Pub Date : 2023-10-09DOI: 10.1016/j.finmec.2023.100242
Shiva Prashanth Kumar Kodicherla , Minyi Zhu , Guobin Gong , Stephen Wilkinson
This paper investigates the undrained behaviour of granular clumps after isotropic and Ko-consolidation paths using a three-dimensional discrete element method (3D-DEM). Four randomly chosen clumped particles with a wide range of densification indexes, ID, and mean confining stresses, p' were considered. The specimens were sheared to the deviatoric strain, of 40 % to reach the critical state (CS) conditions. It was found from the results that a unique critical state line (CSL) was achieved, irrespective of consolidation paths. The micro-mechanical quantities such as the average coordination number (CN) and von Mises fabric in terms of the second invariant of deviatoric fabric, FvM, also reached CS values. Irrespective of the consolidation paths, unique relationships were found between and . The stress-fabric joint invariant, KF established a unique relationship with and e, which forms a relationship in the space and the projection of this relationship in the plane confirms the classical CSL. Moreover, the flow potential (uF), stress ratio at instability (), and average coordination number at instability (CNIS) showed no dependency on the consolidation paths, while a dependency was observed for the second-order deviator fabric, FvM.
{"title":"Exploring the undrained behaviour of granular clumps after isotropic and Ko-consolidation paths using DEM","authors":"Shiva Prashanth Kumar Kodicherla , Minyi Zhu , Guobin Gong , Stephen Wilkinson","doi":"10.1016/j.finmec.2023.100242","DOIUrl":"https://doi.org/10.1016/j.finmec.2023.100242","url":null,"abstract":"<div><p>This paper investigates the undrained behaviour of granular clumps after isotropic and <em>K</em><sub>o</sub>-consolidation paths using a three-dimensional discrete element method (3D-DEM). Four randomly chosen clumped particles with a wide range of densification indexes, <em>I</em><sub>D</sub>, and mean confining stresses, <em>p</em>' were considered. The specimens were sheared to the deviatoric strain, <span><math><msub><mrow><mi>ε</mi></mrow><mi>q</mi></msub></math></span> of 40 % to reach the critical state (CS) conditions. It was found from the results that a unique critical state line (CSL) was achieved, irrespective of consolidation paths. The micro-mechanical quantities such as the average coordination number (CN) and von Mises fabric in terms of the second invariant of deviatoric fabric, <em>F</em><sub>vM</sub>, also reached CS values. Irrespective of the consolidation paths, unique relationships were found between <span><math><mrow><mi>e</mi><mo>−</mo><mi>log</mi><mo>(</mo><msup><mrow><mi>p</mi></mrow><mo>′</mo></msup><mo>)</mo></mrow></math></span>and <span><math><mrow><mi>C</mi><mi>N</mi><mo>−</mo><mtext>log</mtext><mo>(</mo><msup><mi>p</mi><mo>′</mo></msup><mo>)</mo></mrow></math></span>. The stress-fabric joint invariant, <em>K</em><sub>F</sub> established a unique relationship with <span><math><msup><mrow><mi>p</mi></mrow><mo>′</mo></msup></math></span>and <em>e</em>, which forms a relationship in the <span><math><mrow><msub><mi>K</mi><mi>F</mi></msub><mo>−</mo><msup><mi>p</mi><mo>′</mo></msup><mo>−</mo><mi>e</mi></mrow></math></span> space and the projection of this relationship in the <span><math><mrow><mi>e</mi><mo>−</mo><mi>log</mi><mo>(</mo><msup><mrow><mi>p</mi></mrow><mo>′</mo></msup><mo>)</mo></mrow></math></span> plane confirms the classical CSL. Moreover, the flow potential (<em>u</em><sub>F</sub>), stress ratio at instability (<span><math><msub><mi>η</mi><mrow><mi>I</mi><mi>S</mi></mrow></msub></math></span>), and average coordination number at instability (CN<sub><em>IS</em></sub>) showed no dependency on the consolidation paths, while a dependency was observed for the second-order deviator fabric, <em>F</em><sub>vM</sub>.</p></div>","PeriodicalId":93433,"journal":{"name":"Forces in mechanics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49752319","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-10-06DOI: 10.1016/j.finmec.2023.100239
Sikang Yan , Alexander Schlüter , Erik Faust , Ralf Müller
The phase field model - a powerful tool - has been well established to simulate the fatigue crack evolution behavior. However, it is still hard to understand how each energy component in the phase field model contributes to crack evolution since the phase field method is based on an energetic criterion. In this work, we borrow the concept of configurational forces and show a straightforward way to examine the energetic driving forces in the phase field fatigue model. Results show that different parts of the configurational forces provide different energetic contributions during crack propagation.
