The mechanical properties of fractured rock mass have an important influence on the safety and stability of underground engineering. Grouting is a common way to reinforce fractured rock mass. The uniaxial compression tests of red sandstone specimens with different prefabricated crack inclination angles before and after grouting were carried out. Based on the load-deformation data and synchronous image acquisition, the mechanical properties, crack propagation law and failure mode of the specimens before and after grouting were studied. The results show that the peak strength and elastic modulus of the ungrouted specimen increase with the increase of the inclination angle of the prefabricated crack. Compared with the ungrouted specimen, grouting can significantly improve the peak strength and elastic modulus of the specimen. The cracks of the ungrouted specimen mainly initiate from the tip of the prefabricated crack, and the cracks of the grouting specimen mainly initiate from the upper and lower surfaces of the specimen and the far field. Based on the macroscopic and microscopic damage theory, the constitutive model of grouting rock mass is proposed. By comparing with the experimental data, the rationality of the constitutive model is verified.
{"title":"Experimental and theoretical model study on grouting reinforcement effect of fractured rock mass","authors":"Hui Wang, Hairong Yu, Xiaotong Zhang, Hongyu Zhuo, Jitao Jia, Haosong Wang, Hongyuan Huai","doi":"10.1177/10567895241297699","DOIUrl":"https://doi.org/10.1177/10567895241297699","url":null,"abstract":"The mechanical properties of fractured rock mass have an important influence on the safety and stability of underground engineering. Grouting is a common way to reinforce fractured rock mass. The uniaxial compression tests of red sandstone specimens with different prefabricated crack inclination angles before and after grouting were carried out. Based on the load-deformation data and synchronous image acquisition, the mechanical properties, crack propagation law and failure mode of the specimens before and after grouting were studied. The results show that the peak strength and elastic modulus of the ungrouted specimen increase with the increase of the inclination angle of the prefabricated crack. Compared with the ungrouted specimen, grouting can significantly improve the peak strength and elastic modulus of the specimen. The cracks of the ungrouted specimen mainly initiate from the tip of the prefabricated crack, and the cracks of the grouting specimen mainly initiate from the upper and lower surfaces of the specimen and the far field. Based on the macroscopic and microscopic damage theory, the constitutive model of grouting rock mass is proposed. By comparing with the experimental data, the rationality of the constitutive model is verified.","PeriodicalId":13837,"journal":{"name":"International Journal of Damage Mechanics","volume":"35 1","pages":""},"PeriodicalIF":4.2,"publicationDate":"2024-11-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142598142","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-31DOI: 10.1177/10567895241292744
Tianhong Yu, Wenxuan Qi, Elena Sitnikova, Shuguang Li
A novel damage evolution model for unidirectional (UD) composites is established in this paper in the context of continuum damage mechanics (CDM). It addresses matrix cracking and it is to be applied along with the damage representation established previously. The concept of damage driving force is employed based on the Helmholtz free energy. It is shown that the damage driving force can be partitioned into three parts, resembling closely three conventional modes of fracture, respectively. A damage evolution law is derived accordingly based on the newly obtained expressions of the damage driving force. The fully rationalised Tsai-Wu criterion is employed in the model for predicting the initiation of matrix cracking damage and fibre failure, assisted with the rationalised maximum stress criterion for identifying the damage modes. A mechanism is introduced to describe the unloading behaviour as a part of the proposed model. The predictions were validated against experimental results, showing good agreement with the experiments and demonstrating the capability and effectiveness of the proposed model.
