Investigation of bolt torque and environmental conditioning on the mechanical performance of bolted composite laminates
Year: 2026
Type: article
Abstract: • Effect of torque level and environmental conditioning in filled hole tensile test. • Humidity did not affect the filled hole strength at room temperature. • Torque level and testing temperature strongly impact filled hole tensile strength. • Low torque resulted in higher filled hole strength in all testing condition. • Hot and wet conditions are the most critical case for high torqued specimen. • The most critical case for low torqued specimens is testing at room temperature. One of the most widespread methods of joining composite structures in the aerospace industry is using mechanically bolted joints. In this paper, the combined effect of fastener torque, temperature, and humidity on the mechanical performance of aerospace grade bolted composite laminates is investigated experimentally and numerically. Unconditioned and conditioned (85°C and 85% relative humidity) quasi-isotropic filled-hole and open-hole carbon fibre reinforced polymer composite laminates are subjected to quasi-static tensile loading at ambient/room (25°C) and elevated (120°C) temperatures. Three fastener torque levels are considered for the filled-hole specimens: 1 Nm (hand-tightened), 7.7 Nm, and 15.4 Nm. High-fidelity linear/elastic finite element (FE) models are constructed, utilising the LaRC05 damage initiation criterion, to further investigate the underlying failure mechanisms. It is shown that the applied clamping force and testing temperature have a considerable influence on the filled-hole tension strength (up to 10%) and failure modes, while the moisture content has negligible effect. Furthermore, low fastener tightening torques resulted in higher filled-hole strengths, regardless of environmental conditioning and testing conditions
Source: Composite Structures
Institutions: University of Bristol, BAE Systems (United Kingdom)
Language: English
Subfield: Mechanics of Materials
Field: Engineering
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $4,660
OpenAlex ID: W7125599656