{"title":"Configurational forces in a phase field model for the cyclic fatigue of heterogeneous materials","authors":"Sikang Yan , Alexander Schlüter , Erik Faust , Ralf Müller","doi":"10.1016/j.finmec.2023.100239","DOIUrl":"https://doi.org/10.1016/j.finmec.2023.100239","url":null,"abstract":"<div><p>The phase field model - a powerful tool - has been well established to simulate the fatigue crack evolution behavior. However, it is still hard to understand how each energy component in the phase field model contributes to crack evolution since the phase field method is based on an energetic criterion. In this work, we borrow the concept of configurational forces and show a straightforward way to examine the energetic driving forces in the phase field fatigue model. Results show that different parts of the configurational forces provide different energetic contributions during crack propagation.</p></div>","PeriodicalId":93433,"journal":{"name":"Forces in mechanics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49755577","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-10-06DOI: 10.1016/j.finmec.2023.100240
M. Karthick , R. Santhanakrishnan
In order to effectively mitigate the risk of bird strikes, it is imperative that radomes situated in areas prone to such incidents possess the capability to endure the impact loads caused by bird collisions. Additionally, these radomes must maintain their electromagnetic transparency. Therefore, glass fibre reinforced polymer (GFRP) with Nomex honeycomb sandwich material is used for radome structural design. The current research is intended to examine the dynamic behavior of sandwich composite panels in order to determine the penetration velocity by testing them at three distinct bird impact velocities, such as 88 m/s, 135 m/s, and 153 m/s. It is necessary to find the velocity at which the bird will penetrate / rupture the radome for the safety of Antenna / Electronic units mounted behind the radome. Finite element explicit code LS-DYNA simulates all three impacts. Extension of the simulation estimated the threshold bird impact velocity to be 146 m/s at which it penetrates the sandwich panel under fixture-controlled boundary condition.
{"title":"Experimental and numerical investigation on GFRP- aramid honeycomb sandwich panel under bird impact: Estimation of penetration velocity","authors":"M. Karthick , R. Santhanakrishnan","doi":"10.1016/j.finmec.2023.100240","DOIUrl":"https://doi.org/10.1016/j.finmec.2023.100240","url":null,"abstract":"<div><p>In order to effectively mitigate the risk of bird strikes, it is imperative that radomes situated in areas prone to such incidents possess the capability to endure the impact loads caused by bird collisions. Additionally, these radomes must maintain their electromagnetic transparency. Therefore, glass fibre reinforced polymer (GFRP) with Nomex honeycomb sandwich material is used for radome structural design. The current research is intended to examine the dynamic behavior of sandwich composite panels in order to determine the penetration velocity by testing them at three distinct bird impact velocities, such as 88 m/s, 135 m/s, and 153 m/s. It is necessary to find the velocity at which the bird will penetrate / rupture the radome for the safety of Antenna / Electronic units mounted behind the radome. Finite element explicit code LS-DYNA simulates all three impacts. Extension of the simulation estimated the threshold bird impact velocity to be 146 m/s at which it penetrates the sandwich panel under fixture-controlled boundary condition.</p></div>","PeriodicalId":93433,"journal":{"name":"Forces in mechanics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49755579","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-10-05DOI: 10.1016/j.finmec.2023.100238
Dhiraj P. Bhaskar, Santosh V. Bhaskar, Sachin S. Raj, L.S. Dhamande
Employing innovative kinematic function, a new inverse trigonometric shear deformation theory (nITSDT), variationally suitable, is developed to acquire pertinent data on the bending of sandwich plates subjected to transverse loads with variable aspect ratios(S). This nITSDT eliminates the need for shear correction factors since the transverse shear stress is directly determined by constitutive relations on the two extreme faces of sandwich plate satisfying the shear stress free surface circumstances. The governing equations and boundary conditions of the nITSDT are obtained by applying the dynamic version of the virtual work principle. For sandwich plates with simplly supports, solution is given by MATLAB code using Finite Element (FE) based on nITSDT. The findings of displacements and stresses are supported by those of more comprehensive theories, and the exact solution serves to highlight the viability of the proposed theory.
