Optimal design of sandwich panels with hybrid core

The main aim of the paper is to find optimal solutions of sandwich panels with flat steel facings and a hybrid core made of aerogel and polyisocyanurate (PIR) foam. The optimal solutions have to satisfy conflicting criteria, i.e. a maximum range of applications and minimum weight, while at the same time respecting both the principles of sustainable development in the construction industry and the limit states (ultimate and serviceability) conditions. The design vector consists of the geometrical parameters of the sandwich panel including its span length and the parameter which describes the proportion of aerogel thickness to the total thickness of the core. The mechanical properties of the hybrid core are described by mathematical functions which were obtained in laboratory tests. In optimization, an evolutionary algorithm was used. The Pareto results were obtained while respecting the inequality constraints introduced in the optimization procedure directly (box conditions) and by means of the external penalty function. The presented optimization of a sandwich panel extends the class of problems discussed in the literature by considering both the hybrid core and the thermal conductivity aspect.