{"title":"A novel continuum damage evolution model based on the concept of damage driving force for unidirectional composites","authors":"Tianhong Yu, Wenxuan Qi, Elena Sitnikova, Shuguang Li","doi":"10.1177/10567895241292744","DOIUrl":"https://doi.org/10.1177/10567895241292744","url":null,"abstract":"A novel damage evolution model for unidirectional (UD) composites is established in this paper in the context of continuum damage mechanics (CDM). It addresses matrix cracking and it is to be applied along with the damage representation established previously. The concept of damage driving force is employed based on the Helmholtz free energy. It is shown that the damage driving force can be partitioned into three parts, resembling closely three conventional modes of fracture, respectively. A damage evolution law is derived accordingly based on the newly obtained expressions of the damage driving force. The fully rationalised Tsai-Wu criterion is employed in the model for predicting the initiation of matrix cracking damage and fibre failure, assisted with the rationalised maximum stress criterion for identifying the damage modes. A mechanism is introduced to describe the unloading behaviour as a part of the proposed model. The predictions were validated against experimental results, showing good agreement with the experiments and demonstrating the capability and effectiveness of the proposed model.","PeriodicalId":13837,"journal":{"name":"International Journal of Damage Mechanics","volume":"48 1","pages":""},"PeriodicalIF":4.2,"publicationDate":"2024-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142561879","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-25DOI: 10.1177/10567895241292763
Liu Jin, Bo Lu, Wenxuan Yu, Xiuli Du
This paper applied a thermal-mechanical sequential coupled mesoscopic simulation method to explore the axial compression performance and the corresponding size effect of Reinforced Concrete Columns confined by Stirrups (i.e., RCCS) at low temperatures, with considering the interaction between concrete meso-components and steel bars as well as the low-temperature effect of mechanical parameters. Based on the heat conduction analysis, the axial compression mechanical failure behavior of RCCS with four structural sizes (i.e., 267 × 267 × 801, 400 × 400 × 1200, 600 × 600 × 1800 and 800 × 800 × 2400 mm) and two stirrup ratios (i.e., 1.26% and 2.89%) at different temperatures (i.e., T = 20, −30, −60 and −90°C) was subsequently simulated. The effects of temperature, structural size and volume stirrup ratio on axial compression properties were quantitatively discussed. The results showed that the peak strength of RCCS increased with the decreasing temperature, and the smaller-sized RCCS showed a stronger effect of low-temperature enhancement. Both the residual strength and displacement ductility coefficient decreased with the decreasing temperature. The peak strength, residual strength and displacement ductility coefficient of RCCS decreased with the increasing structural size, showing obvious size effects. The size effect on peak strength increased with the decreasing temperature, (the maximum increase was nearly 140%), but the size effect on displacement ductility coefficient decreased (the maximum decrease was nearly 70%). The peak strength, residual strength and ductility were enhanced with the increasing volume stirrup ratio, which was helpful to reduce the influence of size effect. Finally, an improved size effect theoretical model was proposed, which can effectively predict the axial compressive strength of RCCS with different structural sizes and stirrup ratios at room and low temperatures. The present research results can provide reference for the large-scale engineering application of RCCS in low-temperature environments.
{"title":"Size effect modellings of axial compressive failure of RC columns at low temperatures","authors":"Liu Jin, Bo Lu, Wenxuan Yu, Xiuli Du","doi":"10.1177/10567895241292763","DOIUrl":"https://doi.org/10.1177/10567895241292763","url":null,"abstract":"This paper applied a thermal-mechanical sequential coupled mesoscopic simulation method to explore the axial compression performance and the corresponding size effect of Reinforced Concrete Columns confined by Stirrups (i.e., RCCS) at low temperatures, with considering the interaction between concrete meso-components and steel bars as well as the low-temperature effect of mechanical parameters. Based on the heat conduction analysis, the axial compression mechanical failure behavior of RCCS with four structural sizes (i.e., 267 × 267 × 801, 400 × 400 × 1200, 600 × 600 × 1800 and 800 × 800 × 2400 mm) and two stirrup ratios (i.e., 1.26% and 2.89%) at different temperatures (i.e., T = 20, −30, −60 and −90°C) was subsequently simulated. The effects of temperature, structural size and volume stirrup ratio on axial compression properties were quantitatively discussed. The results showed that the peak strength of RCCS increased with the decreasing temperature, and the smaller-sized RCCS showed a stronger effect of low-temperature enhancement. Both the residual strength and displacement ductility coefficient decreased with the decreasing temperature. The peak strength, residual strength and displacement ductility coefficient of RCCS decreased with the increasing structural size, showing obvious size effects. The size effect on peak strength increased with the decreasing temperature, (the maximum increase was nearly 140%), but the size effect on displacement ductility coefficient decreased (the maximum decrease was nearly 70%). The peak strength, residual strength and ductility were enhanced with the increasing volume stirrup ratio, which was helpful to reduce the influence of size effect. Finally, an improved size effect theoretical model was proposed, which can effectively predict the axial compressive strength of RCCS with different structural sizes and stirrup ratios at room and low temperatures. The present research results can provide reference for the large-scale engineering application of RCCS in low-temperature environments.","PeriodicalId":13837,"journal":{"name":"International Journal of Damage Mechanics","volume":"1 1","pages":""},"PeriodicalIF":4.2,"publicationDate":"2024-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142490647","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-22DOI: 10.1177/10567895241292748
