关键词: 双搭接, 复合材料连接结构, 钉载均匀化, 钉孔间隙, 组合优化策略, 有限元, NLPQL算法

Abstract: This paper proposes a fast optimization method for nail load homogenization of double-lap composite joints by ad-justing the clearance of nail holes. Firstly, the optimal Latin hypercube algorithm is used to study the influence of several dimensional parameters on the nail load distribution of the composite joints. The key parameters to achieve nail load uniformity are determined to guide structural design, and are verified by the 3D finite element model. Sec-ondly, the combined optimization strategy of the optimal Latin hypercube algorithm and NLPQL algorithm is used to achieve uniform bolt load in the composite joints by optimizing the bolt–hole clearance, which is verified by the 3D finite element model. Further, the concept of optimal curve is proposed based on the distribution of the optimal bolt–hole clearance. Based on the optimal curve, a fast optimization search was conducted to achieve uniformity of the nail load in the double-lap composite joint structure. Then, various joint structures are designed to study the effects of fastening torque, number of bolts and structural parameters on the optimal curve, and the applicability of the opti-mal curve is verified by numerical simulation. The study shows that the optimal curve can be utilized to maximize the uniform distribution of bolt load in the composite joints. For the six-row bolt composite joints, the load-carrying ca-pacity can be increased by over 15%. The effect of the increase becomes more pronounced with an increase in the number of bolts.

Key words: double-lap, composite joints, Nail load homogenization, bolt–hole clearance, combined optimization strategies, FEM, NLPQL algorithm