Effectiveness of epoxy staking of fasteners in aerospace applications

Abstract

PurposeThe purpose of this paper is to investigate the effectiveness of locking or staking of fasteners with epoxy material systems to prevent loss of preload in aerospace environments.Design/methodology/approachA quantitative experimental method is adopted to evaluate epoxy material systems for staking of fastener assemblies subjected to varying dynamic and thermal loads. A statistical design of experiments is employed to probe specific design parameters.FindingsResults show that epoxy application can provide satisfactory fastener locking under a variety of service conditions. It is found that: Epon 828 epoxy provides superior fastener locking compared to 3M Scotch‐Weld Epoxy 2216; epoxy application around screw threads is more effective than application around screw head; and abrading the plate surfaces with 180 grit SiC paper is not an effective or useful surface preparation technique.Research limitations/implicationsThe paper is limited to two commercial epoxy material systems and does not consider important qualitative considerations for industrial use such as cure time and viscosity.Practical implicationsThis and future paper may form the basis of new standards for epoxy staking in the global aerospace industry.Originality/valueThis paper is believed to be one of the very few original experimental studies of fastener staking available in the open literature.

Process-Related Changes in Polyetherimide Joined by Friction-Based Injection Clinching Joining (F-ICJ)

“…The stake head is not damaged in such a failure mode. Differently from fastener staking [46], THFSW [1], and FFSJ [2] joints, the joining mechanism of F-ICJ does not depend on polymer-metal adhesion, as it relies mostly on the mechanical interlocking of the components. Typically, the lower strength and degradation of the PTMAZ will not influence the reliability of assemblies suffering loads as from cross tensile test.…”