Process-induced residual stresses in 3D woven carbon-epoxy composites are studied by blind hole drilling experiments interpreted with finite element (FE) modeling. It is assumed that residual stresses are primarily caused by the difference in thermal expansion coefficients of the constituents which are modelled as temperature-dependent linear elastic solids. The impact of residual stresses is quantified by drilling blind holes in the composite panels and mapping the resulting in-plane surface displacements by electronic speckle pattern interferometry. Mesoscale finite element models are used to correlate these surface displacements with the volumetric distribution of the residual stresses in the composite. This is done by determining the effective temperature drop ΔT^eff that results in the same predictions for the surface displacements as experimentally measured. The effective temperature drop approach allows to use linear elastic models while approximately accounting for various nonlinear effects occurring in the material during processing. The models are also used to establish the sensitivity of the predicted results to the exact location of a hole and its depth.

通过用有限元（FE）建模解释的盲孔钻探实验研究了3D编织碳-环氧复合材料中过程引起的残余应力。假定残余应力主要是由建模为温度相关的线性弹性固体的成分的热膨胀系数差异引起的。残余应力的影响可通过在复合面板上钻出盲孔并通过电子散斑图干涉法绘制所产生的平面内表面位移来量化。中尺度有限元模型用于将这些表面位移与复合材料中残余应力的体积分布相关联。这是通过确定有效温度下降量^{ΔTeff来完成的}对表面位移的预测与实验测得的结果相同。有效的温度下降方法允许使用线性弹性模型，同时大致考虑了加工过程中材料中发生的各种非线性效应。该模型还用于建立预测结果对孔的精确位置及其深度的敏感性。