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1
Parasuraman, Prabhuraj, Tushar Sonar, and Selvaraj Rajakumar. "Microstructure, tensile properties and fracture toughness of friction stir welded AA7075-T651 aluminium alloy joints." Materials Testing 64, no. 12 (2022): 1843–50. http://dx.doi.org/10.1515/mt-2022-0212.
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Abstract The main objective of this investigation is to study the microstructure, tensile properties and fracture toughness of friction stir welded (FSW) butt joints of 10 mm thick AA7075-T651 plates. The microstructural features of stir zone (SZ), thermos-mechanically affected zone (TMAZ), heat affected zone (HAZ) were analyzed using optical microscopy technique. The tensile properties were evaluated using smooth and notch tensile specimens and compared to base metal properties. The microhardness survey was done across the weld cross section and correlated to the failure of tensile specimens. Compact tension (CT) specimens were used to evaluate the fracture toughness of welded joints. The fractured tensile and CT specimens were analyzed using scanning electron microscopy (SEM). Results showed that the FSW AA7075-T651 specimens welded using axial load of 12 kN, tool rotation speed of 750 rpm and welding speed of 30 mm/min exhibited 412 MPa tensile strength and 9% elongation. It showed 88 and 89% of base metal strength elongation. The joints showed fracture toughness of 23 MPa m1/2 which is 80% of base metal fracture toughness. The superior tensile and fracture toughness properties of joints are mainly attributed to the evolution of finer grains in SZ due to the stirring action of FSW tool.
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Kubošová, Andrea, Miroslav Karlík, Petr Haušild, and J. Prahl. "Fracture Behaviour of Fe3Al and FeAl Type Iron Aluminides." Materials Science Forum 567-568 (December 2007): 349–52. http://dx.doi.org/10.4028/www.scientific.net/msf.567-568.349.
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Fracture behaviour of two intermetallic alloys based on FeAl and Fe3Al was studied. On the alloys Fe-40Al-1C (at%) and Fe-29.5Al-2.3Cr-0.63Zr-0.2C (at%) (FA06Z), a basic characterization, the fracture toughness tests and fractographic analysis were carried out. Tensile tests and fracture toughness tests were performed at 20, 200, 400 and 600°C. The fracture toughness values range from 26 MPa.m1/2 at 20°C to 42 MPa.m1/2 at 400°C. In addition, Jintegral dependence on a obtained by potential method was measured. The fractographic analysis showed that samples fractured at 20, 200 and 400°C in the tensile or fracture toughness tests exhibit transgranular cleavage fracture, while at 600°C the ductile dimple fracture predominates.
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He, Rui, Longfei Cheng, Yidi Gao, Hao Cui, Yulong Li, and Jianhu Liu. "Fracture toughness of fibre failure modes in laminated composites under dynamic loading." Journal of Physics: Conference Series 2891, no. 16 (2024): 162001. https://doi.org/10.1088/1742-6596/2891/16/162001.
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Abstract The fracture toughness regarding fibre tensile failure and fibre compression kinking was measured using compact tension and compact compression specimens on a uniaxial bi-directional electromagnetic Hopkinson bar system. During the dynamic tests, the strain/displacement fields were monitored using the digital image correlation technique with a high-speed camera. Digital and scanning electron microscopy were used to investigate the fracture faces of the tested specimens. The initial fracture toughness for fibre tensile failure under quasi-static and dynamic loading was 166 kJ/m2 and 113 kJ/m2, respectively. For fibre compression kinking, the initial fracture toughness was approximately 120 kJ/m2 for both loading conditions. Less fibre pull-out may be responsible for the decrease in fracture toughness for fibre tensile failure under dynamic loading. Whereas for fibre compression kinking failure, there was no significant difference in the fracture faces of the damaged specimens at different loading rates.
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Man, Ke, and Xiaoli Liu. "Dynamic Fracture Toughness and Dynamic Tensile Strength of the Rock from Different Depths of Beijing Datai Well." Advances in Civil Engineering 2018 (August 29, 2018): 1–8. http://dx.doi.org/10.1155/2018/2567438.
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From the standard test method suggested by ISRM and GB/T50266-2013, the uniaxial static tensile strength, dynamic tensile strength, and dynamic fracture toughness of the same basalt at different depths have been measured, respectively. It is observed that there may be an empirical relation between dynamic fracture toughness and dynamic tensile strength. The testing data show that both the dynamic fracture toughness and dynamic tensile strength increase with the loading rate and the dynamic tensile strength increases a little bit more quickly than the dynamic fracture toughness. With an increasing depth, the dynamic tensile strength has much more influence on the dynamic fracture toughness, as which it is much liable to bring out the unexpected catastrophes in the engineering projects, especially during the excavation at deep mining. From the rock failure mechanisms, it is pointed out that the essential reason of the rock failure is the microcrack unstable propagation. The crack processes growth, propagation, and coalescence are induced by tensile stress, not shear stress or compressive stress. The paper provides estimation of the dynamic fracture toughness from the dynamic tensile strength value, which can be measured more easily.
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Pokluda, Jaroslav, Ivo Dlouhý, Marta Kianicová, Jan Čupera, Jana Horníková, and Pavel Šandera. "Temperature Dependence of Fracture Characteristics of Variously Heat-Treated Grades of Ultra-High-Strength Steel: Experimental and Modelling." Materials 14, no. 19 (2021): 5875. http://dx.doi.org/10.3390/ma14195875.
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The temperature dependence of tensile characteristics and fracture toughness of the standardly heat-treated low-alloyed steel OCHN3MFA along with three additionally heat-treated grades was experimentally studied. In the temperature range of ⟨−196; 22⟩ °C, all the additional heat treatments transferred the standard steel from a high- to ultra-high strength levels even with improved tensile ductility characteristics. This could be explained by a reduction of the inclusion content, refinement of the martensitic blocks, ductile retained austenite content, and homogenization of the shape ratio of martensitic laths as revealed by metallographic, X-ray, and EBSD techniques. On the other hand, the values of the fracture toughness of all grades were found to be comparable in the whole temperature range as the cause of a high stress triaxiality in the pre-cracked Charpy V-notch samples. The values of the fracture toughness of the standard steel grade could be predicted well using the fracture model proposed by Pokluda et al. based on the tensile characteristics. Such a prediction failed in the case of additionally heat-treated grades due to the different temperature dependence of the fracture mechanisms occurring in the tensile and fracture-toughness tests. While the tensile samples fractured in a ductile-dimple mode at all temperatures, the fracture-toughness specimens exhibited a transition from the ductile to quasi-brittle fracture mode with decreasing temperature. This transition could be interpreted in terms of a transfer from the model proposed by Rice and Johnson to the model of Tvergaard and Hutchinson.
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Woo, Sung Choong. "Tensile Behavior and Fracture Toughness of Glass Fiber Reinforced Aluminum Laminates According to Fiber Layer Orientation." Key Engineering Materials 326-328 (December 2006): 1039–42. http://dx.doi.org/10.4028/www.scientific.net/kem.326-328.1039.
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The objective of this study is to investigate the tensile behavior and fracture toughness of glass fiber reinforced aluminum hybrid laminates (GFAL) in association with the fracture process using plain coupon and single-edge-notched specimens. The tensile properties of GFAL, such as elastic modulus and ultimate tensile strength, were clearly dependent on the fiber orientations. In particular, the superiority of GFAL0 in KIC and GIC was much more pronounced than that of monolithic Al 1050. However, a transverse crack parallel to the fiber orientation reduced the toughness of GFAL considerably. Microscopic observations of the fracture zone in the vicinity of the crack tip exhibited various modes of micro-fracture in the respective layers as well as fiber fractures and interface delamination between fiber composite and Al layers. Such a damage evolution in GFAL depending on the fiber layer orientation had strongly influence upon the tensile behavior and the toughness of GFAL.
