封闭加固型计算机板卡锁紧结构接触热阻分析

针对封闭加固型计算机芯片冷板和机箱导轨间的界面传热问题，利用有限元软件对两种常用的导轨锁紧结构(3J和5J结构)进行了建模与分析，通过比较接触压力和接触热阻分布特点，发现在相同条件下5J结构具有更低的接触热阻.随后，以5J结构为研究对象，详细分析了螺栓扭矩和表面粗糙度对其接触热阻的影响，发现增加螺栓扭矩或减小表面粗糙度虽然都可以减小接触热阻，但增加螺栓扭矩引起的热阻降幅较小，且还会产生较高的接触压力，不利于长期使用.原因分析表明:机箱导轨刚度不足是导致界面接触不均、热阻分布不均和平均热阻偏大的主要原因，因此对机箱导轨的结构与尺寸进行了优化.计算表明，优化后的结构不仅显著降低了接触热阻，而且大幅减小了界面接触压力，减小效果在螺栓扭矩较大、表面粗糙度较小时更为明显.

Analysis on Thermal Contact Resistance of the Connecting Structure in Enclosed Rugged Computer

The present work focuses on the thermal contact resistance (TCR) at the interface between the cooling board and the chassis rail in the enclosed rugged computer (ERC). Two types of connecting structures (3J and 5J structures) used in the ERC are studied using the finite element method (FEM) analysis software. Firstly， the contact pressure distribution and TCR distribution at the interface between the cooling board and the chassis rail are both studied. It is found that the TCR in 5J structure is much smaller than that in 3J structure. Secondly， the influences of bolt torque and surface roughness on the TCR of 5J structure are studied. The results show that TCR decreases with increasing bolt torque or decreasing surface roughness. However， a high bolt torque would result in a high contact pressure what may lower the service life of electronic devices. Further analysis shows that low stiffness of the chassis rail results in an inhomogeneous contact that leads to an inhomogeneous TCR distribution and high average TCR. Based on these findings， an optimization on the chassis rail is carried out to reduce both the average TCR and the contact pressure successfully. Moreover， the results show that the decrease in average TCR induced by the above optimization can be enhanced by increasing bolt torque or decreasing surface roughness.