studied by SEM. The results show that taking tensile samples as comparison, the cross-sectional area of some notched specimens decreases and the peak load increases. Among them, the minimum cross-sectional area of the R5 central hole specimen is 20% smaller than that of the tensile sample, and the peak load is 28% larger. The fracture strain of the alloy increased with the decrease of stress triaxiality. For the same notch specimens, along the path direction, stress triaxiality of R5 notch specimens, R5 Center-hole specimens and R20 Arc notched specimens increased 47%, 17.8%, 25% respectively. According to the analysis of fracture morphology, the main fracture of 6061 aluminium alloy was ductile fracture. When the stress triaxiality is large, the dimples are small and sparsely distributed, and when the stress triaxiality is small, the dimple is large and evenly distributed. Finally, the Johnson-Cook model material parameters of 6061 aluminum alloy are fitted based on the tensile test results of different shapes of specimens, which can accurately simulate the elastic-plastic deformation and fracture instability of 6061 aluminum alloy under different stress states.