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Dolatshahi, Alireza, and Hamed Molladavoodi. "PREDICTION OF ROCK TENSILE FRACTURE TOUGHNESS: HYBRID ANN-WOA MODEL APPROACH." Rudarsko-geološko-naftni zbornik 39, no. 3 (2024): 1–12. http://dx.doi.org/10.17794/rgn.2024.3.1.
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Various techniques are used in rock engineering to evaluate tensile fracture toughness, which is a critical parameter in assessing and designing stable rock structures. These methods typically involve laboratory investigations and statistical analysis. Nevertheless, artificial neural networks can also establish correlations among different data sets. Artificial intelligence approaches are becoming increasingly essential in all engineering fields, including the ones that study rock fracture mechanics. In this work, an artificial neural network with a hidden layer and eight neurons as well as a hybrid artificial neural network with a whale optimization algorithm were utilized to determine the tensile fracture toughness of rocks. In order to develop accurate models, this study has carefully selected four fundamental parameters to serve as inputs. These parameters include radius, thickness, crack length, and mean tensile strength of specimens. Also, 113 rock datasets were collected for models. The results show that utilization of the optimization algorithm enhances the precision in estimating the tensile fracture toughness of rocks. The R2 improved to 0.93 when the whale optimization algorithm was used. On the other hand, the correlation factor reached 0.81 when the whale optimization algorithm was not implemented.
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Mäkelä, Petri, and Christer Fellers. "An analytic procedure for determination of fracture toughness of paper materials." Nordic Pulp & Paper Research Journal 27, no. 2 (2012): 352–60. http://dx.doi.org/10.3183/npprj-2012-27-02-p352-360.
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Abstract The aim of the present work was to develop an analytic procedure for determination of the fracture toughness of paper materials based on laboratory material test data. Isotropic deformation theory of plasticity was used to model the tensile material behaviour of six different commercial paper grades. Closed-form analytic expressions for calibrating the material model based on tensile test data were developed. The analytically calibrated material model was shown to predict the non-linear tensile stress-strain behaviour of the investigated paper grades excellently. A closed-form analytic expression for determination of fracture toughness was developed based on the used material model and J-integral theory. The fracture toughness of the investigated paper grades was determined analytically based on laboratory fracture toughness test data. The suggested analytic procedure for determination of the fracture toughness was shown to be in excellent agreement with determinations of fracture toughness based on finite element analysis.
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Lee, Soo Hyun, Jink Wang Kim, Su Nam Kim, Sang Bong Cho, and Jon Do Yun. "Interfacial Fracture Toughness for Film on Substrate Determined by Indentation Method." Key Engineering Materials 345-346 (August 2007): 801–4. http://dx.doi.org/10.4028/www.scientific.net/kem.345-346.801.
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Indentation method was used to determine the interfacial fracture toughness of epoxy coating on aluminum substrate. Tensile testing followed by finite element analysis was also performed to determine the interface fracture toughness. Fracture toughness values determined by two methods were consistent, giving reliability to indentation method for interfacial fracture toughness measurement.
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Tschegg, Elmar K., and Subra Suresh. "Tensile Fracture Toughness Measurements in Ceramics." Journal of the American Ceramic Society 70, no. 3 (1987): C—41—C—43. http://dx.doi.org/10.1111/j.1151-2916.1987.tb04960.x.
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Liu, H., B. G. Falzon, G. Catalanotti, and W. Tan. "An experimental method to determine the intralaminar fracture toughness of high-strength carbon-fibre reinforced composite aerostructures." Aeronautical Journal 122, no. 1255 (2018): 1352–70. http://dx.doi.org/10.1017/aer.2018.78.
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ABSTRACTCarbon fibres with high tensile strength are being increasingly utilised in the manufacture of advanced composite aerostructures. A Modified Compact Tension (MCT) specimen is often deployed to measure the longitudinal intralaminar fracture toughness but a high tensile strength often leads to premature damage away from the crack tip. We present an approach whereby the MCT specimen is supported by external fixtures to prevent premature damage. In addition, we have developed a novel measurement technique, based on the fibre failure strain and C-scanning, to determine the crack length in the presence of surface sublaminate delamination which masks the crack tip location. A set of cross-ply specimens, with a ((90/0)s)4 layup, were manufactured from an IMS60/epoxy composite system Two different data reduction schemes, compliance calibration and the area method, are used to determine the fibre-dominated initiation and propagation intralaminar fracture toughness values. Propagation values of fracture toughness were measured at 774.9 ± 5.2% kJ/m2 and 768.5 ± 4.1% kJ/m2, when using the compliance calibration method and the area method, respectively. Scanning Electron Microscopy (SEM) is carried out on the fracture surface to obtain insight into the damage mechanism of high-tensile-strength fibre-reinforced unidirectional composites. The measured tensile fracture toughness value is used in a fully validated computational model to simulate the physical test.
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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.
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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.
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Shum, D., M. N. Bassim, and M. R. Bayoumi. "Dynamic tensile fracture toughness evaluation using compact tension specimens." International Journal of Fracture 29, no. 1 (1985): R3—R10. http://dx.doi.org/10.1007/bf00020677.
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Lu, Fang Yun, Xiao Feng Wang, Rong Chen, et al. "Comparison Investigation of Tensile Fracture Properties of Al Alloy at Different Dynamic Loadings." Key Engineering Materials 535-536 (January 2013): 156–59. http://dx.doi.org/10.4028/www.scientific.net/kem.535-536.156.
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Spall Strength, uniaxial tensile strength and fracture toughness, are three typical parameters describing the fracture properties of materials subjected to different loadings. Actually, these three macroscopically parameters are connected to the tensile fracture (Model I) properties, and many papers have been trying to find the intrinsic connection between each other. In this work, ZL205A aluminum is conducted by varies experiments: the spallation test loaded by a light gas gun, the dynamic uniaxial tensile test using the Split Hopkinson Tensile Bars (SHTB), and the dynamic fracture toughness obtained with a three point bending specimen loaded by Split Hopkinson Pressure Bars (SHPB). The three parameters are compared with the view of energy. The results show that the cavity expansion model is successfully used to set up a connection between spallation strength and dynamic uniaxial tensile strength of this material, while the energy release rate or the surface energy can give a good prediction of dynamic tensile strength and fracture toughness.
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Liang, Li, Pu Rong Jia, and Gui Qiong Jiao. "Interlaminar Fracture Toughness of Composite Laminate with Splicing Plies." Advanced Materials Research 194-196 (February 2011): 1697–702. http://dx.doi.org/10.4028/www.scientific.net/amr.194-196.1697.
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Delamination is one of the important damage modes in the fiber-reinforced composite laminates. The interlaminar fracture toughness is the key parameter in delamination failure analysis of composites. The stress analysis by a finite element modeling has shown that the shear stress is very large near the ply splicing area. So the delamination failure is mainly dependent on the mode II fracture toughness. A new way of loading in tensile testing is proposed for the measurement of mode II fracture toughness. Specific specimen with splicing plies has been designed and used for the experiment. Testing study on the carbon-fiber-reinforced laminate with ply splicing was performed. Steady crack propagation has been seen by the tensile testing of the specimen. Mode II fracture toughness GIIC of the laminate has been determined by the experiment data analysis. The experiment and numerical analysis shows that the tensile testing for the measurement of mode II interlaminar fracture toughness is feasible.
