Different Bending Stress Analysis Of Double Material Interface Cracks

"Composite" is the mystery of the composite material, Through thecompound, new performance can created, which is the original material. Atthe same time, the composite materials tend to damage near the junction, orinterface. So, this needs us to analysis of interface crack fracture in-depth, sothat the strength and reliability of the composite material reaches a certaindegree. The bending problem’s analysis of the composite material, is particularlyimportant, because of the bending problem’s use widely in life, especially thebending problem of interface crackIn this paper, the bending fracture problems of the isotropic and orthotropicmaterials are studied. According to the plate bending theory，the basic equationof bending problem under isotropic and orthotropic material interface crack isestablished. Through the complex function theory, introducing the deflectionfunction of contain of undetermined coefficients and the eigenvalue analysismethod, the solution is to a class of boundary value problems of partialdifferential equations, and a theoretical formula of bending moment, torque andstress is obtained of central penetrated interface crack tip in the loading of purebending, pure twisting or bending and twisting under isotropic and orthotropicmaterials. When the up-down material is same, the calculation formula ofbending moment, torque of isotropic material can be obtained and the results canbe verified in accordance with the existing results. The main results are asfollows:1. The characteristic equationΔ₂＞0and Δ₂＜0under loads of pure bending, puretwisting or bending and twisting under isotropic and orthotropic materialcentral penetrated interface crack tip,the calculating formula of bendingmoment, torque, stress and strain is established2. The stress value of drawing is established of the isotropic and orthotropicdouble materials curved interface crack tip, along a certain direction, differentdiameter distribution regularity. Results show that when placed in thedirection of elastic modulus increasing, isotropic material of the upper plate, （σ_x）₁and（σ_y）₁increasing, the absolute value of（τ_xy）₁decreases; ForOrthotropic material plate，（σ_x）₂and（σ_y）₂decrease，（τ_xy）₂appear staggeredup and down phenomenon, overall look at absolute value smaller. Thesestudies provides theory basis for the structure design of bending interface ofisotropic and orthotropic materials.