{"title":"Numerical investigation of sandwich plate in bending by a new inverse shear deformation theory based on finite element analysis","authors":"Dhiraj P. Bhaskar, Santosh V. Bhaskar, Sachin S. Raj, L.S. Dhamande","doi":"10.1016/j.finmec.2023.100238","DOIUrl":"https://doi.org/10.1016/j.finmec.2023.100238","url":null,"abstract":"<div><p>Employing innovative kinematic function, a new inverse trigonometric shear deformation theory (nITSDT), variationally suitable, is developed to acquire pertinent data on the bending of sandwich plates subjected to transverse loads with variable aspect ratios(S). This nITSDT eliminates the need for shear correction factors since the transverse shear stress is directly determined by constitutive relations on the two extreme faces of sandwich plate satisfying the shear stress free surface circumstances. The governing equations and boundary conditions of the nITSDT are obtained by applying the dynamic version of the virtual work principle. For sandwich plates with simplly supports, solution is given by MATLAB code using Finite Element (FE) based on nITSDT. The findings of displacements and stresses are supported by those of more comprehensive theories, and the exact solution serves to highlight the viability of the proposed theory.</p></div>","PeriodicalId":93433,"journal":{"name":"Forces in mechanics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49759609","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-09-11DOI: 10.1016/j.finmec.2023.100237
Anuranjan Kumar, Surajit Kumar Paul
Effect of strain rate on the damage behaviour of hydrogen (H)-charged dual phase (DP 780) steel via the in-situ digital image correlation (DIC) technique is investigated in this work. Since stress concentration sites like notches are common in engineering practice, two types of uniaxial tensile tests have been carried out using smooth and notch tensile specimens for detailed analysis. The study reveals the significance of hydrogen embrittlement in DP 780 steel, as no strain rate effect is observed on the mechanical property in the case of an uncharged smooth tensile specimen. However, a significant effect of strain rate is detected after the H-charging. Hydrogen showed a lesser ability to aid the failure process when the applied strain rate is raised, as it could diffuse over a limited distance during the tensile test. The local axial and width strains, along with necking and fracture strains, are quantified for each specimen to understand the strain rate effect better. A centre-line crack is observed in every H-charged specimen's fracture surface owing to the presence of MnS inclusion in DP steel along the central line and its interaction with the atomic hydrogen. Moreover, the degree of hydrogen embrittlement is substantially higher in the notch tensile specimens than in the smooth ones.
