Leon Stenholt Johansen

Optimization of Laminated Composite Structures Using Delamination Criteria and Adaptive Models

Laminated composite shell structures are becoming increasingly popular because of good stiffness/ strength to weight properties. The matrix material bonding the fibres together is weak compared to the reinforcing fibres, and laminated composite structures thus can fail because of delamination due to high transverse stress levels. In this work the objective is to optimize laminated composite structures against delamination failure. Due to many material layers in laminates, it is necessary to reduce the number of degrees of freedom in finite element models by use of Equivalent Single Layer (ESL) elements, to be able to describe the global response of laminated shell structures. When doing so information about the detailed response of the laminate is lost and it is not possible to predict delamination failure accurately. Adaptively refined analysis models are introduced to overcome this issue.

Multi-Criteria Multi-Material Topology Optimization of Laminated Composite Structures

The design of laminated composite shell structures is a challenging problem, and in order to obtain a cost effective design, it is desirable to have a general computer aided tool that can generate a high performance topology in the initial design phase. In this work the potential of using the so-called Discrete Material Optimization (DMO) approach for multi-material topology optimization is studied for multi-criteria design where conflicting design criteria such as mass, compliance, buckling load factors and local failure criteria are taken into account. Examples are given for a generic main spar from a wind turbine blade.