چكيده به لاتين
According to the growing demand of global markets to increase the safety of cars on the one hand and also the need for high-quality but light structures, especially with the development of the growing trend of electric car production and, on the other hand, the use and application of new simulation methods and optimization will be inevitable. A major reason for this issue is the highly non-linear nature of problems related to the analysis of the vehicle body structure during an accident. In this way, the loading on the structure, the boundary conditions and also the mechanical properties of the components of the car structure will be changing at a very high rate during the accident. On the other hand, the restrictions imposed on the design and optimization of the vehicle structure, which are mainly focused on reducing weight with the aim of reducing fuel consumption and improving efficiency, require the use of advanced optimization algorithms. This issue adds to the complexity of the issue in the analysis of composite structures, which have a much more complicated mechanism than metal structures in absorbing energy. Energy absorption in a structure is the ability to convert all or part of the kinetic energy of collision into other forms of energy, which in metal structures is mainly based on the folding of components, but in composite structures, it is a combination of delamination, fiber breakage Fiber breakage, matrix cracking, separation of fibers from the matrix, debonding, etc. By reviewing the related research in the field of simulation of composite energy absorbers, the lack of a principled and reliable method in numerical simulation is quite evident and is emphasized. On the other hand, the effect of fiber angles on energy absorption capability has not been investigated in the researches so far, taking into account the possible uncertainties of fiber angles (which are unavoidable in the production and manufacturing process of composites). In this research thesis, an attempt has been made to simulate the energy absorption of a composite structure under axial loading with reliability and reproducibility in mind for the first time. Also, the effect of fiber angles on two main characteristics of energy absorption, specific energy absorption (SEA) and impact force effectiveness (CFE) will be investigated. In this direction and in the first step, all the mechanical properties of the composite were calculated and extracted based on ASTM standard tests. Then, the non-physical parameters of composite simulation, taken from the theories of damage and destruction of composite, were systematically checked and optimized in a way to achieve the best match between experimental test and numerical simulation. In the final step, using an optimization method based on probabilistic uncertainty, the effect of fiber angles on the energy absorption efficiency of the composite cylindrical cylinder is evaluated based on SEA and CFE parameters, and the optimal response is extracted and compared based on precise and probabilistic optimization. The extraction and reporting of the effectiveness of non-physical coefficients of numerical simulation as well as the investigation of fiber angles based on probabilistic uncertainties were among the innovations of this treatise. Also, all the physical and experimental parameters of the numerical simulation of this research have been carried out from standard experimental tests on completely similar samples (in terms of the composition of ingredients and manufacturing method), which are unique features of this research.