Lubo Meng, Shan Zhang, Tianbin Li, Tianyi Liu, Haoyu Li
The failure of layered rock after high temperature exposure is a major concern in deep underground engineering projects. This paper proposes an improved Nishihara creep constitutive model that considers damage factors and the bedding angle, which overcomes the shortcomings of the deviation in the description of the conventional Nishihara model in the acceleration stage. The constitutive model is verified by the conventional triaxial creepiest. The theoretical curve has a high degree of fitting with the experimental curve. The experimental results show that a temperature of [Formula: see text] has an obvious influence on the steady creep rate and the creep strain of layered sandstone, and [Formula: see text] can be regarded as the temperature threshold for the long-term strength and change from anisotropic to isotropic of layered sandstone. The irreversible melting mixing phenomenon at the boundary of mineral particles with increasing temperature is the mechanism by which different treatment temperatures affect the anisotropy degree of layered rock.
{"title":"Study on the creep constitutive model of layered rockconsidering anisotropic and damage factors after hightemperature exposure","authors":"Lubo Meng, Shan Zhang, Tianbin Li, Tianyi Liu, Haoyu Li","doi":"10.1177/10567895241292748","DOIUrl":"https://doi.org/10.1177/10567895241292748","url":null,"abstract":"The failure of layered rock after high temperature exposure is a major concern in deep underground engineering projects. This paper proposes an improved Nishihara creep constitutive model that considers damage factors and the bedding angle, which overcomes the shortcomings of the deviation in the description of the conventional Nishihara model in the acceleration stage. The constitutive model is verified by the conventional triaxial creepiest. The theoretical curve has a high degree of fitting with the experimental curve. The experimental results show that a temperature of [Formula: see text] has an obvious influence on the steady creep rate and the creep strain of layered sandstone, and [Formula: see text] can be regarded as the temperature threshold for the long-term strength and change from anisotropic to isotropic of layered sandstone. The irreversible melting mixing phenomenon at the boundary of mineral particles with increasing temperature is the mechanism by which different treatment temperatures affect the anisotropy degree of layered rock.","PeriodicalId":13837,"journal":{"name":"International Journal of Damage Mechanics","volume":"8 1","pages":""},"PeriodicalIF":4.2,"publicationDate":"2024-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142487450","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-21DOI: 10.1177/10567895241292750
Yuezong Yang, Zhushan Shao, Nannan Zhao, Kui Wu
The deterioration of rock material properties induced by seepage pressure is a serious danger to the stability of geotechnical engineering. The formation and propagation of microcracks is the primary cause of rock macro failure. This work proposes an damage-based analytical model to assess the impact of seepage pressure on the macro mechanical behaviors of rocks from the standpoint of micro fracture. A wing crack model serves as the foundation for the analytical model. This model has taken into account the impact of seepage pressure on the initiation and growth of wing cracks. The constitutive relation is constructed based on the equivalency connection of damage defined by strain and wing crack length. A comparison between the analytical results and the reported experimental data confirms the reasonableness of the analytical model. Investigations are conducted on the relationship between the macro mechanical behavior of rocks and micro fracture under various seepage pressures, confining pressures, and microscopic parameters. The findings demonstrate that the cracks growth is initially steady before becoming unstable. The growing process of wing cracks stops when they connect with one another, and friction between the crack surfaces takes over. The initiation and growth of wing cracks may be aided by the seepage pressure. As the wing crack propagates, the seepage pressure effect initially increases, then decreases, and eventually has practically no impact. The influence of seepage pressure on rock macro mechanical behavior is that with seepage pressure increasing, the initiation stress and peak stress decrease, but the residual stress is basically a constant. The rock micro fracture process is significantly influenced by confining pressures and microscopic factors, which in turn affect the macro mechanical behavior. The study’s findings offer a micro fracture foundation for comprehending how seepage pressure affects the macro mechanical behaviors of rocks.