{"title":"Local strain evolution and microstructural characterisation of hydrogen-induced damage at different strain rates in dual phase (DP 780) steel","authors":"Anuranjan Kumar, Surajit Kumar Paul","doi":"10.1016/j.finmec.2023.100237","DOIUrl":"https://doi.org/10.1016/j.finmec.2023.100237","url":null,"abstract":"<div><p>Effect of strain rate on the damage behaviour of hydrogen (H)-charged dual phase (DP 780) steel via the <em>in-situ</em> digital image correlation (DIC) technique is investigated in this work. Since stress concentration sites like notches are common in engineering practice, two types of uniaxial tensile tests have been carried out using smooth and notch tensile specimens for detailed analysis. The study reveals the significance of hydrogen embrittlement in DP 780 steel, as no strain rate effect is observed on the mechanical property in the case of an uncharged smooth tensile specimen. However, a significant effect of strain rate is detected after the H-charging. Hydrogen showed a lesser ability to aid the failure process when the applied strain rate is raised, as it could diffuse over a limited distance during the tensile test. The local axial and width strains, along with necking and fracture strains, are quantified for each specimen to understand the strain rate effect better. A centre-line crack is observed in every H-charged specimen's fracture surface owing to the presence of MnS inclusion in DP steel along the central line and its interaction with the atomic hydrogen. Moreover, the degree of hydrogen embrittlement is substantially higher in the notch tensile specimens than in the smooth ones.</p></div>","PeriodicalId":93433,"journal":{"name":"Forces in mechanics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49752541","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-09-09DOI: 10.1016/j.finmec.2023.100235
Vahid Daghigh , Hamed Edalati , Hamid Daghigh , Davy M. Belk , Kamran Nikbin
Functionally graded materials (FGMs) are high temperature-resistant materials that can simultaneously maintain metallic tenacity and anti-corrosive properties. Nevertheless, using FGMs during a multi-year service life at ultrahigh temperatures is crucial. Hence, the time-dependent creep response of variable-thickness rotating disks made of FGM is investigated. Four different disk profiles of linear, concave, convex, and uniform are considered. The material's creep properties are defined by the Bailey-Norton creep law. Loading is a rotation-based mechanical body force and a uniform temperature throughout the disk. Simultaneous solution of equilibrium, stress-strain, and strain-displacement equations yields a non-homogenous differential equation containing variable and time-dependent coefficients. In an attempt to optimize the computation cost, Bat and Fish algorithms were used to optimize the initial strain presumptions. Semi-analytical solution of this differential equation gives radial and circumferential stress histories and displacement histories. To confirm the solution method, initial thermo-elastic radial stress, and the effective stress history are validated with the existing literature; there is a good agreement between the results. In addition, the finite element software ABAQUS was used to model the FGM disk thermo-elastic behavior, and the result was compared with the semi-analytical solution results. This study emphasizes the significance of accounting for creep effects in the design of FGM rotating disks, as remarkable changes in their displacements and stresses occur over time. This study emphasizes the significance of accounting for creep effects in the design of FGM rotating disks, as notable changes in their displacements and stresses occur over time.
{"title":"Time-dependent creep analysis of ultra-high-temperature functionally graded rotating disks of variable thickness","authors":"Vahid Daghigh , Hamed Edalati , Hamid Daghigh , Davy M. Belk , Kamran Nikbin","doi":"10.1016/j.finmec.2023.100235","DOIUrl":"https://doi.org/10.1016/j.finmec.2023.100235","url":null,"abstract":"<div><p>Functionally graded materials (FGMs) are high temperature-resistant materials that can simultaneously maintain metallic tenacity and anti-corrosive properties. Nevertheless, using FGMs during a multi-year service life at ultrahigh temperatures is crucial. Hence, the time-dependent creep response of variable-thickness rotating disks made of FGM is investigated. Four different disk profiles of linear, concave, convex, and uniform are considered. The material's creep properties are defined by the Bailey-Norton creep law. Loading is a rotation-based mechanical body force and a uniform temperature throughout the disk. Simultaneous solution of equilibrium, stress-strain, and strain-displacement equations yields a non-homogenous differential equation containing variable and time-dependent coefficients. In an attempt to optimize the computation cost, Bat and Fish algorithms were used to optimize the initial strain presumptions. Semi-analytical solution of this differential equation gives radial and circumferential stress histories and displacement histories. To confirm the solution method, initial thermo-elastic radial stress, and the effective stress history are validated with the existing literature; there is a good agreement between the results. In addition, the finite element software ABAQUS was used to model the FGM disk thermo-elastic behavior, and the result was compared with the semi-analytical solution results. This study emphasizes the significance of accounting for creep effects in the design of FGM rotating disks, as remarkable changes in their displacements and stresses occur over time. This study emphasizes the significance of accounting for creep effects in the design of FGM rotating disks, as notable changes in their displacements and stresses occur over time.</p></div>","PeriodicalId":93433,"journal":{"name":"Forces in mechanics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49755576","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-09-09DOI: 10.1016/j.finmec.2023.100236
S. Belodedenko , O. Hrechanyі , T. Vasilchenko , A. Hrechana , Y. Izhevskyi
The developed method of processing experimental data from tests performed according to the four-point asymmetric bending scheme made it possible to establish the coefficient of proportionality between the modes of failure I and II, which for structural steels is in the range of 2,5÷3. The established longevity before the appearance of the critical speed according to the developed models is within the limits of the natural dispersion inherent in fatigue failure, which indicates the effectiveness of the developed algorithm and the correctness of the determined indicators of resistance to failure. The problem of the appearance of an oblique crack during tests on four-point asymmetric bending has been solved. It can be assumed that about 90% of the growth of an oblique crack is caused by the contribution of the mode of failure II.