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Bozkurt, Fatih, and Eva Schmidová. "Fracture Toughness Evaluation of S355 Steel Using Circumferentially Notched Round Bars." Periodica Polytechnica Transportation Engineering 47, no. 2 (2018): 91–95. http://dx.doi.org/10.3311/pptr.11560.
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In engineering applications, steels are commonly used in various areas. The mechanical members are exposed to different loading conditions and this subject can be investigated in fracture mechanics. Fracture toughness (KIC) is the important material property for fracture mechanics. Determination of this properties is possible using a compact tension specimen, a single edge notched bend or three-point loaded bend specimen, which are standardized by different institutions. Researchers underline that these standardized methods are complex, the manufacturing process is difficult, they require special fixtures for loading during the experiment and the test procedures are time consuming. Alternative methods are always being sought by researchers. In this work, two different approaches are investigated for S355 steels. In the first method, a circumferentially cracked round bar was loaded in tensile mode and pulled till failure. Using suitable equations, fracture toughness can be calculated. In the second method, a circumferentially notched bar specimen without fatigue pre-cracking was loaded in a tensile machine. By means of fracture load values, fracture toughness was determined by the proposed equations. It can be stated that these two different approaches for calculating fracture toughness are simple, fast and economical.
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Yoon, Han Ki, D. H. Kim, Yi Hyun Park, Yu Sik Kong, and Akira Kohyama. "Evaluation Strength and Fracture Toughness of Reduced Activation Ferritic Steel (JLF-1) for Fusion Reactor." Key Engineering Materials 261-263 (April 2004): 147–52. http://dx.doi.org/10.4028/www.scientific.net/kem.261-263.147.
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Reduced activation ferritic (JLF-1) steel is one of the leading candidates for blanket/first-wall structures in D-T fusion reactors. In fusion applications, structural materials will suffer the effects of repeated temperature changes. Therefore, a database of tensile strength and fracture toughness are very important as the temperature is 400 ° C and it's TIG welded joint. In this paper, fracture toughness JIC and KIC) and tensile tests were carried out at room temperature (RT) and at elevated temperature (400 ° C). The tensile properties of the TIG welding joint of JLF-1 steel was also investigated. It was shown that the tensile strength and fracture toughness values of the JLF-1 steel are slightly decreased with as increase in temperature. The fracture toughness values of JLF-1 steel at room temperature and at 400°C show excellent JIC values of about 530 kJ/m2 and 340 kJ/m2, respectively.
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Bahmani, A., and S. Nemati. "Fracture resistance of railway ballast rock under tensile and tear loads." Engineering Solid Mechanics 9, no. 3 (2021): 271–80. http://dx.doi.org/10.5267/j.esm.2021.3.003.
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The influence of loading type on tensile and tearing fracture resistance of ballast rock was assessed using edge-notched diametrically compressed disc (ENDC) and edge-notched disc bend (ENDB) test geometries. The geometry of these two specimens was similar; however, their loading type (i.e., three-point bend and diametral compressive) was different affecting the geometry factors. The obtained pure tensile fracture toughness (KIc) using the ENDB test was higher than the ENDC test. In contrast to tensile fracture toughness, the pure tearing fracture toughness (KIIIc) in the ENDC test was higher than the ENDB fracture test. The obtained experimental data were explained in terms of crack propagation path, since two distinct trajectories were observed for both configurations under tearing deformation.
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Li, Lielie, Hekai Cao, Junfeng Guan, Shuanghua He, Lihua Niu, and Huaizhong Liu. "A Three-Parameter Weibull Distribution Method to Determine the Fracture Property of PMMA Bone Cement." Polymers 14, no. 17 (2022): 3589. http://dx.doi.org/10.3390/polym14173589.
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Poly (methyl methacrylate) (PMMA) bone cement is an excellent biological material for anchoring joint replacements. Tensile strength ft and fracture toughness KIC have a considerable impact on its application and service life. Considering the variability of PMMA bone cement, a three-parameter Weibull distribution method is suggested in the current study to evaluate its tensile strength and fracture toughness distribution. The coefficients of variation for tensile strength and fracture toughness were the minimum when the characteristic crack of PMMA bone cement was αch∗=8dav. Using the simple equation αch∗=8dav and fictitious crack length Δαfic=1.0dav, the mean value μ (= 43.23 MPa), minimum value ftmin (= 26.29 MPa), standard deviation σ (= 6.42 MPa) of tensile strength, and these values of fracture toughness (μ = 1.77 MPa⋅m1/2, KICmin = 1.02 MPa⋅m1/2, σ = 0.2644 MPa⋅m1/2) were determined simultaneously through experimental data from a wedge splitting test. Based on the statistical analysis, the prediction line between peak load Pmax and equivalent area Ae1Ae2 was obtained with 95% reliability. Nearly all experimental data are located within the scope of a 95% confidence interval. Furthermore, relationships were established between tensile strength, fracture toughness, and peak load Pmax. Consequently, it was revealed that peak load might be used to easily obtain PMMA bone cement fracture characteristics. Finally, the critical geometric dimension value of the PMMA bone cement sample with a linear elastic fracture was estimated.
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Alsaadi, Mohamad, and Ahmet Erkliğ. "Effect of sewage sludge ash filler on mode I and mode II interlaminar fracture toughness of S-glass/epoxy composites." Journal of Polymer Science and Engineering 5, no. 1 (2022): 431. https://doi.org/10.24294/jpse.v5i1.431.
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In this study, the influence of sewage sludge ash (SSA) waste particle contents on the mechanical properties and interlaminar fracture toughness for mode I and mode II delamination of S-glass fiber-reinforced epoxy composites was investigated. Composite laminate specimens for tensile, flexural double-cantilever beam (DCB), and end-notched fracture (ENF) tests were prepared and tested according to ASTM standards with 5, 10, 15, and 20 wt% SSA-filled S-glass/epoxy composites. Property improvement reasons were explained based on optical and scanning electron microscopy. The highest improvement in tensile and flexural strength was obtained with a 10 wt% content of SSA. The highest mode I and mode II interlaminar fracture toughness’s were obtained with 15 wt% content of SSA. The mode I and mode II interlaminar fracture toughness improved by 33% and 63.6%, respectively, compared to the composite without SSA.
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Zhang, Bo Ming, and Yu Fen Wu. "Experiment Research for Fracture Toughness of PAN-Based Carbon Fibers." Key Engineering Materials 462-463 (January 2011): 1361–66. http://dx.doi.org/10.4028/www.scientific.net/kem.462-463.1361.
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For the sake of the carbon filaments’ fracture toughness, using the focused ion beam (FIB) to etch the carbon fibers and got different tensile strength, and all specimens were stretched on an Instron-type filaments testing machine and got the samples’ tensile strength, The crack-to-mirror size ratio was assumed as a constant, In virtue of Griffith fracture theory, Fracture toughness (KΙC) of representative high-strength type PAN (polyacrylonitrile)-based carbon fibers, Torayca T300 and T800, were estimated to be 1MPam1/2 from the tensile strength vs. fracture mirror size relation.
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Shao, Yong Zheng, Kazuya Okubo, Toru Fujii, Ou Shibata, and Yukiko Fujita. "Study on Effect of Matrix Properties on Fatigue Damage Initiation of Woven Carbon Fabric Vinylester Composites." Applied Mechanics and Materials 541-542 (March 2014): 243–49. http://dx.doi.org/10.4028/www.scientific.net/amm.541-542.243.
