Experimental Study on Hoop Stress Affecting Braided Carbon Fiber Reinforced Plastics Subjected to Internal Pressure

Braided carbon fiber reinforced plastics (CFRPs) can be employed in the construction of pressurized vessels to increase performance and reduce overall weight. However, owing to the complex braiding structures resulting from the braiding process, an analysis of the elastic modulus is important as it affects the hoop stress on the pressure vessel. In this study, braided preformed CFRP constructed on a steel cylinder subjected to internal pressure was experimentally investigated using a simple approach that involved estimating the elastic modulus and hoop stress. Five types of braided preformed CFRP with different braiding angles and number of applied layers were analyzed. The elastic modulus and hoop stress can be estimated from these measurements of the internal pressure. The differences in the braided structures result in different strain values and affect the elastic modulus. High braiding angles tend to be more stable against high internal pressure, and exhibit small strain differences and high elastic modulus in the hoop direction. Similar results were observed when additional layers were applied. Increasing the braiding angle and the number of layers can increase the average elastic modulus.