Residual Stressesin intrinsic hybrid laminates, detection, modification and consideration in manufacturing and the numeric damage modeling

由于各构件的热性能不同以及混杂CFRP-金属-复合材料的各向异性，导致混杂复合材料在生产过程中存在较高的残余应力，从而降低了混杂复合材料的强度。该项目旨在研究减少层间应力的措施。因此，对现有的或新生的残余应力的测量技术进行了研究。重点在于将光纤传感器直接集成到未固化的纤维增强聚合物中的应用。随后研究了修正残余应力水平的措施。参数质量筛选揭示了材料参数和工艺参数之间的因果关系，以及层间残余应力。此外，内部应力的不对称叠加导致了工艺引起的曲率或挠度等变形。曲面结构表现出显著的复杂应力状态。开发的测量原理将被采用，以便除了确定残余应力之外，还可以作出关于工艺引起变形的来源的陈述。利用第一个注资期对残余应力的来源、不同内在和外在因素的影响的认识，发现了由结构曲率、不对称性和嵌入残余应力引起的过程引起的变形之间的因果关系。除了减小这些应力的措施外，还研究了用于制造混合结构尺寸精确的结构的补偿方法。利用所开发的补偿方法制作了用于计算机辅助教学研究的精密平板不对称试片。对损伤行为的影响将通过实验进行研究。

The different thermal properties of the components as well as the anisotropy of hybrid CFRP-metal-composites lead to intrinsic high residual stresses during the production processes reducing in turn the strength of the hybrid composite. The project aims to investigate measures to reduce the interlaminar stresses. Therefore, measurement technologies are investigated for measuring the existing or nascent residual stresses. The focus lies on the application of fiber optical sensors being directly integrated into the uncured fibre reinforced polymer. Measures for modifying the level of residual stresses are investigated subsequently. Parametric mass screenings reveal the cause-effect relationships between the material parameters and the process parameters as well as the interlaminar residual stresses.Beside the intrinsic stresses asymmetric layups lead to process-induced deformations like curvatures or deflections. Curved structures exhibit significant complex stress states.The developed measurement principle will be adapted such that beside the determination of the residual stresses statements about the sources of process-induced deformation can be made. The achieved perceptions from the first funding period about the origin of residual stresses, the influence of different intrinsic and extrinsic factors are used to discover the cause-effect relationships between the process-induced deformation evoked by the structural curvature, the asymmetry, and the embedded residual stresses. Beside measures for reducing these stresses compensating methods for producing dimensionally accurate structures are investigated for hybrid structures. The developed compensating methods are used to manufacture accurate flat asymmetric coupons for CAI investigations. The effect on the damage behavior will be investigated experimentally.