Investigation of mechanical behavior of weld seams of composite envelopes in airship structures

With the favorable space retaining advantage, airship structures provide a cost-effective approach for the high altitude payload platform. While composite envelopes, the key material for an airship capsule, were extensively studied, the mechanical behavior of weld seams remained unclear. As weld seams may be the authentic controlling factor for the mechanical performance of airship structures, a comprehensive study on its mechanical behavior is necessary. An in-depth investigation revealing the tensile properties of weld seam was carried out in this study. Three types of weld seam specimens were designed and manufactured. To illustrate the microstructure of the weld seams, an electron scanning microscope apparatus was employed conducting observation. Systematic tensile tests were performed on envelopes, weld tapes and weld seams. It was found that the failure occurred at the heated zone rim. Furthermore, noncontact measurement was utilized obtaining the global strain field, based on which elastic constants were calculated. Eventually, a numerical model was proposed to simulate the tensile behavior of the weld seam.