{"title":"Determination of the critical cyclic fracture toughness for the mode II in mixed fracture of structural steels","authors":"S. Belodedenko , O. Hrechanyі , T. Vasilchenko , A. Hrechana , Y. Izhevskyi","doi":"10.1016/j.finmec.2023.100236","DOIUrl":"https://doi.org/10.1016/j.finmec.2023.100236","url":null,"abstract":"<div><p>The developed method of processing experimental data from tests performed according to the four-point asymmetric bending scheme made it possible to establish the coefficient of proportionality between the modes of failure I and II, which for structural steels is in the range of 2,5÷3<em>.</em> The established longevity before the appearance of the critical speed according to the developed models is within the limits of the natural dispersion inherent in fatigue failure, which indicates the effectiveness of the developed algorithm and the correctness of the determined indicators of resistance to failure. The problem of the appearance of an oblique crack during tests on four-point asymmetric bending has been solved. It can be assumed that about 90% of the growth of an oblique crack is caused by the contribution of the mode of failure II.</p></div>","PeriodicalId":93433,"journal":{"name":"Forces in mechanics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49752359","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-09-06DOI: 10.1016/j.finmec.2023.100233
Luis Espinoza , Jose Antonio Bea , Sourojeet Chakraborty , Daniela Galatro
While several theoretical and experimental studies for cracks in piping exist, most pertain to pipelines, equipment, or fittings under pressure conditions or under stress corrosion conditions at welding. Element finite Method models have occasionally supplemented experimental methods, to investigate such operational fails. In this approach we explore technical options to comprehensively understand crack propagations, by first, evaluating the Stress Intensity Factor using ANSYS Parametric design language then, comparing with the Displacement Correlation Technique, for an elliptical base gas piping (20″APL Gr. B) suffering a longitudinal welding-induced crack, under a compression of 1.86 MPa. The value for an Electric Resistance Welding crack was calculated for the two-dimensional plane, for a quarter-length of propagated crack along the elliptical front. The value estimates are 0.94x MPa from ANSYS Parametric design language vs. 0.7 MPafrom DCT the two methods are close less than 1. These results were compared with the theorical stress intensity factor for elliptical cracks by Broek1 David called elementary engineering fracture mechanics where the values were 0.5x MPa. We found that the proposed FEM method for estimating is the approach that is closest to the theoretical value.
