The flatwise tension(FWT) and single leg bending(SLB) tests were used to investigate the fracture behavior of honeycomb sandwich specimens.In the FWT test,only the interlaminar delamination was observed.The test resul...The flatwise tension(FWT) and single leg bending(SLB) tests were used to investigate the fracture behavior of honeycomb sandwich specimens.In the FWT test,only the interlaminar delamination was observed.The test results show that the interfacial peel strength is higher than the interlaminar peel strength.In terms of SLB experiment,a new fracture mode was found,namely IKP(initiation of interlaminar delamination,kinking into facesheet and propagation of interlaminar delamination).The virtual crack closure technique was applied to separate the values of Mode I and Mode II components of the strain energy release rate in SLB experiment.The finite element analysis result shows that the Mode I strain energy release rate is higher than the Mode II strain energy release rate.To simulate the failure of SLB test of honeycomb sandwich specimens,a new computational model based on the Tsai-Hill failure criterion and the cohesive zone model is proposed.In comparison with experimental results,it can be concluded that the computational model can validly simulate the IKP of a honeycomb sandwich structures with reasonable accuracy.展开更多
A series of tests was performed with three-point single-edge-notched-bend (SENB) specimens in a condenser material (Titanium alloy). Results show that the J-integral values of welded joint and HAZ are obviously smalle...A series of tests was performed with three-point single-edge-notched-bend (SENB) specimens in a condenser material (Titanium alloy). Results show that the J-integral values of welded joint and HAZ are obviously smaller than those of the base metal. It signifies that the welding process can result in a reduced toughness of Titanium alloy and the effect of crack orientation on toughness value is not negligible for engineering applications. Besides, the J-integral values of L-T direction specimens are much higher than those of L-S ones. The J-integral values of rolled ring are:JC-R>JC-L>JL-R.展开更多
A recent joint paper with Doina Cioranescu and Julia Orlik was concerned with the homogenization of a linearized elasticity problem with inclusions and cracks(see[Cioranescu, D., Damlamian, A. and Orlik, J., Homogeniz...A recent joint paper with Doina Cioranescu and Julia Orlik was concerned with the homogenization of a linearized elasticity problem with inclusions and cracks(see[Cioranescu, D., Damlamian, A. and Orlik, J., Homogenization via unfolding in periodic elasticity with contact on closed and open cracks, Asymptotic Analysis, 82, 2013, 201–232]). It required uniform estimates with respect to the homogenization parameter. A Korn inequality was used which involves unilateral terms on the boundaries where a nopenetration condition is imposed. In this paper, the author presents a general method to obtain many diverse Korn inequalities including the unilateral inequalities used in [Cioranescu, D., Damlamian, A. and Orlik, J., Homogenization via unfolding in periodic elasticity with contact on closed and open cracks, Asymptotic Analysis, 82, 2013, 201–232]. A preliminary version was presented in [Damlamian, A., Some unilateral Korn inequalities with application to a contact problem with inclusions, C. R. Acad. Sci. Paris, Ser. I,350, 2012, 861–865].展开更多
基金Sponsored by the Heilongjiang Postdoctoral Grant and the National Science Foundation for Post-doctoral Scientists of China (Grant No.20080440887)
文摘The flatwise tension(FWT) and single leg bending(SLB) tests were used to investigate the fracture behavior of honeycomb sandwich specimens.In the FWT test,only the interlaminar delamination was observed.The test results show that the interfacial peel strength is higher than the interlaminar peel strength.In terms of SLB experiment,a new fracture mode was found,namely IKP(initiation of interlaminar delamination,kinking into facesheet and propagation of interlaminar delamination).The virtual crack closure technique was applied to separate the values of Mode I and Mode II components of the strain energy release rate in SLB experiment.The finite element analysis result shows that the Mode I strain energy release rate is higher than the Mode II strain energy release rate.To simulate the failure of SLB test of honeycomb sandwich specimens,a new computational model based on the Tsai-Hill failure criterion and the cohesive zone model is proposed.In comparison with experimental results,it can be concluded that the computational model can validly simulate the IKP of a honeycomb sandwich structures with reasonable accuracy.
文摘A series of tests was performed with three-point single-edge-notched-bend (SENB) specimens in a condenser material (Titanium alloy). Results show that the J-integral values of welded joint and HAZ are obviously smaller than those of the base metal. It signifies that the welding process can result in a reduced toughness of Titanium alloy and the effect of crack orientation on toughness value is not negligible for engineering applications. Besides, the J-integral values of L-T direction specimens are much higher than those of L-S ones. The J-integral values of rolled ring are:JC-R>JC-L>JL-R.
文摘A recent joint paper with Doina Cioranescu and Julia Orlik was concerned with the homogenization of a linearized elasticity problem with inclusions and cracks(see[Cioranescu, D., Damlamian, A. and Orlik, J., Homogenization via unfolding in periodic elasticity with contact on closed and open cracks, Asymptotic Analysis, 82, 2013, 201–232]). It required uniform estimates with respect to the homogenization parameter. A Korn inequality was used which involves unilateral terms on the boundaries where a nopenetration condition is imposed. In this paper, the author presents a general method to obtain many diverse Korn inequalities including the unilateral inequalities used in [Cioranescu, D., Damlamian, A. and Orlik, J., Homogenization via unfolding in periodic elasticity with contact on closed and open cracks, Asymptotic Analysis, 82, 2013, 201–232]. A preliminary version was presented in [Damlamian, A., Some unilateral Korn inequalities with application to a contact problem with inclusions, C. R. Acad. Sci. Paris, Ser. I,350, 2012, 861–865].