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Plain woven carbon fabric composites using different types of vinyl ester (VE) resin with different toughness have been prepared. The mechanical performances were characterized by different tests, such as tensile, tension-tension fatigue, thermoelastic stress analysis (TSA) and scanning electron microscope (SEM). The results showed that with increasing of fracture toughness of VE as well as adhesive strength between VE and carbon fiber (CF), the tensile strength improved by a range from 23.1 to 33.9%, and fatigue life of CF/VE composites increased by several times to several ten times when low toughness VE was used as control resin. The fatigue damage initiation of CF/VE composites has been investigated by thermoelastic stress analysis. It was found that the initiation and growth of fatigue damage such as matrix cracks was delayed, the linkage of matrix cracks in transverse bundles was inhibited with increasing of fracture toughness and interfacial shear strength (IFSS) of matrix resin.
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Harsha, H. M., and K. G. Satish. "Experimental analysis of fracture behavior in ESET jute-natural fiber hybrid composites under eccentric tension." Strength, Fracture and Complexity: An International Journal 18, no. 1 (2024): 3–17. https://doi.org/10.1177/15672069241302928.
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This study investigates the mechanical behavior of hybrid composites reinforced with natural jute fiber and glass fiber in varying volume fractions, using a constant volume of epoxy resin. Specimens were fabricated using the hand layup method and subjected to tensile testing as per ASTM standards. Different volume fractions and fiber orientations were tested under eccentric tensile loading, with varying single edge notch to width (a/W) ratios. The results revealed that as the jute fiber volume fraction increased, both fracture load and fracture toughness decreased. Additionally, fracture load decreased with increasing (a/W) ratio, while fracture toughness showed an increase. Specimens with 0°/90° fiber orientation exhibited the highest fracture load and toughness. Statistical and fractographic analyses validated the experimental findings, with Taguchi method ranking jute fiber percentage as the most significant factor influencing fracture behavior, followed by the (a/W) ratio. ANOVA results confirmed that jute fiber percentage was the dominant factor. Minimal error was observed in the confirmation experiments during regression analysis. Scanning Electron Microscopy (SEM) of fractured surfaces revealed that the interaction between epoxy, jute, and glass fibers had a significant impact on fracture load and toughness. The findings offer an in-depth understanding of the influence of jute fiber content and (a/W) ratio on the mechanical properties of jute-natural epoxy hybrid composites.
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Lin, Shiyun, Chenyun Peng, Fanghang Deng, and Dagang Yin. "Study on the tensile properties of 3D printing cell structure based on fractal theory." Journal of Physics: Conference Series 2783, no. 1 (2024): 012016. http://dx.doi.org/10.1088/1742-6596/2783/1/012016.
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Abstract Using lightweight technology involves optimizing materials, structures, and manufacturing processes to reduce structural weight while meeting performance standards. This technology has emerged as pivotal in advancing the next generation of aerospace equipment. This study employed the 3D printing method using PLA material to produce tensile test specimens of three structures: the concave hexagonal, bionic feather, and standard structures. Tensile and finite element simulation tests were conducted to assess their tensile properties. By comparing crack propagation paths under tensile load, the impact of these paths on structure fracture toughness was analyzed using fractal theory. The findings reveal that distinct structures exhibit varied fracture toughness due to differing crack propagation paths during tensile fracture. Fractal dimensions were calculated for each structure: 1.491 for the concave hexagonal structure, 1.488 for the bionic feather structure, and 1.465 for the standard structure. These dimensions suggest that the concave hexagonal structure possesses the highest fracture toughness among the three structures.
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Yang, Xiao Long, Xiao Dong Tan, Yun Bo Xu, Zhi Ping Hu, Yong Mei Yu, and Di Wu. "Effect of Rolling Process on Impact Toughness in High Strength Low Carbon Bainitic Steel." Materials Science Forum 816 (April 2015): 743–49. http://dx.doi.org/10.4028/www.scientific.net/msf.816.743.
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Based on TMCP and UFC technology, the microstructures and impact toughness of low carbon bainitic steel were studied in this paper. The bainite morphology and fracture surfaces of Charpy impact specimens were observed by SEM, and mechanical properties of bainitic steel were measured by tensile and impact test. The results showed that the yield and tensile strengths of steel were 804MPa and 1015MPa, and elongation was 15.7% when the rolling was finished in the austenite recrystallization region. The steel rolled below Tnr temperature obtained tht yield strength of 930 MPa, tensile strength of 1090 MPa and elongation of 16.2%. However, the impact toughness was deteriorated in the steel rolled above Tnr temperature while the excellent impact toughness existed in the steel rolled below Tnr temperature. The impact toughness of steel rolled below Tnr temperature was 140J at-60°C, while the impact toughness of 15J at the same temperature was obtained for the steel rolled above Tnr temperature. The large cleavage fracture region on the fracture surface occured with the decrease of tested temperature in the steel rolled above Tnr temperature and inevitably reduced the impact toughness, while the main ductile fracture existed in the steel rolled below Tnr temperature at the same temperature. The rolling process of steel can strongly affect impact toughness of low carbon bainitic steel. Hence, the different rolling processes can adjust the occurrence of cleavage fracture and ductile fracture in order to improve the impact toughness.
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Glaskova-Kuzmina, Tatjana, Leons Stankevics, Sergejs Tarasovs, et al. "Effect of Core–Shell Rubber Nanoparticles on the Mechanical Properties of Epoxy and Epoxy-Based CFRP." Materials 15, no. 21 (2022): 7502. http://dx.doi.org/10.3390/ma15217502.
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The aim of the research was to estimate the effect of core–shell rubber (CSR) nanoparticles on the tensile properties, fracture toughness, and glass transition temperature of the epoxy and epoxy-based carbon fiber reinforced polymer (CFRP). Three additives containing CSR nanoparticles were used for the research resulting in a filler fraction of 2–6 wt.% in the epoxy resin. It was experimentally confirmed that the effect of the CSR nanoparticles on the tensile properties of the epoxy resin was notable, leading to a reduction of 10–20% in the tensile strength and elastic modulus and an increase of 60–108% in the fracture toughness for the highest filler fraction. The interlaminar fracture toughness of CFRP was maximally improved by 53% for ACE MX 960 at CSR content 4 wt.%. The glass transition temperature of the epoxy was gradually improved by 10–20 °C with the increase of CSR nanoparticles for all of the additives. A combination of rigid and soft particles could simultaneously enhance both the tensile properties and the fracture toughness, which cannot be achieved by the single-phase particles independently.
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Li, Erqiang, Yanqing Wei, Zhanyang Chen, and Longfei Zhang. "Experimental and Numerical Investigations of Fracture Behavior for Transversely Isotropic Slate Using Semi-Circular Bend Method." Applied Sciences 13, no. 4 (2023): 2418. http://dx.doi.org/10.3390/app13042418.
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Slate with inherently transverse isotropy is abundant in metamorphic rock, in buildings, and in geotechnical engineering worldwide; the tensile and shear fracture behavior of layered slate is vital to know for engineering applications. In this paper, the Brazilian and semi-circular bend (SCB) tests of layered slate were performed. The fracture characteristics of the slate were investigated by numerical simulations developed by the hybrid finite and cohesive element method (FCEM). Results showed that the measured experimental tensile strength, and mode I fracture toughness of layered slate all showed a typical V-type trend as the bedding angle increased from 0° to 90°, and with divider type. The developed empirical relationship between tensile fracture toughness and tensile strength KIC = 0.094σt + 0.036 fitted experimentally and strongly correlated. The mechanical response and fracture patterns predicted by FCEM agreed well with those of the laboratory experiments. Moreover, the shear fracture behavior and mode II fracture toughness of the layered slate were explored by systematic numerical simulations. Research results provide potential insights for further prediction and improvement of the complex fracture behavior of anisotropic rock masses for rock engineering.