虽然存在一些关于管道裂缝的理论和实验研究,但大多数都是关于管道、设备或配件在压力条件下或焊接时的应力腐蚀条件下的研究。单元有限方法模型偶尔会补充实验方法,以研究这种操作失败。在这种方法中,我们探索了全面理解裂纹扩展的技术选择,首先,使用ANSYS参数化设计语言评估应力强度因子(KI),然后与位移相关技术进行比较,在1.86 MPa的压缩下,对椭圆基燃气管道(20″APL Gr. B)产生纵向焊接裂纹。在二维平面上,计算了沿椭圆前沿延伸1 / 4长度的电阻焊裂纹的kiv值。来自ANSYS参数化设计语言的KI值估计值为0.94x(10)−3 MPam,而来自DCT的KI值估计值为0.70x(10)−2 MPam,两种方法接近小于1。这些结果与Broek1 David(称为初级工程断裂力学)的椭圆裂纹的理论应力强度因子进行了比较,其值为0.5x(10)−1 MPam。我们发现,所提出的估算KI的有限元方法是最接近理论值的方法。
{"title":"Comparison of the stress intensity factor for a longitudinal crack in an elliptical base gas pipe, using FEM vs. DCT methods","authors":"Luis Espinoza , Jose Antonio Bea , Sourojeet Chakraborty , Daniela Galatro","doi":"10.1016/j.finmec.2023.100233","DOIUrl":"10.1016/j.finmec.2023.100233","url":null,"abstract":"<div><p>While several theoretical and experimental studies for cracks in piping exist, most pertain to pipelines, equipment, or fittings under pressure conditions or under stress corrosion conditions at welding. Element finite Method models have occasionally supplemented experimental methods, to investigate such operational fails. In this approach we explore technical options to comprehensively understand crack propagations, by first, evaluating the Stress Intensity Factor <span><math><mrow><mo>(</mo><msub><mi>K</mi><mi>I</mi></msub><mo>)</mo></mrow></math></span> using ANSYS Parametric design language then, comparing with the Displacement Correlation Technique, for an elliptical base gas piping (20″APL Gr. B) suffering a longitudinal welding-induced crack, under a compression of 1.86 MPa. The <span><math><mrow><msub><mi>K</mi><mi>I</mi></msub><mspace></mspace></mrow></math></span>value for an Electric Resistance Welding crack was calculated for the two-dimensional plane, for a quarter-length of propagated crack along the elliptical front. The <span><math><msub><mi>K</mi><mi>I</mi></msub></math></span> value estimates are 0.94x<span><math><msup><mrow><mo>(</mo><mn>10</mn><mo>)</mo></mrow><mrow><mo>−</mo><mn>3</mn></mrow></msup></math></span> MPa<span><math><msqrt><mi>m</mi></msqrt></math></span> from ANSYS Parametric design language vs. 0.7<span><math><mrow><mn>0</mn><mi>x</mi><msup><mrow><mo>(</mo><mn>10</mn><mo>)</mo></mrow><mrow><mo>−</mo><mn>2</mn></mrow></msup></mrow></math></span> MPa<span><math><mrow><msqrt><mi>m</mi></msqrt><mspace></mspace></mrow></math></span>from DCT the two methods are close less than 1. These results were compared with the theorical stress intensity factor for elliptical cracks by Broek<span><sup>1</sup></span> David called elementary engineering fracture mechanics where the values were 0.5x<span><math><msup><mrow><mo>(</mo><mn>10</mn><mo>)</mo></mrow><mrow><mo>−</mo><mn>1</mn></mrow></msup></math></span> MPa<span><math><msqrt><mi>m</mi></msqrt></math></span>. We found that the proposed FEM method for estimating <span><math><mrow><mo>(</mo><msub><mi>K</mi><mi>I</mi></msub><mo>)</mo></mrow></math></span>is the approach that is closest to the theoretical value.</p></div>","PeriodicalId":93433,"journal":{"name":"Forces in mechanics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48174316","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-09-02DOI: 10.1016/j.finmec.2023.100234
Tomoharu Kato , Yoshihiro Sakino , Yuji Sano
Laser peening without coating (LPwC) is a well-known technique to improve high-cycle fatigue properties by introducing compressive residual stress (RS) near the surface of metal components. In this study, X-ray diffraction (XRD) and flexural fatigue tests were applied to pre-cracked 12 mm thick SM490A welding structural steel specimens that were subjected to LPwC nearly 20 years ago with a pulse energy of 200 mJ, a spot diameter of 0.8 mm and a pulse density of 36 pulse/mm2. XRD revealed that the compressive RS has remained stable to date, with approximately 400–500 MPa remaining at the surface and a compressive depth of approximately 0.9 mm from the surface, which is comparable to the data measured by XRD immediately after LPwC. In the flexural fatigue tests with a stress ratio of 0.1 and stress rages of 100, 150 and 200 MPa, LPwC extended the fatigue life by more than 1.6 times, depending on the stress range and individual specimens. Crack restarting cycles were significantly increased by a factor of at least 1.8, and the crack growth rate was suppressed by a factor of about 0.7 or less.