{"title":"A damage-based analytical model to evaluate seepage pressure effect on rock macro mechanical behaviors from the perspective of micro-fracture","authors":"Yuezong Yang, Zhushan Shao, Nannan Zhao, Kui Wu","doi":"10.1177/10567895241292750","DOIUrl":"https://doi.org/10.1177/10567895241292750","url":null,"abstract":"The deterioration of rock material properties induced by seepage pressure is a serious danger to the stability of geotechnical engineering. The formation and propagation of microcracks is the primary cause of rock macro failure. This work proposes an damage-based analytical model to assess the impact of seepage pressure on the macro mechanical behaviors of rocks from the standpoint of micro fracture. A wing crack model serves as the foundation for the analytical model. This model has taken into account the impact of seepage pressure on the initiation and growth of wing cracks. The constitutive relation is constructed based on the equivalency connection of damage defined by strain and wing crack length. A comparison between the analytical results and the reported experimental data confirms the reasonableness of the analytical model. Investigations are conducted on the relationship between the macro mechanical behavior of rocks and micro fracture under various seepage pressures, confining pressures, and microscopic parameters. The findings demonstrate that the cracks growth is initially steady before becoming unstable. The growing process of wing cracks stops when they connect with one another, and friction between the crack surfaces takes over. The initiation and growth of wing cracks may be aided by the seepage pressure. As the wing crack propagates, the seepage pressure effect initially increases, then decreases, and eventually has practically no impact. The influence of seepage pressure on rock macro mechanical behavior is that with seepage pressure increasing, the initiation stress and peak stress decrease, but the residual stress is basically a constant. The rock micro fracture process is significantly influenced by confining pressures and microscopic factors, which in turn affect the macro mechanical behavior. The study’s findings offer a micro fracture foundation for comprehending how seepage pressure affects the macro mechanical behaviors of rocks.","PeriodicalId":13837,"journal":{"name":"International Journal of Damage Mechanics","volume":"86 1","pages":""},"PeriodicalIF":4.2,"publicationDate":"2024-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142486812","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-17DOI: 10.1177/10567895241292749
Yuan Fang, Xu Yazhou
Fretting fatigue often occurs in the interfaces between components, subjected to complex multi-axial load states and high stress gradients at the contact edge region. For the prediction of fretting fatigue crack initiation and in-depth understanding of the crack initiation mechanism, it is essential to investigate the damage mechanisms across various scales and explore the underlying scale coupling mechanisms. By introducing a power-law based scale coupling relationship, a two-scale model of fretting fatigue crack initiation life is proposed by combining macroscopic continuum damage mechanics (CDM) with microscopic crystal plastic finite element method (CPFEM). The simulation results indicate that the predicted fretting fatigue initiation life shows better accuracy than the result predicted by single-scale CDM model. In case of low stress level the rate of accumulated dissipation energy can be clearly divided into two stages with turning points, whereas it exhibits a relatively uniform damage process under high stress level. Moreover, the proposed two-scale model partly provides physical explanation for fretting fatigue crack initiation based on the information from the microscale.