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Yuan, Zhi Shan, Zheng Lu, You Hua Xie, Xiu Liang Wu, Sheng Long Dai, and Chang Sheng Liu. "Mechanical Properties of a Novel High-Strength Aluminum-Lithium Alloy." Materials Science Forum 689 (June 2011): 385–89. http://dx.doi.org/10.4028/www.scientific.net/msf.689.385.
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As a heat treatable aluminum alloy to be used in T6 and T8 temper, belongs to Al-Cu-Li system, a novel high-strength aluminum-lithium alloy 2A97 was developed. In order to improve the relationships of strength and ductility and fracture toughness, and to urge the applications in the aeronautical and aerospace industries, the effects of normal heat treatments and thermomechanical heat treatments on the mechanical properties and fracture toughness were investigated by Transmission Electron Microscope(TEM), Scanning Electronic Microscope (SEM), tensile test, and fracture toughness test. The results show that for the alloy aged at 135 °C for 24 h after quenching and 4 percent plastic deformation, its microstructures are strengthened by strain hardening and precipitation hardening, consisting of fine T1phase, θ″/θ′ phase and δ′ phase densely and homogeneously distributed in the matrix. It yields optimum relationship of strength and ductility, fracture toughness, its σ0.2, σband δ5are 454 MPa, 536 MPa, and 11.8%, respectively. It yields 43.5 MPa·m1/2of Kqvalues higher than that of 42.5 MPa·m1/2 in T6 temper. The fracture morphologies of impact tensile samples of fracture toughness test and normal tensile test were observed, indicating the dominance of intergranular failure and subintergranular failure with some dimples and trangranular failure.
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Liu, Yongwei, Fuwen Chen, Guanglong Xu, Yuwen Cui, and Hui Chang. "Correlation between Microstructure and Mechanical Properties of Heat-Treated Ti–6Al–4V with Fe Alloying." Metals 10, no. 7 (2020): 854. http://dx.doi.org/10.3390/met10070854.
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The microstructure and mechanical properties of a newly developed Fe-microalloyed Ti–6Al–4V titanium alloy were investigated after different heat treatments. The volume fraction and the morphological features of the lamellar α phase had significant effects on the alloy’s mechanical performance. A dataset showing the relationship between microstructural features and tensile strength, elongation, and fracture toughness was developed. A high aging temperature resulted in high plasticity and fracture toughness, but relatively low strength. The high strength favored the fine α and the slender β. The high aspect ratio of lamellar α led to high strength but low fracture toughness. The alloy with ~84 vol % α exhibited the highest strength and lowest fracture toughness because the area of its α/β-phase interface was the highest. Optimal comprehensive mechanical performance and heat-treatment procedures were thus obtained from the dataset. Optimal tensile strength, yield strength, elongation, and fracture toughness were 999 and 919 MPa, 10.4%, and 94.4 MPa·m1/2, respectively.
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Bhattacharyya, Kushal. "A Comprehensive Study of Fracture Toughness Determination from Conventional and Unconventional Methods." Defence Science Journal 72, no. 2 (2022): 250–57. http://dx.doi.org/10.14429/dsj.72.16453.
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In this work fracture toughness is determined by the Toughness model; Critical Stress-Strain Model and Energy release rate model using unconventional test method referred to as Spherical Indentation test (SIT) to reduce the large and costly experimental set up as required in Conventional Fracture Toughness Test. The toughness model correlates the indentation energy to fracture with fracture toughness, Critical Stress-Strain Model assumes that the critical fracture toughness is equal to the critical plastic work done by the material when a crack tends to propagate and as per the Energy release rate model, indentation depth is given by loading-unloading cycles. The unloading slope which is elastic provides the reduced Young’s Modulus of the material from each unloading cycle which reflects the occurrence of damage in the material. For the determination of contact radius at different indentation points, finite element analysis is performed using the material data obtained from the tensile test result obtained from the previous work of the author. Conventional method using the Compact Tension (CT) and Three-Point Bending (TPB) specimens for the same material is used to determine the fracture toughness and compared with the above-described model.
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Hlebová, Stanislava, and Ladislav Pešek. "Toughness of Ultra High Strength Steel Sheets ." Materials Science Forum 782 (April 2014): 57–60. http://dx.doi.org/10.4028/www.scientific.net/msf.782.57.
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Currently only few methods exist for thin steel sheet testing, especially based on fracture mechanics concept. Charpy impact test is one of the most used method for testing notch toughness and fracture behaviors because of the simplicity and the other advantages [. This article deals with toughness testing of automotive ultra high strength steel sheets (UHSS). Several standard types of toughness test that generate data for specific loading conditions and/or component design approaches exist. Two definition of toughness will be discussed: i) Charpy V-notch toughness, method includes joining of thin steel sheets to one compact unit and ii) material (tensile) toughness [. Two steels were used, DP1000 and 1400M of 1,8 mm thickness and two joining techniques: bonding with adhesives and joining with holders. Effect of material, joining technology, structural adhesives, and number of joined plates on the toughness values was quantified at the room temperature. Toughness of steels by the tensile test was added for comparison. Fracture surface was observed using scanning electron microscope analysis.
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Durmuş, Ali, Hakan Aydın, Mümin Tutar, Ali Bayram, and Kurtuluş Yiğit. "Effect of the microstructure on the notched tensile strength of as-cast and austempered ductile cast irons." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 226, no. 9 (2012): 2214–29. http://dx.doi.org/10.1177/0954406211433248.
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In this study, the effect of microstructure on the mechanical properties of four types of ductile cast irons with different morphologies was investigated using circumferentially notched cylindrical specimens with different notch root radii. These cast irons were also austempered using the same austempering heat treatment to make a comparison with the as-cast samples. Characterization of the specimens has been carried out by means of microstructure, hardness, tensile properties, notch tensile strength, notch sensitivity, fracture toughness, and fractography. A mixture of ferrite and pearlite in the microstructure of cast irons gives rise to a material of the highest tensile strength, notch tensile strength, and fracture toughness properties with the intermediate ductility and notch sensitivity. A higher pearlite in the matrix of cast irons gives very important mechanical properties such as hardness and strength, but brittleness of the matrix andnotch sensitivity are greatly increased. Austempering significantly increased the mechanical properties and also reduced the difference between the mechanical properties of the cast irons. Austempered ferritic ductile irons exhibited the highest notch tensile strength and fracture toughness, and the high tensile strength and the intermediate ductility properties with the lowest notch sensitivity, whereas austempered pearlitic ductile irons had the lowest tensile strength, ductility, notch tensile strength, fracture toughness, and the intermediate notch sensitivity properties. The mechanical properties of the as-cast and austempered ductile irons have increased almost linearly with increase in the notch root radius.
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Ogaili, Ahmed Ali Farhan, Ali Basem, Mohammed Salman Kadhim, et al. "The Effect of Chopped Carbon Fibers on the Mechanical Properties and Fracture Toughness of 3D-Printed PLA Parts: An Experimental and Simulation Study." Journal of Composites Science 8, no. 7 (2024): 273. http://dx.doi.org/10.3390/jcs8070273.
