Reliability analysis of seam joints in square plain parachute canopy fabric

摘要

Performance of parachute continuously degrades due to opening shock and dynamic pressure acting on its various components after opening. During repeated use of parachute, degradation in tensile strength of canopy fabric plays an important role. Measurement of probability of successful operation of parachute in repeated use and under impact loading is possible through reliability analysis of its seam joints. Present study mainly concerned with the reliability analysis of the performance of square plain parachute canopy joined in parallel at different bias angle. The impact loading of the specimen degrades its tensile property and the extent of loss depends on its bias angle of stitching. However, the deterioration of performance in terms of tensile strength is more as compared to breaking elongation. Without subjecting any impact, specimen stitched at 0 degrees and 45 degrees have almost same breaking strength. However, impact loading degrades the tensile property of specimen with 45 degrees bias angle to a greater extent as compare to specimen with 0 degrees bias angle. As regards breaking elongation of specimen, the specimen stitched at 45 degrees bias angles always exhibits highest value (even after impact loading) than the specimen stitched at other bias angles. The reliability analysis of seam joints shows that the specimen stitched at 0 degrees bias angle is most reliable among other angles of stitching in terms of maintaining tensile strength for longer impact cycle.