{"title":"Accumulated crystal plasticity dissipation energy driven continuum damage two-scale model for fretting fatigue initiation life","authors":"Yuan Fang, Xu Yazhou","doi":"10.1177/10567895241292749","DOIUrl":"https://doi.org/10.1177/10567895241292749","url":null,"abstract":"Fretting fatigue often occurs in the interfaces between components, subjected to complex multi-axial load states and high stress gradients at the contact edge region. For the prediction of fretting fatigue crack initiation and in-depth understanding of the crack initiation mechanism, it is essential to investigate the damage mechanisms across various scales and explore the underlying scale coupling mechanisms. By introducing a power-law based scale coupling relationship, a two-scale model of fretting fatigue crack initiation life is proposed by combining macroscopic continuum damage mechanics (CDM) with microscopic crystal plastic finite element method (CPFEM). The simulation results indicate that the predicted fretting fatigue initiation life shows better accuracy than the result predicted by single-scale CDM model. In case of low stress level the rate of accumulated dissipation energy can be clearly divided into two stages with turning points, whereas it exhibits a relatively uniform damage process under high stress level. Moreover, the proposed two-scale model partly provides physical explanation for fretting fatigue crack initiation based on the information from the microscale.","PeriodicalId":13837,"journal":{"name":"International Journal of Damage Mechanics","volume":"25 1","pages":""},"PeriodicalIF":4.2,"publicationDate":"2024-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142448782","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-30DOI: 10.1177/10567895241277657
Hui Wang, Zhichao Xu, Hongyuan Huai, Yunteng Yin, Jiacong Zeng, Zhihao Du, Hang Zhou
In order to study the effects of crack inclination angle and loading rate on rock mechanical properties, creep characteristics, and failure characteristics. Taking homogeneous red sandstone with different fracture angles as the research object, uniaxial compression tests and uniaxial compression creep tests were conducted at different loading rates. The results showed that under the same fracture angle, the loading rate was positively correlated with the peak strength, elastic modulus, instantaneous strain, creep strain, and steady-state creep rate of the sample, while negatively correlated with the peak strain. At the same loading rate, the mechanical properties and creep properties of the sample were controlled by the crack inclination angle α. With the increase of α, the peak strength, peak strain, instantaneous strain, creep strain and steady-state creep rate decreased first and then increased, and the elastic modulus increased. On the basis of rock creep testing, it is also important to establish a creep model that conforms to the actual test situation for studying rock creep characteristics. However, many models currently used cannot accurately describe the three stages of rock creep, especially the accelerated creep stage. Therefore, based on Burgers elements, this paper introduces plastic damage bodies based on damage rates and software components based on fractional calculus, A new creep model was obtained and its rationality was verified through experimental results. The results showed that the fit between the model and experimental data was above 0.97, indicating that the model can better describe the three stages of rock creep, especially reflecting the non-linear characteristics of the accelerated creep stage.
{"title":"Experimental study on the mechanical properties of red sandstone with fractures under different loading rates","authors":"Hui Wang, Zhichao Xu, Hongyuan Huai, Yunteng Yin, Jiacong Zeng, Zhihao Du, Hang Zhou","doi":"10.1177/10567895241277657","DOIUrl":"https://doi.org/10.1177/10567895241277657","url":null,"abstract":"In order to study the effects of crack inclination angle and loading rate on rock mechanical properties, creep characteristics, and failure characteristics. Taking homogeneous red sandstone with different fracture angles as the research object, uniaxial compression tests and uniaxial compression creep tests were conducted at different loading rates. The results showed that under the same fracture angle, the loading rate was positively correlated with the peak strength, elastic modulus, instantaneous strain, creep strain, and steady-state creep rate of the sample, while negatively correlated with the peak strain. At the same loading rate, the mechanical properties and creep properties of the sample