|Alternative Title||Thermal-mechanical damage behavior of carbon fiber reinforced epoxy composite laminate by laser irradiation|
|Thesis Advisor||魏炳忱 ; 吴臣武|
|Place of Conferral||北京|
Carbon fiber reinforced plastic has been widely used in aerospace and other fields due to their excellent mechanical properties and design adaptability to the service environment. Because of the performance evaluation of the thermal irradiation zone in the laser processing of this composite laminate and the laser thermal damage design of the unmanned aerial vehicle with the composite laminate as its main structure, it is necessary to accurately understand the laser irradiation temperature field, thermal stress and damage mechanism of the composite laminate in the relatively low energy density.
The thermal damage pattern of composite laminate may be very complicated due to the anisotropy of composite laminate, the diversity of laminates and the time-domain instability and spatial heterogeneity of laser irradiation thermal load. However, since the interlaminar region of composite laminate only contains the resin substrate and constitutes a relatively weak region, the thermal damage under the action of laser irradiation is likely to be concentrated in these local regions, forming a failure mode dominated by interlaminar cracking.
In order to reveal the composite laminate under the irradiation of laser thermal damage behavior, especially the interlaminar fracture mechanism, this paper will study the temperature field, thermal stress field and damage failure behavior of composite laminates under laser irradiation step by step, using the method of theoretical analysis, numerical simulation and experimental observation, focusing on revealing the interlayer cracking behavior of composite laminates under laser irradiation and the law of parameter dependence. The research work is mainly elaborated from the following three parts:
Part I: in order to study the thermal response of composite laminate irradiated by continuous laser, the transient temperature field and its evolution process of composite laminate irradiated by laser are studied. Using Laplace transform and Fourier cosine transform, the analytic solution of the transient heat conduction problem of composite laminate under continuous laser irradiation is derived. In addition, the 3-d transient heat conduction finite element analysis of laser irradiated composite laminate under the same conditions was carried out. At the same time, the dependence of the temperature on the typical parameters of the composite laminates irradiated by laser is studied by using analytical and numerical solutions.
Part ii: in order to study the thermal stress field of composite laminate subjected to continuous laser irradiation, the analytical solution of stress and strain field of composite laminate subjected to continuous laser irradiation was derived based on the shear deformation theory and variational principle. Taking the analytical solution of the temperature field of laser irradiated composite laminate as the input thermal load, the thermal stress decomposition of composite laminate under a given temperature field is solved. Then a three-dimensional thermoelastic finite element model including material cracking was established for the thermoelastic response and interlaminar cracking behavior of composite laminate under continuous laser irradiation. The interlayer cracking process of composite laminate under continuous laser irradiation is preliminarily simulated by coupling/decoupling method of interlayer interface nodes.
Part iii: in order to reveal the thermal damage mechanism of composite laminate by laser irradiation, the experimental study on laser irradiation of carbon fiber reinforced resin matrix composite laminate was carried out. The characteristics of interlaminar cracking were observed by means of optical microscope and scanning electron microscope, and then the pulsed laser ablation behavior and the law of laser parameter dependence of carbon fiber reinforced resin matrix composite laminate were studied experimentally.
|刘彦池. 激光辐照碳纤维增强环氧树脂基复合材料层合板热力破坏行为[D]. 北京. 中国科学院大学,2019.|
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