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The incorporation of fiber reinforcements into polymer matrices has emerged as an effective strategy to enhance the mechanical properties of composites. This study investigated the tensile and fracture behavior of 3D-printed polylactic acid (PLA) composites reinforced with chopped carbon fibers (CCFs) through experimental characterization and finite element analysis (FEA). Composite samples with varying CCF orientations (0°, 0°/90°, +45°/−45°, and 0°/+45°/−45°/90°) were fabricated via fused filament fabrication (FFF) and subjected to tensile and single-edge notched bend (SENB) tests. The experimental results revealed a significant improvement in tensile strength, elastic modulus, and fracture toughness compared to unreinforced PLA. The 0°/+45°/90° orientation exhibited a 3.6% increase in tensile strength, while the +45°/−45° orientation displayed a 29.9% enhancement in elastic modulus and a 29.9% improvement in fracture toughness (259.12 MPa) relative to neat PLA (199.34 MPa√m). An inverse correlation between tensile strength and fracture toughness was observed, attributed to mechanisms such as crack deflection, fiber bridging, and fiber pull-out facilitated by multi-directional fiber orientations. FEA simulations incorporating a transversely isotropic material model and the J-integral approach were conducted using Abaqus, accurately predicting fracture toughness trends with a maximum discrepancy of 8% compared to experimental data. Fractographic analysis elucidated the strengthening mechanisms, highlighting the potential of tailoring CCF orientation to optimize mechanical performance for structural applications.
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Kasapi, M. A., and J. M. Gosline. "Strain-rate-dependent mechanical properties of the equine hoof wall." Journal of Experimental Biology 199, no. 5 (1996): 1133–46. http://dx.doi.org/10.1242/jeb.199.5.1133.
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The mechanical properties of fully hydrated equine hoof wall were examined at various loading rates in compact tension (CT) fracture, tensile and three-point bending dynamic tests to determine possible effects of hoof wall viscoelasticity on fracture toughness and tensile parameters. Four cross-head rates were used in CT tests: 1.7 x 10(-5), 1.7 x 10 (-3), 1.7 x 10(-2) and 2.5ms-1; four strain rates were used in tensile tests: 1.6 x 10(-3), 3.2 x 10(-2), 0.33 and 70s(-1). Speeds for the highest test rates were achieved using a large, custom-built impact pendulum. Bending test frequencies ranged from 0.04 to 200 Hz. In CT tests, both the initial modulus Ei and the stress intensity factor K rose with increasing strain rate (from 0.38 to 0.76 GPa for Ei and from 0.71 to 1.4 MN m-3/2 for K), whereas the fracture toughness parameter J remained constant at 12kJm-2. All tensile parameters except ultimate strain were sensitive to strain rate. Ei, total energy to breakage and maximum stress rose with increasing strain rate from 0.28 to 0.85 GPa, from 5.4 to 9.7 MJm-3 and from 17 to 31 MPa, respectively. Data from low-amplitude dynamic tests agreed well with Ei trends from CT and tensile tests. Direction of crack growth differed through the thickness of the wall, the pattern of which resembled a trilaminar ply. Although scanning electron microscopic examination of fracture surfaces revealed a decreasing pseudo-ductile behaviour with increasing strain rate, and ultimate tensile parameters are positively affected, equine hoof wall viscoelasticity does not appear to compromise fracture toughness at high strain rates.
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Shimada, Yusuke, Yoichi Kayamori, Shohei Nishida, Mitsuhiro Matsuda, and Kazuki Takashima. "Micromechanical Characterisation of Microstructure in Weld Heat Affected Zone of Structural Steel." Key Engineering Materials 525-526 (November 2012): 585–88. http://dx.doi.org/10.4028/www.scientific.net/kem.525-526.585.
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Microstructures in the weld heat affected zone (HAZ) can cause a decrease in fracture toughness, and evaluating the effect of microstructures on fracture toughness is helpful in understanding the cause of the fracture toughness decrease. In this study, micro-sized tensile specimens were sampled from base metal and HAZ, and the mechanical properties and fracture behaviours of different steel microstructures were directly investigated by micro-sized mechanical testing.
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Wu, Ming Wei, Guo Jiun Shu, and Shih Hsien Chang. "The Impact Toughness and Fracture Behavior of Ni-Containing Powder Metal Steels." Advanced Materials Research 538-541 (June 2012): 1594–600. http://dx.doi.org/10.4028/www.scientific.net/amr.538-541.1594.
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The toughness of powder metal (PM) steel is always inferior due to the presence of pores. An alloying element is typically found to improve the tensile strength, while sacrificing toughness. These issues prohibit the development of high-strength PM steels with satisfactory toughness. To formulate high-strength PM steels with superior toughness, the effects of Cr and Mo on the impact toughness and fracture behaviors of Ni-containing PM steels were investigated. The results indicated that both 1.5wt% Cr and 1.5 wt% Mo additives can improve the microstructures and tensile strengths of Ni-containing PM steels. However, while 1.5 wt % Mo apparently impairs the toughness, 1.5 wt % Cr does not. The addition of 1.5 wt% Cr results in the formation of Ni-rich martensite, which is strong and tough, thereby improving the tensile strength by 150% without sacrificing toughness.
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Kong, Byeong Seo, Ji Ho Shin, Changheui Jang, and Hyoung Chan Kim. "Measurement of Fracture Toughness of Pure Tungsten Using a Small-Sized Compact Tension Specimen." Materials 13, no. 1 (2020): 244. http://dx.doi.org/10.3390/ma13010244.
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The evaluation of fracture toughness of pure tungsten is essential for the structural integrity analysis in a fusion reactor. Therefore, the accurate quantification of fracture toughness of tungsten alloys is needed. However, due to the inherent brittleness of tungsten, it is difficult to introduce a sharp fatigue pre-crack needed for the fracture toughness test. In this study, a novel fatigue pre-cracking method was developed and applied to the small-sized disc-type compact tension (DCT) specimens of double-forged pure tungsten. To overcome the brittleness and poor oxidation resistance, a low-frequency tensile fatigue pre-cracking was performed at 600 °C in Ar environment, which resulted in the introduction of a sharp pre-crack to DCT specimens. Then, fracture toughness tests were conducted at room temperature (RT), 400 °C, and 700 °C in air and Ar gas environments using as-machined and pre-cracked DCT specimens. At RT and 400 °C, the test environment and crack tip radius did not affect the fracture toughness measurement. However, at 700 °C, the Ar gas environment and the presence of a sharp fatigue pre-crack resulted in a decrease in the measured fracture toughness. Thus, it was suggested that, for the conservative fracture toughness measurement of pure tungsten, fatigue pre-cracking and fracture toughness test should be performed in an inert environment, especially for high-temperature tests.
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Bona, A. Della, K. J. Anusavice, and J. J. Mecholsky. "Apparent Interfacial Fracture Toughness of Resin/Ceramic Systems." Journal of Dental Research 85, no. 11 (2006): 1037–41. http://dx.doi.org/10.1177/154405910608501112.
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We suggest that the apparent interfacial fracture toughness (KA) may be estimated by fracture mechanics and fractography. This study tested the hypothesis that the KA of the adhesion zone of resin/ceramic systems is affected by the ceramic microstructure. Lithia disilicate-based (Empress2-E2) and leucite-based (Empress-E1) ceramics were surface-treated with hydrofluoric acid (HF) and/or silane (S), followed by an adhesive resin. Microtensile test specimens (n = 30; area of 1 ± 0.01 mm2) were indented (9.8 N) at the interface and loaded to failure in tension. We used tensile strength (σ) and the critical crack size (c) to calculate KA (KA = Yσc1/2) (Y = 1.65). ANOVA and Weibull analyses were used for statistical analyses. Mean KA (MPa·m1/2) values were: (E1HF) 0.26 ± 0.06; (E1S) 0.23 ± 0.06; (E1HFS) 0.30 ± 0.06; (E2HF) 0.31 ± 0.06; (E2S) 0.13 ± 0.05; and (E2HFS) 0.41 ± 0.07. All fractures originated from indentation sites. Estimation of interfacial toughness was feasible by fracture mechanics and fractography. The KA for the systems tested was affected by the ceramic microstructure and surface treatment.
