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结构光三维重建技术已广泛应用于工业检测领域,随着工业检测需求的不断提高,工业检测
技术的需求也愈发向微小化和高精度化方向发展。其中,远心镜头具备透视误差小、镜头畸变小、成像失真少等优秀特性,获得越来越多的关注。该文投影仪采用传统镜头,将传统结构光系统中的相机镜头替换为远心镜头,通过对传统两步标定法的改进,对相机的仿射模型进行标定,随后用已标定的相机对投影仪进行参数标定。实验结果显示,所开发的远心结构光系统具备能够实现小视野范围的高精度、高分辨率三维重建,并具有加大的测量景深,可用于半导体器件及微型零部件等目标的高精度
三维检测。 相似文献
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Numerical simulation of plate rigid restraint cracking tests based on cohesive element model 下载免费PDF全文
Cohesive element is developed from the Dugdal-Barenblatt model in the field of fracture mechanics. The mechanical constitutive relation of cohesive element can be artificially assumed depending on the specific applications. It has been successfully applied in the study of crystal plasticity/ brittle fracture process and decohesion between delaminations. In this paper, tensile experiments of large steel plate with different length of pre-existing cracks are conducted. Based on commercial software ABAQUS, cohesive element is adopted to simulate the tensile tests, and appropriate parameter values are obtained by fitting displacement force curves. Using these parameters, a numerical method is presented by applying cohesive element to thermo-elastic-plastic finite element method ( TEP-FEM) to simulate plate rigid restraint cracking ( PRRC) tests. By changing constitutive relation of cohesive element, dimensions of the model and welding conditions, the influence of welding restraint intensity and welding conditions on the crack propagation are discussed, respectively. Three types of welding cold cracking are simulated. Significant influence of welding cold cracking on resistant stress in welding line is captured by this numerical method. 相似文献
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该文以发表的海冰蠕变实验为基础,建立考虑损伤失效的非线性Burgers’海冰模型。此模型在Jordaan模型基础上考虑韧脆转变应变率影响,使原有模型应用范围扩展至较高应变率。在模型中引入经验损伤失效准则,以准确反映不同应变率、围压等工况下海冰损伤失效过程。应用FORTRAN语言,通过隐式积分中心法对此模型进行数值求解,并将其嵌入到有限元软件LS-DYNA中。对实验室尺度的柱状冰蠕变实验、真实尺度冰块-刚性板碰撞场景进行数值模拟,分析蠕变实验的轴向应变-时间曲线,讨论冰块碰撞得到的压力-面积曲线及碰撞力时历曲线。这些数值模拟结果与实验及真实碰撞结果吻合较好,验证此模型的正确性及其对工程实际进行模拟的可行性。 相似文献
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