This research work summarizes the study of the structural analysis of shear webs (present in wind turbine blades, sometimes also called as spars) with holes. The webs are sandwich composite structures which are supposed to carry the shear loads coming from the wind pressure and the holes are necessary for non-structural requirements of the wind turbine.
The shear webs are strong structures and it is tough to test them to failure in the lab. Hence a structural representative component with lesser dimensions has been tested in the lab to accommodate the capability of the test machines.
However, this component test results cannot be directly used in the wind turbine blade structural verification as the web size is much larger in real life.
A finite element model is developed to simulate the test specimen and its failure behavior. The concept in this modelling approach is to prepare a digital copy of the actual specimen which will follow the same load-displacement behavior and can predict the same failure as seen in the test coupon.
The finite element model is verified for failure using known failure criteria for composite sandwich structures as well as with analytical calculations. This makes sure that the finite element model is a good ‘digital twin’ and simulates the test component behavior one to one. Later, this finite element model is extended to the size of the actual web structure (a family of FE models with different dimensions) to scale up the failure prediction to actual stiffness level.