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Poe, C. C. "A Parametric Study of Fracture Toughness of Fibrous Composite Materials." Journal of Offshore Mechanics and Arctic Engineering 111, no. 3 (1989): 161–69. http://dx.doi.org/10.1115/1.3257143.
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Impacts to fibrous composite laminates by objects with low velocities can break fibers giving cracklike damage. The damage may not extend completely through a thick laminate. The tension strength of these damaged laminates is reduced much as is that of cracked metals. The fracture toughness depends on fiber and matrix properties, fiber orientations, and stacking sequence. Accordingly, a parametric study was made to determine how fiber and matrix properties and fiber orientations affect fracture toughness and notch sensitivity. The values of fracture toughness were predicted from the elastic constants of the laminate and the failing strain of the fibers using a general fracture toughness parameter developed previously. For a variety of laminates, values of fracture toughness from tests of center-cracked specimens and values of residual strength from tests of thick laminates with surface cracks were compared to the predictions to give credibility to the study. In contrast to the usual behavior of metals, it is shown that both ultimate tensile strength and fracture toughness of composites can be increased without increasing notch sensitivity, and that laminates with surface cracks can fail in two stages, giving some degree of redundancy.
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Kumar, Ravi Ranjan, and P. K. Ghosh. "Fracture Mechanics of Conventional and Narrow Groove Pulse Current Gas Metal Arc Welds of HSLA Steel." Materials Science Forum 710 (January 2012): 451–56. http://dx.doi.org/10.4028/www.scientific.net/msf.710.451.
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Mechanical and fracture properties of 20MnMoNi55 grade high strength low alloy (HSLA) steel welds have been studied. The weld joints were made using Gas Tungsten Arc Welding (GTAW), Shielded Metal Arc Welding (SMAW) and Pulse Gas Metal Arc Welding (P-GMAW) methods on conventional V-groove (V-Groove) and Narrow groove (NG-13). The base metal and weld metal were characterised in terms of their metallurgical, mechanical and fracture toughness properties by following ASTM procedures. The J-Integral fracture test was carried out using compact tension C(T) specimen for base and weld metal. The fracture toughness and tensile properties of welds have been correlated with microstructure. In conventional V-groove welds prepared by P-GMAW shows the improvement in initiation fracture toughness (JIC) as compared to the weld prepared by SMAW. Similar improvements in tensile properties have also been observed. This is attributed to reduction in co-axial dendrite content due to lower heat input during P-GMAW process as compared to SMAW. In the narrow groove P-GMA weld prepared at f value of 0.15 has shown relative improvement of JIC as compared to that of the weld prepared by SMAW process.
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Zhou, Lingzhu, Yu Zheng, Linsheng Huo, Yuxiao Ye, Xiaolu Wang, and Gangbing Song. "Fracture behaviors of HVFA-SCC mixed with seawater and sea-sand under three-point bending." Advances in Structural Engineering 25, no. 4 (2022): 716–35. http://dx.doi.org/10.1177/13694332211027313.
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This paper aims to study the fracture behaviors of high-volume fly ash-self-compacting concrete (HVFA-SCC) mixed with seawater and sea-sand (SWSS) or freshwater and river sand (FWRS). Three-point bending test were performed on 24 notched beams fabricated with varying in replacement ratio of fly ash (0%, 30%, 50%, and 70%) and the type of water and sand (SWSS and FWRS). The initial and unstable fracture toughness of these test specimens are determined by the double- K fracture model. The effect of fly ash replacement ratio and type of water and sand on the fracture parameters is analyzed and discussed. In addition, the cohesive fracture toughness of all the test specimens is calculated by using Gauss–Chebyshev integral method and the weight function method based on the bilinear tensile softening curve given in CEP-FIP Model Code. A comparison of fracture toughness parameters of determined from the experimental approach and analytical approaches is presented in these SCC specimens. Results show that SCC mixed with SWSS replacing FWRS can improve the unstable fracture toughness and fracture energy, and decrease its brittleness behavior. The cohesive fracture toughness of SWSS-SCC specimens is underestimated by these analytical methods based on the tensile softening curve given in CEP-FIP Model Code.
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Wu, Hai Jun, Kun Sun, Chao Guo, Feng Lei Huang, and Xiu Fang Ma. "Experimental Studies on Fracture Properties of 30CrMnSiNi2A Steel." Advanced Materials Research 875-877 (February 2014): 478–84. http://dx.doi.org/10.4028/www.scientific.net/amr.875-877.478.
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The 30CrMnSiNi2A steel has been commonly used in the national defense industry and engineering areas. The fracture properties of the material are studied by dynamic tensile tests on a traditional Hopkinson system and three-point bend tests on a modified Hopkinson loading system. The dynamic tensile experiments results show that 30CrMnSiNi2A steel is sensitive of the strain rate. The dynamic fracture toughness of the material increases with the rise of loading rate, but its value is less than the static fracture toughness value. Move over, the fracture mechanism is investigated through macroscopic and microstructural analysis, which reveals that the fracture mechanism of 30CrMnSiNi2A belongs to quasi-cleavage fracture.
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Смирнов, И. В. "Конструкционные прочностные параметры и разрушение ультрамелкозернистого титана Grade 4, полученного методом равноканального углового прессования РКУП-К". Журнал технической физики 89, № 4 (2019): 541. http://dx.doi.org/10.21883/jtf.2019.04.47309.266-18.
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AbstractProcessing of metals and alloys by severe plastic deformation (SPD) is accompanied by refinement of the material grain structure, which can increase their physicomechanical properties, for instance, unique tensile strength. However, studies of mechanical properties of materials after SPD are usually limited by tensile tests and other properties of strength and fracture are not sufficiently considered. This article presents experimental studies of ultimate tensile strength, impact toughness, fracture toughness, as well as respective surfaces of fracture of initial and ultrafine-grained pure Grade 4 titanium fabricated by continuous equal channel angular pressing. The results demonstrated that upon high ultimate tensile strength after SPD the material demonstrates decreased resistance against initiation and propagation of cracks upon single loading. The fracture surface of both states of titanium structure reveals mainly localized plastic deformation.
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Ku, H., W. Xiang, and N. Pattarachaiyakoop. "Mathematical Modeling of the Fracture Toughness of Phenol Formaldehyde Composites Reinforced with E-Spheres." Advanced Materials Research 79-82 (August 2009): 1165–68. http://dx.doi.org/10.4028/www.scientific.net/amr.79-82.1165.
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The fracture toughness of SLG filled phenolic composites have been determined by short bar tests. It is expensive to prepare the samples for the tests. Therefore, it is necessary to develop a mathematical model that will predict the fracture toughness of particulate filled phenolic composites. Mathematical models for tensile strength, Young’s modulus are available but not for impact strength and fracture toughness. There is no sign that it can be built up from simple mathematical model; polynomial interpolation using Lagrange’s method was therefore employed to generate the fracture toughness model using the data obtained from experiments. From experiments, it was found that the trend of the fracture toughness of the samples cured conventionally was similar to that cured in microwaves; it is therefore possible to predict the fracture toughness of the samples cured in microwaves from shifting the mathematical model generated for fracture toughness of samples post-cured in conventional oven. The shifted model represented the fracture toughness of the samples cured in microwaves vey well.
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Achla, Saurindra Nath Maiti та Josemon Jacob. "Post-yield fracture correlations to morphological and micromechanical response of poly(ε-caprolactone)-based biocomposites". Journal of Thermoplastic Composite Materials 31, № 5 (2017): 575–97. http://dx.doi.org/10.1177/0892705717713242.
