116 - TECHNICAL STRENGTH THEORY OF ELASTIC COMPOSITE LAMINATES (CompTest 2025)
T The simple strength theory of CFRP type laminates is proposed, which make possibly can be found the strain-strength properties of lamina in situ and assessment the laminates strength using end formulas without lamina-by-lamina analysis. The simplified failure criterion of a lamina according to the condition of matrix fracture is given. This fracture occurs when the criterion function reaches its greatest value on a certain plane. On this critical plane stress vector has the smallest value and according to the point of parametric conical limiting surface [1, 2]. The parameter is inclination angle of critical plane to fibres plane. The relations for determining the material constants of this criterion from standardized tests or also determining they’re in situ from the tests of check piece laminates or the witness samples are found. The equation for finding the orientation of the critical plane in case 3D stress is obtained. For cases where there are no tangential stresses across or along the fibres, the fracture criterion is given in final form, only through the components of the stress tensor. Also, explicit the criterion is given for a plane stress state. The stress ranges corresponding to the critical plane orthogonal or inclined to the plane of the fibres are determined. It is shown that for the orthogonal orientation of the critical plane, the obtained fracture criterion is linear, for inclined it is quadratic. An experimental verification of this criterion and its comparison with known fracture criteria for volumetric, plane and one-dimensional loads has been carried out. Its best correspondence to experimental data is shown that for many more complex criteria.
Date
21.05.2025.
Keywords
Laminated composites, Fracture criteria for matrix and fiber, Lamina properties, Strength
