Calculation of Principal Directional Strains of Layers Inside Carbon Fiber Laminates Based on Sequential Strain Measurements

The article proposes a method to calculate the main direction strain inside the carbon fiber laminate based on the measured strain on the surface. The method is to paste strain gauges on the surface of the laminate, and the main direction strain inside the laminate is deduced through the selection of strain gauges, the determination of the paste method, the acquisition and processing of data, and the combination of the relevant theories of mechanics of materials and mechanics of composite materials. This method effectively solves the difficult problem of strain measurement inside carbon fiber laminates. The article validates the method with different layers of the laminate as test objects. The accuracy of the strain measurement of the surface layer and the validity of the calculation of the main directional strain of the internal layers based on the measured strain are verified by means of tests and finite element software calculations.