were controlled by the crack inclination angle α. With the increase of α, the peak strength, peak strain, instantaneous strain, creep strain and steady-state creep rate decreased first and then increased, and the elastic modulus increased. On the basis of rock creep testing, it is also important to establish a creep model that conforms to the actual test situation for studying rock creep characteristics. However, many models currently used cannot accurately describe the three stages of rock creep, especially the accelerated creep stage. Therefore, based on Burgers elements, this paper introduces plastic damage bodies based on damage rates and software components based on fractional calculus, A new creep model was obtained and its rationality was verified through experimental results. The results showed that the fit between the model and experimental data was above 0.97, indicating that the model can better describe the three stages of rock creep, especially reflecting the non-linear characteristics of the accelerated creep stage.","PeriodicalId":13837,"journal":{"name":"International Journal of Damage Mechanics","volume":"121 1","pages":""},"PeriodicalIF":4.2,"publicationDate":"2024-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142360550","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-27DOI: 10.1177/10567895241282229
Abel Cherouat, Thierry Barriere, Hong Wang
In this study, a comprehensive investigation was conducted to explore the material extrusion process of NiTi shape-memory alloy-based bio-composite polymeric matrix. Polylactic acid PLA+ Stearic Acid polymeric matrix are performed in order to develop an environmentally friendly process for manufacturing feedstocks with [Formula: see text] nickel-titanium powders for employed in the 3D printing process. The additive manufacturing process based on the extrusion of materials will be studied at all stages (feedstock manufacturing with nickel-titanium powders, 3D printing of bio-composite green part, thermal debinding, and densification by solid-state diffusion) using experimental approaches, analytical approaches to predict printability index and thermo-physical analyses for the formulation of NiTi and biocomposite binders. Printing parameters were optimized by analysing the microstructure, rheological, mechanical properties of feedstock and 3D printed parts. Static mechanical tests will be performed in association with numerical modelling to study the evolution of damage for fully densified SMA specimens in order to describe the ductile failure of 3D printed specimens. Micromechanical phenomenological constitutive models are used in Finite Element software and which can account for the damage localization, initiation and damage growth based on continuum damage mechanics. The results of this study can be used to optimize the extrusion process parameters for different materials and can be helpful for researchers and industrialists to further explore and develop sustainable and eco-friendly materials.
本研究对基于镍钛形状记忆合金的生物复合聚合物基体的材料挤压工艺进行了全面调查。聚乳酸 PLA+ 硬脂酸聚合基体，以开发出一种环保型工艺，用于制造含有[配方：见正文]镍钛粉末的原料，并将其应用于三维打印工艺中。将利用实验方法、预测可打印性指数的分析方法以及镍钛和生物复合材料粘合剂配方的热物理分析方法，研究基于材料挤压的添加制造工艺的各个阶段（镍钛粉末原料制造、生物复合材料绿色部件的三维打印、热脱粘和固态扩散致密化）。通过分析原料和三维打印部件的微观结构、流变学和机械性能，对打印参数进行了优化。静态机械测试将与数值建模相结合，研究全致密 SMA 试样的损伤演变，以描述 3D 打印试样的韧性破坏。有限元软件中使用了微观机械现象学构成模型，该模型可在连续损伤力学的基础上解释损伤定位、起始和损伤增长。本研究的结果可用于优化不同材料的挤压工艺参数，并有助于研究人员和工业家进一步探索和开发可持续的环保材料。
{"title":"Experimental analysis of extrusion-based additive manufacturing process of bio-composite NiTi alloy","authors":"Abel Cherouat, Thierry Barriere, Hong Wang","doi":"10.1177/10567895241282229","DOIUrl":"https://doi.org/10.1177/10567895241282229","url":null,"abstract":"In this study, a comprehensive investigation was conducted to explore the material extrusion process of NiTi shape-memory alloy-based bio-composite polymeric matrix. Polylactic acid PLA+ Stearic Acid polymeric matrix are performed in order to develop an environmentally friendly process for manufacturing feedstocks with [Formula: see text] nickel-titanium powders for employed in the 3D printing process. The additive manufacturing process based on the extrusion of materials will be studied at all stages (feedstock manufacturing with nickel-titanium powders, 3D printing of bio-composite green part, thermal debinding, and densification by solid-state diffusion) using experimental approaches, analytical approaches to predict printability index and thermo-physical analyses for the formulation of NiTi and biocomposite binders. Printing parameters were optimized by analysing the microstructure, rheological, mechanical properties of feedstock and 3D printed