In this paper,the cracking and mechanical responses are studied for the Polymethylmethacrylate(PMMA)sample with two three-dimensional embedded coplanar elliptic flaws subjected to uniaxial compression.The experimental...In this paper,the cracking and mechanical responses are studied for the Polymethylmethacrylate(PMMA)sample with two three-dimensional embedded coplanar elliptic flaws subjected to uniaxial compression.The experimental results indicate that both the peak stress and crack initiation stress first decrease and then increase with increasing flaw angle,and they increase linearly with increasing flaw spacing.Moreover,five crack modes occur in these tested samples,including the coplanar secondary cracks,wing cracks,petal cracks,anti-wing cracks,and vertical giant cracks.The growth length of wing cracks is approximately equal to the length of the long axis of preexisting flaw.However,the maximum width is roughly equal to half the length of the long axis of pre-existing elliptic flaw.The final failure modes include the splitting failure induced by wing cracks and vertical giant cracks,and the mixed tensile-shear failure induced by coplanar secondary cracks and wing cracks.展开更多
The consideration of time dependence is essential for the study of deformation and fracturing processes of rock materials, especially for those subjected to strong compressive and tensile stresses. In this paper, the ...The consideration of time dependence is essential for the study of deformation and fracturing processes of rock materials, especially for those subjected to strong compressive and tensile stresses. In this paper, the self-developed direct tension device and creep testing machine RLW-2000M are used to conduct the creep tests on red sandstone under uniaxial compressive and tensile stresses. The short-term and long-term creep behaviors of rocks under compressive and tensile stresses are investigated, as well as the long-term strength of rocks. It is shown that, under low-stress levels, the creep curve of sandstone consists of decay and steady creep stages; while under high-stress levels, it presents the accelerated creep stage and creep fracture presents characteristics of brittle materials. The relationship between tensile stress and time under uniaxial tension is also put forward. Finally, a nonlinear viscoelastoplastic creep model is used to describe the creep behaviors of rocks under uniaxial compressive and tensile stresses.展开更多
The small punch test technique （SPT） was used to evaluate the mechanical properties of various materials and the basic method to test material tensile mechanics peqeormance from an inverse finite element （ FE） ari...The small punch test technique （SPT） was used to evaluate the mechanical properties of various materials and the basic method to test material tensile mechanics peqeormance from an inverse finite element （ FE） arithmetic with SPT was put forward. The research shows that specific tensile mechanical behavior and strain-stress distribution of each district of weld seam can be accurately determined by small punch test. Therefore, mechanical behavior of the inhomogeneous joint can be predicted by a numerical model. The simulation comes to good agreement with experimental data.展开更多
基金supported by National Natural Science Foundation of China(Grant Nos.51839009,41807251 and 51679017).
文摘In this paper,the cracking and mechanical responses are studied for the Polymethylmethacrylate(PMMA)sample with two three-dimensional embedded coplanar elliptic flaws subjected to uniaxial compression.The experimental results indicate that both the peak stress and crack initiation stress first decrease and then increase with increasing flaw angle,and they increase linearly with increasing flaw spacing.Moreover,five crack modes occur in these tested samples,including the coplanar secondary cracks,wing cracks,petal cracks,anti-wing cracks,and vertical giant cracks.The growth length of wing cracks is approximately equal to the length of the long axis of preexisting flaw.However,the maximum width is roughly equal to half the length of the long axis of pre-existing elliptic flaw.The final failure modes include the splitting failure induced by wing cracks and vertical giant cracks,and the mixed tensile-shear failure induced by coplanar secondary cracks and wing cracks.
基金Supported by the West Region Communication Construction Technology Project of the Ministry of Communications (2009318000001)the National Natural Science Foundation of China (50808187)
文摘The consideration of time dependence is essential for the study of deformation and fracturing processes of rock materials, especially for those subjected to strong compressive and tensile stresses. In this paper, the self-developed direct tension device and creep testing machine RLW-2000M are used to conduct the creep tests on red sandstone under uniaxial compressive and tensile stresses. The short-term and long-term creep behaviors of rocks under compressive and tensile stresses are investigated, as well as the long-term strength of rocks. It is shown that, under low-stress levels, the creep curve of sandstone consists of decay and steady creep stages; while under high-stress levels, it presents the accelerated creep stage and creep fracture presents characteristics of brittle materials. The relationship between tensile stress and time under uniaxial tension is also put forward. Finally, a nonlinear viscoelastoplastic creep model is used to describe the creep behaviors of rocks under uniaxial compressive and tensile stresses.
文摘The small punch test technique （SPT） was used to evaluate the mechanical properties of various materials and the basic method to test material tensile mechanics peqeormance from an inverse finite element （ FE） arithmetic with SPT was put forward. The research shows that specific tensile mechanical behavior and strain-stress distribution of each district of weld seam can be accurately determined by small punch test. Therefore, mechanical behavior of the inhomogeneous joint can be predicted by a numerical model. The simulation comes to good agreement with experimental data.
