Combined Moisture Diffusion and Mechanical Computational Analysis of Composite Bondlines,
Abstract
A combined moisture diffusion and mechanical computational analysis methodology was developed as part of an Independent Research program at Lockheed to enhance our understanding of nonlinear and coupled physical processes in materials. The physical behavior of interest is the mechanical response of composite material systems to environmental conditions which can change the materials' moisture content. In particular, it is desirable to know what set of environmental conditions will affect the integrity of a partial adhesive bondline when a bondline gap (no adhesive) is present. The Lockheed proprietary finite element code (DIAL) was modified to analyze this phenomena in two stages: (1) the temporal moisture partial pressures in the materials are calculated from initial and environmental boundary conditions and (2) these partial pressures are then passed to a quasi-static mechanical analysis where the moisture data at each time step is treated as a dilatation (swelling) load. The resultant stress and strain state is then calculated, as well as gap closure, if any. Demonstration of this methodology was on a relatively simple 2-dimensional axisymmetric example problem. The results show primarily compressive stresses caused by the positive dilatation (swelling) induced by moisture intrusion into the structure. The stresses concentrate at adhesive bondlines, and bondline gap behavior (i.e., the absence of a contiguous adhesive bond at material interfaces) is correctly simulated. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Nov 01, 1984
- Accession Number
- ADP005004
Entities
People
- D. Wadiak
- S. Mchugh
Organizations
- Lockheed Martin Missiles and Space