parts. Static mechanical tests will be performed in association with numerical modelling to study the evolution of damage for fully densified SMA specimens in order to describe the ductile failure of 3D printed specimens. Micromechanical phenomenological constitutive models are used in Finite Element software and which can account for the damage localization, initiation and damage growth based on continuum damage mechanics. The results of this study can be used to optimize the extrusion process parameters for different materials and can be helpful for researchers and industrialists to further explore and develop sustainable and eco-friendly materials.","PeriodicalId":13837,"journal":{"name":"International Journal of Damage Mechanics","volume":"56 1","pages":""},"PeriodicalIF":4.2,"publicationDate":"2024-09-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142328701","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-24DOI: 10.1177/10567895241279842
A Goumghar, K Azouaoui, M Assarar, W Zouari, S Mouhoubi, R Ayad, A El Mahi
The aim of this study is to investigate the fatigue behaviour of hybrid flax-glass/epoxy composites under repeated impact loading subsequent to water ageing. Different plates of these composite materials were fabricated using the vacuum infusion technique. Five stacking sequences were considered: [F8], [G/F3]S, [G2/F2]S, [G3/F]S, and [G8], where F and G stand for flax/epoxy and glass/epoxy plies, respectively. Water ageing was conducted by immersing the composite specimens in tap water at room temperature for various durations, and until saturation was reached. Fatigue impact tests were carried out using three impact energies: 3, 4, and 5 J. An advanced high-resolution camera was used to monitor the evolution of damage mechanisms occurring on the non-impacted surfaces, while a laser thermometer was considered to track the temperature variations within each composite specimen. The obtained results show that flax-glass hybridization reduces the mass of absorbed water in flax/epoxy composite by up to 70%. Furthermore, there is a more pronounced decrease in longitudinal modulus and maximum stress in aged composites, with reductions of up to 70% compared to unaged ones. Additionally, visible damage occurs even at low energy levels, manifesting from the initial impacts in both aged and unaged composite laminates. Moreover, a correlation between the number of impacts to failure and the cumulative energy is revealed. Ultimately, water aging reduces the strength of the studied composite laminates and their resistance to impact fatigue. Furthermore, the hybrid laminates with high proportion of flax layers are particularly susceptible to water ageing effects.
本研究的目的是调查亚麻-玻璃-环氧混合复合材料在水老化后反复冲击加载下的疲劳行为。采用真空灌注技术制造了这些复合材料的不同板材。考虑了五种堆叠序列：[F8]、[G/F3]S、[G2/F2]S、[G3/F]S 和 [G8]，其中 F 和 G 分别代表亚麻/环氧层和玻璃/环氧层。水老化是将复合材料试样浸泡在室温下的自来水中，浸泡时间长短不一，直至达到饱和状态。疲劳冲击试验采用三种冲击能量进行：先进的高分辨率照相机用于监控非撞击表面的损伤机制演变，而激光温度计则用于跟踪每个复合材料试样内部的温度变化。研究结果表明，亚麻-玻璃杂化使亚麻/环氧复合材料的吸水率降低了 70%。此外，在老化的复合材料中，纵向模量和最大应力的下降更为明显，与未老化的复合材料相比，降幅高达 70%。此外，即使在低能量水平下，老化和未老化的复合材料层压板也会从最初的冲击开始出现明显的损坏。此外，还发现了冲击到破坏的次数与累积能量之间的相关性。最终，水老化降低了所研究的复合材料层压板的强度及其抗冲击疲劳的能力。此外，亚麻层比例较高的混合层压板尤其容易受到水老化效应的影响。
{"title":"Damage investigation of hybrid flax-glass/epoxy composites subjected to impact fatigue under water ageing","authors":"A Goumghar, K Azouaoui, M Assarar, W Zouari, S Mouhoubi, R Ayad, A El Mahi","doi":"10.1177/10567895241279842","DOIUrl":"https://doi.org/10.1177/10567895241279842","url":null,"abstract":"The aim of this study is to investigate the fatigue behaviour of hybrid flax-glass/epoxy composites under repeated impact loading subsequent to water ageing. Different plates of these composite materials were fabricated using the vacuum infusion technique. Five stacking sequences were considered: [F<jats:sub>8</jats:sub>], [G/F<jats:sub>3</jats:sub>]<jats:sub>S</jats:sub>, [G<jats:sub>2</jats:sub>/F<jats:sub>2</jats:sub>]<jats:sub>S</jats:sub>, [G<jats:sub>3</jats:sub>/F]<jats:sub>S</jats:sub>, and [G<jats:sub>8</jats:sub>], where F and G stand for flax/epoxy and glass/epoxy plies, respectively. Water ageing was conducted by immersing the composite specimens in tap water at room temperature for various durations, and until saturation was reached. Fatigue impact tests were carried out using three impact energies: 3, 4, and 5 J. An advanced high-resolution camera was used to monitor the evolution of damage mechanisms occurring on the non-impacted surfaces, while a laser thermometer was considered to track the temperature variations within each composite specimen. The obtained results show that flax-glass hybridization reduces the mass of