{"title":"Effect of laser peening without coating (LPwC) on retardation of fatigue crack growth in SM490 plates","authors":"Tomoharu Kato , Yoshihiro Sakino , Yuji Sano","doi":"10.1016/j.finmec.2023.100234","DOIUrl":"10.1016/j.finmec.2023.100234","url":null,"abstract":"<div><p>Laser peening without coating (LPwC) is a well-known technique to improve high-cycle fatigue properties by introducing compressive residual stress (RS) near the surface of metal components. In this study, X-ray diffraction (XRD) and flexural fatigue tests were applied to pre-cracked 12 mm thick SM490A welding structural steel specimens that were subjected to LPwC nearly 20 years ago with a pulse energy of 200 mJ, a spot diameter of 0.8 mm and a pulse density of 36 pulse/mm<sup>2</sup>. XRD revealed that the compressive RS has remained stable to date, with approximately 400–500 MPa remaining at the surface and a compressive depth of approximately 0.9 mm from the surface, which is comparable to the data measured by XRD immediately after LPwC. In the flexural fatigue tests with a stress ratio of 0.1 and stress rages of 100, 150 and 200 MPa, LPwC extended the fatigue life by more than 1.6 times, depending on the stress range and individual specimens. Crack restarting cycles were significantly increased by a factor of at least 1.8, and the crack growth rate was suppressed by a factor of about 0.7 or less.</p></div>","PeriodicalId":93433,"journal":{"name":"Forces in mechanics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49493862","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-08-18DOI: 10.1016/j.finmec.2023.100231
Ngoc-Tu Do , Trung Thanh Tran , Trung Nguyen-Thoi , Quoc Hoa Pham
The main goal of this paper is to improve the mixed interpolation of tensorial components triangular (MITC3) by using the edge-based smoothed finite element method (ES-FEM), so-called ES-MITC3, for analyzing the vibration of piezoelectric functionally graded porous (p-FGP) plates subjected to dynamic loading. The material properties of the FGP core vary through thickness with uneven porosity distribution. Besides, the linear relationship between the electric potential and the thickness of the piezoelectric sublayer is taken into account. A closed-loop control algorithm is employed to actively control the vibration of p-FGP plates, through feedback from displacement and velocity. The performance of the proposed method is verified through comparative examples. Finally, the authors hope that the present method can be effectively applied to many smart material models in a multiphysics environment and contribute to understanding texture control by piezoelectric materials through numerical results.
{"title":"An improved MITC3 element for vibration response analysis of piezoelectric functionally graded porous plates","authors":"Ngoc-Tu Do , Trung Thanh Tran , Trung Nguyen-Thoi , Quoc Hoa Pham","doi":"10.1016/j.finmec.2023.100231","DOIUrl":"10.1016/j.finmec.2023.100231","url":null,"abstract":"<div><p>The main goal of this paper is to improve the mixed interpolation of tensorial components triangular (MITC3) by using the edge-based smoothed finite element method (ES-FEM), so-called ES-MITC3, for analyzing the vibration of piezoelectric functionally graded porous (p-FGP) plates subjected to dynamic loading. The material properties of the FGP core vary through thickness with uneven porosity distribution. Besides, the linear relationship between the electric potential and the thickness of the piezoelectric sublayer is taken into account. A closed-loop control algorithm is employed to actively control the vibration of p-FGP plates, through feedback from displacement and velocity. The performance of the proposed method is verified through comparative examples. Finally, the authors hope that the present method can be effectively applied to many smart material models in a multiphysics environment and contribute to understanding texture control by piezoelectric materials through numerical results.</p></div>","PeriodicalId":93433,"journal":{"name":"Forces in mechanics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-08-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48169622","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}