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The present work investigates the effect of jack wood flour (JWF) content on the fracture toughness, tensile, impact, and morphological behavior of the prepared green biocomposites. From 0 to 35 wt% (volume fraction ( Φf) = 0–0.34) of JWF was incorporated as a reinforcing biodegradable filler into poly(ε-caprolactone) (PCL) matrix by melt compounding in a twin screw extruder. The tensile modulus increases by 80.48% at the highest Φf = 0.34, though marginal increment (13.71%) in the yield strength was registered. A sharp reduction in notched Izod impact strength (85%) was observed with increasing JWF content. The fracture toughness of the prepared biocomposites based on post-yield fracture mechanics concept was investigated by essential work of fracture (EWF) methodology. Incorporation of JWF into PCL matrix diminishes the EWF ( we), while increasing the non-essential work of fracture ( βwp). In the biocomposites, principally two mechanisms governed the fracture deformation. Large JWF particles act as stress concentration points and favor the crack initiation, while the smaller particles favor fibrillation which arrests the crack propagation enhancing the parameter βwp at lower concentration of JWF. Freeze-fractured surfaces show a degree of phase adhesion at lower Φf of JWF. The phase adhesion parameter obtained from micromechanical analysis of tensile properties suggesting the mechanical interlocking and interaction between PCL and JWF.
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Feng, Gan, Xiao-chuan Wang, Yong Kang, Shi-gang Luo, and Yao-qing Hu. "Effects of Temperature on the Relationship between Mode-I Fracture Toughness and Tensile Strength of Rock." Applied Sciences 9, no. 7 (2019): 1326. http://dx.doi.org/10.3390/app9071326.
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Fracture toughness is used to characterize rock resistance to fracturing and it is important in theoretical research and engineering applications. Mode-I fracture toughness can be predicted on the basis of an empirical relationship between fracture toughness (KIC) and tensile strength (σt). In underground engineering, rocks are often subjected to different temperatures. Therefore, this paper explores the effect of temperature on the relationship between mode-I fracture toughness and tensile strength. The results show that the change trends in the KIC and σt values of rocks at temperatures from 20 °C to 600 °C are broadly consistent with each other. For rocks heat-treated to the same temperature, the KIC of the rock increases with an increase in σt. This positive correlation between KIC and σt is different in rocks heat-treated to different temperatures. Critical crack propagation radius (rIC) is an important factor in the relationship between KIC and σt and is related to the type of rock and the conditions under which it is tested. For the same rock, rIC is quite different after it has been exposed to different temperatures. The positive correlation between KIC and σt results from a similarity in the fracture morphology and properties of failure when rock is destroyed in fracture and tensile tests.
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Li, Xiangyu, Fugang Li, Minzu Liang, Kefan Zhang, and Zhandong Tian. "Research on Dynamic Constitutive Model and Fracture Characteristics of Two High Strength Steels." Journal of Physics: Conference Series 2168, no. 1 (2022): 012016. http://dx.doi.org/10.1088/1742-6596/2168/1/012016.
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Abstract 58SiMn and 50SiMnVB are commonly used shell materials in bombs, and their dynamic constitutive model and fracture properties directly determine the mass distribution of the bomb. Tensile tests were carried out on two high-strength steels, and the parameters of the yield point, tensile strength and plastic failure strain as well as the John-Cook model were determined. The fracture morphologies of the two steels in the quasi-static tension and in the dynamic tension were analyzed. The research results show that the yield strength of 58SiMn steel remains unchanged with increasing strain rate. The yield strength and tensile strength of 50SiMnVB increase as the rate of elongation increases, and the ability to plastically deform decreases, which shows the properties of embrittlement under high speed loading. With the same elongation rate, 50SiMnVB steel has higher strength and toughness. 58SiMn steel is a tensile brittle fracture from a macroscopic point of view and a quasi-split fracture from a microscopic point of view; 50SiMnVB steel is a mixed lap shear fracture under axial tensile load. With increasing loading rate, the tensile fracture tends to pure shear fracture.
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Kwon, Woong, Minwoo Han, Jongwon Kim, and Euigyung Jeong. "Comparative Study on Toughening Effect of PTS and PTK in Various Epoxy Resins." Polymers 13, no. 4 (2021): 518. http://dx.doi.org/10.3390/polym13040518.
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This study investigated the toughening effect of in situ polytriazoleketone (PTK) and polytriazolesulfone (PTS) toughening agent when applied to various epoxy resins, such as diglycidyl ether of bisphenol A (DGEBA), diglycidyl ether of bisphenol F (DGEBF), and triglycidyl p-aminophenol (TGAP) with 3,3′-diaminodiphenylsulfone as a curing agent. The fracture toughness, tensile properties, and thermal properties of the prepared epoxy samples were evaluated and compared. When PTK was mixed with DGEBF, the fracture toughness was improved by 27% with 8.6% increased tensile strength compared to the untoughened DGEBF. When PTS was mixed with TGAP, the fracture toughness was improved by 51% without decreasing tensile properties compared to the untoughened TGAP. However, when PTK or PTS was mixed with other epoxy resins, the fracture toughness decreased or improved with decreasing tensile properties. This is attributed to the poor miscibility between the solid-state monomer of PTK (4,4′-bis(propynyloxy)benzophenone (PBP)) or PTS (4,4′-sulfonylbis(propynyloxy)benzene (SPB)) and the epoxy resin, resulting in the polymerization of low molecular weight PTK or PTS in epoxy resin. Therefore, the toughening effect of PTK or PTS can be maximized by the appropriate selection of epoxy resin based on the miscibility between PBP or SPB and the resin.
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Abu-Shanab, O. L., C. P. Chang, and M. D. Soucek. "Polyphosphazene Toughened PMR-type Thermosets." High Performance Polymers 8, no. 3 (1996): 455–73. http://dx.doi.org/10.1088/0954-0083/8/3/010.
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Two new polyphosphazenes, poly(4-maleimidophenoxy/phenoxy)phosphazene and poly(4-phthalimidophenoxy/phenoxy)phosphazene, were prepared and used to toughen a PMR polyimide designated LaRCTMRP46. These toughened polyimides were evaluated as thin films with a 0–40 wt% range of polyphosphazene to polyimide. The structure–property relationships of these inorganic/organic polymeric matrices were studied and evaluated in terms of fracture toughness, thermo-oxidative stability, and thermal, mechanical, and tensile properties. The hybrid systems revealed an increase in fracture toughness up to 20 wt% polyphosphazene load without any substantial loss in tensile properties. With 5 wt% poly(4-phthalimidophenoxy/phenoxy)phosphazene loading, the fracture toughness of the semi-interpenetrating network was increased by 124%. When 10 wt% poly(4- maleimidophenoxy/phenoxy)phosphazene loading was used, the fracture toughness of the grafted copolymer was improved by 217%. In addition, substantial enhancement in thermo-oxidative stability was also observed.
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Ray, Kalyan Kumar, and R. N. Jha. "Probabilistic Fracture Resistance of a Forged Quality Medium Carbon Alloy Steel." Key Engineering Materials 488-489 (September 2011): 53–56. http://dx.doi.org/10.4028/www.scientific.net/kem.488-489.53.
Full textAbstract:
Impact and fracture toughness of a large number of medium carbon alloy steel specimens have been ascertained using standard ASTM procedures, apart from examining their chemistry, microstructure, cleanliness, tensile behaviour and fracture surfaces. The results indicate that the scatter associated with ductility, impact and fracture toughness is considerable unlike that for strength or hardness. Analyses of the role of undesirable elements on toughness properties indicate that the scatter associated with fracture resistance of the steel primarily originates from the amount of tramp elements.