absorbed water in flax/epoxy composite by up to 70%. Furthermore, there is a more pronounced decrease in longitudinal modulus and maximum stress in aged composites, with reductions of up to 70% compared to unaged ones. Additionally, visible damage occurs even at low energy levels, manifesting from the initial impacts in both aged and unaged composite laminates. Moreover, a correlation between the number of impacts to failure and the cumulative energy is revealed. Ultimately, water aging reduces the strength of the studied composite laminates and their resistance to impact fatigue. Furthermore, the hybrid laminates with high proportion of flax layers are particularly susceptible to water ageing effects.","PeriodicalId":13837,"journal":{"name":"International Journal of Damage Mechanics","volume":"2 1","pages":""},"PeriodicalIF":4.2,"publicationDate":"2024-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142317537","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-24DOI: 10.1177/10567895241280788
Lorenzo Pagliari, Franco Concli
Most of real-world structural components that undergo cyclic loading feature multiaxial fatigue. When the cyclic loading involves also significant plastic deformation, multiaxial low-cycle fatigue takes place. Applications where multiaxial low-cycle fatigue can be observed very often involve metal components. To predict their lives multiple criteria and models have been proposed, but their development has not followed a regular path. Multiple reviews are available in literature. However, many of them are outdated, they often employ different classification methods to categorize available criteria, many focus on specific families of criteria, and others do not include sufficient theoretical background. Moreover, none of the available reviews is based on a systematic literature search method. As a result, approaching the topic can result arduous and chaotic, especially for first timers. This work aims at providing a clear, comprehensive, and definitive review of available criteria for multiaxial low-cycle fatigue. First, the basic theoretical background is explained. Secondly, a systematic approach is described and employed to identify all major currently available criteria. Then, they are classified and commentary about different classification styles that can be found in literature is added. Eventually they are described, together with their latest proposed variations. In this way this review can be employed as a guiding reference, especially for engineers approaching the topic for the first time.
{"title":"A review of multiaxial low-cycle fatigue criteria for life prediction of metals","authors":"Lorenzo Pagliari, Franco Concli","doi":"10.1177/10567895241280788","DOIUrl":"https://doi.org/10.1177/10567895241280788","url":null,"abstract":"Most of real-world structural components that undergo cyclic loading feature multiaxial fatigue. When the cyclic loading involves also significant plastic deformation, multiaxial low-cycle fatigue takes place. Applications where multiaxial low-cycle fatigue can be observed very often involve metal components. To predict their lives multiple criteria and models have been proposed, but their development has not followed a regular path. Multiple reviews are available in literature. However, many of them are outdated, they often employ different classification methods to categorize available criteria, many focus on specific families of criteria, and others do not include sufficient theoretical background. Moreover, none of the available reviews is based on a systematic literature search method. As a result, approaching the topic can result arduous and chaotic, especially for first timers. This work aims at providing a clear, comprehensive, and definitive review of available criteria for multiaxial low-cycle fatigue. First, the basic theoretical background is explained. Secondly, a systematic approach is described and employed to identify all major currently available criteria. Then, they are classified and commentary about different classification styles that can be found in literature is added. Eventually they are described, together with their latest proposed variations. In this way this review can be employed as a guiding reference, especially for engineers approaching the topic for the first time.","PeriodicalId":13837,"journal":{"name":"International Journal of Damage Mechanics","volume":"216 1","pages":""},"PeriodicalIF":4.2,"publicationDate":"2024-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142317545","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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