Research And Application Of Structural Dynamics Topology Optimization Design Method For Additive Manufacturin

Structural dynamic performance design is a key issue that must be solved in the lightweight design process of complex structural products such as aviation,aerospace,and weapons.Restricted by traditional design concepts and manufacturing processes,the discontinuous design mode is very easy to interfere and damage the optimality of the structure,which limits the optimization design space of the structure and makes the improvement of product performance limited.Additive manufacturing technology greatly expands the design freedom of products with complex structures and provides new opportunities for structural lightweight design.The optimization design method of structural dynamics topology for additive manufacturing has become the most potential way to improve the payload,flight range,and maneuverability of aircraft and land warfare equipment.This dissertation aims at the topology optimization design of structural dynamics driven by additive manufacturing,and carries out the research of structural dynamics topology optimization design methods from the two dynamic dimensions of time domain and frequency domain,and constrains structural dynamics functions and additive manufacturing processes Constraint synchronization is introduced into the topology optimization design process,which realizes the collaborative optimization of structural design and functional design.The main research results include:(1)Aiming at the goal of structural dynamics topology optimization design,a topology optimization method based on linear interpolation material model is proposed.By constructing mathematical models of stiffness sensitivity and natural frequency sensitivity,and considering additive manufacturing process constraints,a voxel addition and deletion strategy oriented to additive constraints is established.The location mapping of voxel units and the performance mapping of linear interpolation materials avoid local modal problems,and a bidirectional progressive(BESO)linear interpolation material model is established.(2)Aiming at the topology optimization problem of time domain dynamics,a twolayer optimization strategy based on equivalent static loads is proposed.For the multiobjective time-domain topology optimization model obtained by static equivalent,the optimization of the outer weighting factors and the optimization of the inner design variables are carried out simultaneously to obtain a feasible solution that meets the timedomain performance requirements.Take the time-domain dynamics design of a mortar seat model as an example,based on the use of internal and external division of the design domain and two-layer optimization strategies to obtain a three-layer bearing structure that satisfies the full-time domain conditions.Considering additive manufacturing process constraints,combined with the BCC truss lattice structure,realized the integrated topological lattice design of the seat plate,reducing the weight by 54.5%.(3)Aiming at the problem of frequency domain dynamics topology optimization,a critical stiffness-driven frequency domain dynamic topology optimization design method is proposed.Using critical stiffness conditions and volume constraints,the original optimization model is relaxed into two continuous optimization models,combined with the progressive volume characteristics of the soft-kill BESO method to avoid repeated iterations of weighting factors,and volume-weighted coupling is realized.Taking the lightweight design of a satellite bracket as an example,the optimization results under the compiled dynamics optimization program are 40%lighter than the original design,and the natural frequency is increased by more than 30%.(4)In order to verify the validity of the numerical results of the dynamic optimization,a soil coupling simulation analysis was carried out for the new seat plate to verify the performance and stability of the new design;a sweep frequency vibration test and a compression test were designed for the bracket.Compared with the pure stiffness design,the dynamic design sacrifices 6%static stiffness,and the first and second natural frequencies are increased by 62%and 15.4%,respectively,which verifies the effectiveness of dynamic optimization.