Effects of Surface Damage Layer on Structural Global Deformation and Stiffness
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摘要: 基于等效介质概念,对含表面微裂纹构件的力学特性进行了分析,给出了损伤层的定义,建立了含表面微裂纹的梁结构的等效双材料组合梁模型,推导了含损伤层梁的挠曲线微分方程,研究了损伤层对梁的弯曲变形的影响,给出了梁的挠度变化与损伤层厚度及等效弹性模量的关系,同时,分析了损伤层厚度及模量对梁的刚度的影响。分析计算结果表明:随损伤层厚度的增加,梁的挠度增大,刚度减小;随损伤层弹性模量的减小,梁的挠度增大,刚度减小;当损伤层厚度达到梁高的1/30以上时,损伤层对梁的弯曲变形和刚度影响较大,对机械加工的精度有较大影响。Abstract: In this paper the mechanical properties of the cracked structures are investigated using the equivalent medium theory. Based on the definition of the surface damaged layer,the two-material composite beam is used to model the cracked beam. The differential equation of the deflection curve of the cracked beam is deduced. The effects of the damaged layer on the bending deformation are studied. The relation among the beam deflection,the thickness of the damaged layer and the equivalent elastic modulus of the damaged part is obtained. In addition,the influence of the damaged layer thickness modulus on the beam stiffness is also evaluated. The numerical results reveal that the deflection of the beam will increase and the stiffness of the beam will decrease as the thickness of the damaged layer increases or the elastic modulus of the damaged layer decreases. When the thickness of the damaged layer is larger than 3% of the thickness of the beam,the influence of the damaged layer on the deflection and stiffness of the beam are so obviously that will affect the accuracy during the manufacturing process significantly.
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Key words:
- deflection ( structures) /
- microcrack /
- calculations /
- differential equations /
- mechanical properties
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