Hoernig, T., "Increased thread load capability of bolted joints in light weight design," SAE Technical Paper 2017-01-9453, 2017.
Within the scope of today’s product development in automotive engineering the aim is to produce more light and solid parts with higher capabilities. On the one hand lightweight materials such as aluminum or magnesium are used, but on the other hand, increased stresses on these components cause higher bolt forces in joining technology. Therefore screws with very high strength rise in importance. At the same time, users need reliable and effective design methods to develop new products at reasonable cost in short time. The bolted joints require a special structural design of the thread engagement in low-strength components. Hence an extension of existing dimensioning of the thread engagement for modern requirements is necessary. In the context of this contribution, this will be addressed in two dimensions: on one hand extreme situations (low strength nut components and high-strength fasteners) are considered. On the other hand the thread reinforcement by use of wired thread inserts is investigated which can improve the pull-out-force of the thread. In this paper a verified and manageable dimensioning method for thread engagement in light-weight design with extreme situations and in combination with wired thread inserts is presented. The quantitative proof of a performance increase by screw connections with threaded inserts is shown. The analytical dimensioning method is ensured by experimental investigations on the one hand and on the other hand by numerical calculations. As a message of this paper a design engineer can develop thread engagements with enhanced loading capacity – customized for his light weight design application.