Shear deformability characteristics of a rapid-cure woven prepreg fabric

Abstract

Formability of a continuous fiber-reinforced material is known to be influenced by its intraply shear behavior. This study investigates a 2 × 2 twill weave carbon fabric and the corresponding vinyl-based thermoset prepreg developed for press-cured structural parts. Intraply shear tests of bias-extension and picture-frame were conducted for a range of industrial-relevant processing conditions of temperature and shear rate. The dry fabric was characterized similar to the prepreg to isolate the influence of semi-cured resin on the woven prepreg fabric formability in shear. The shear deformation behavior of the prepreg, usually dependent on the fabric architecture, is found to be controlled by the state of the resin. The results clearly show the significance of the choice of process parameters on the prepreg shear behavior. It is demonstrated that preheating the prepreg to temperatures considerably lower than required to initiate cure can make the shear formability of the woven prepreg equivalent to the constituent (dry) reinforcement fabric. The actual shear angle measurement during the bias-extension tests demonstrates the level of inter-tow slippage for the prepreg fabric at relatively elevated temperatures. The comparison of normalized shear data from the two test methods helps to determine the improved procedure for prepreg fabric testing.

Real-Time Image Defect Detection System of Cloth Digital Printing Machine

“…Through multichannel differential operation on the image, the defect information is extracted. This method can continuously update and correct the reference image with the industrial production process, but this method is greatly affected by light and noise in the defect detection of printed fabric [ 10 ]. Steel and Hartinger proposed a fabric printing color displacement detection method based on normalized cross-correlation.…”

Shear performance assessment of repaired honeycomb sandwich composite panels: An experimental and numerical study

“…Picture frame test is a kind of experimental tests for characterizing the material behavior of textile composites. In recent years, the frame test has been widely used to measure the shear properties of carbon/glass fiber composite laminates and plain weave fabrics 27–32 . DIC system is a good choice for measuring the strain of sandwich panels.…”

“…In recent years, the frame test has been widely used to measure the shear properties of carbon/glass fiber composite laminates and plain weave fabrics. [27][28][29][30][31][32] DIC system is a good choice for measuring the strain of sandwich panels. Macro-scale DIC is used in the picture frame test and employed to study the distinct shear failure patterns of sandwich core materials.…”