The interfacial adhesive properties ofpolypropylene/stainless steel were studied by the blister test. The polypropylene film with a squared free-standing window was pressured by oil from one side of film. The corresponding deformation field was observed by a digital speckle correlation method. The experimental results show that the squared film deforms and debonds from stainless steel with the increase of pressure. The debonding of the squared film in initiates from the center of edge and extends to the comer, and then the deformation of film evolves from square to circle shape. The interfacial adhesive energy of polypropylene/stainless steel is （22.60±1.55） J/m2, which is in agreement with that measured by film with a circular window.
The effect of a variety of geometrics, initial conditions and material properties on the deformation behavior of thin films in the plane-strain bulge test was systematically scrutinized by performing the finite element analysis, and then the accuracy of the plane-strain bulge test in determining the mechanical properties of thin films in terms of our finite element results was analyzed. The results indicate that although the determination of the plane-strain modulus in the light of the plane-strain bulge equation is fairly accurate, the calculation of the residual stress is not satisfied as expected, especially for low residual stress. Finally, an approach is proposed for analyzing bulge test data, which will improve the accuracy and reliability of this bulge test technique.
采用数值模拟方法研究了激发频率对声波层析成像技术检测钢筋混凝土构件内缺陷反演精度的影响。利用有限元分析软件建立不同配筋率的钢筋混凝土模型,对弹性波在钢筋混凝土构件中的传播进行模拟和计算,在此基础上应用声波层析成像分析软件对其剖面成像,对比激发频率分别为100 k Hz和200 k Hz的声波层析成像反演结果。研究表明不同激发频率对声波层析成像技术检测不同配筋率混凝土缺陷具有一定影响,当激发频率为200 k Hz,且配筋率比较小时,声波层析成像技术对混凝土构件中孔洞缺陷与钢筋的检测比较敏感;而当激发频率为100 k Hz,且配筋率比较大时,声波层析成像技术能够定位混凝土构件内缺陷位置,伪像干扰小。
Based on load-displacement curves,indentation is widely used to extract the elastoplastic properties of materials.It is generally believed that such a measure is non-unique and a full stress-strain curve cannot be obtained using plural sharp and deep spherical indenters.In this paper we show that by introducing an additional dimensionless function of A/A (the ratio of residual area to the area of an indenter profile) in the reverse analysis,the elastoplastic properties of several unknown materials that exhibit visually indistinguishable load-displacement curves can be uniquely determined with a sharp indentation.
