Catálogo de publicaciones - libros

The unique optimization potential of sandwich sheets with respect to a defined criterion, e.g. weight reduction, originates from the combination of different materials into one sheet. Due to this material combination, the sheet behaves differently from conventional sheet materials during forming and in addition unique failure modes like delamination might occur. Within the framework of two, separate research projects these unique features of sandwich sheets were analyzed through practical experiments and FEM-analyses.

This study describes the manufacturing method based on metal powder injection moulding for micro porous metal components with high functionally graded sandwich structure. The effectiveness of sandwich structure produced by co-sintering and co-injection moulding processes to compensate the deficiencies on the mechanical property of porous structures, was investigated.

This study describes the manufacturing method and physical properties of sandwich structure tubes using cup-stacked carbon nanotube/polypropylene and polypropylene. The effectiveness of sandwich structure produced by sequential injection moulding to enhance the axial and transverse compressive properties of thermoplastics was investigated. It was shown that compressive properties of the sandwich tubes effectively improved by proportionally positioning rich nanotube materials to the outer layer.

Two new types of ROHACELLê foam specially designed for resin infusion processes are now commercially available. In comparison to the heat resistant ROHACELLê type the new foams have smaller cell sizes leading to significantly lower surface resin uptakes of the sandwich core in resin infusion processes. The mechanical properties of the new foams are excellent and even better than those of the common heat resistant type.

The continuous production of thermoplastic honeycomb cores is a recent development at K.U.Leuven. The production equipment has been improved to deliver high quality material. This equipment is used for the determination of optimum process parameters. This paper describes the production equipment, its development and the experiments that have been done.

This paper presents a technique for the production of graded sandwich cores. A significant failure mode of sandwich panels is the indentation of the foam core in regions at which local forces are introduced into the sandwich panel. The aim of this work is to synthesise a microstructure that can diminish this failure mode. By applying a rapid prototyping technique a periodic, open beam structure has been synthesised. Additionally the structure has been graded in the longitudinal direction by alternating over the beam diameter. The obtained structure was joined with aluminium face sheets to form a sandwich beam. The panel was subjected to a three point bending test and the results were compared to a finite element model.

A numerical and experimental investigation of the temperature distribution during the cure process of a composite sandwich panel manufactured from thick thermoset carbon/epoxy prepreg skin layers and a thermally stable closed cell foam core is presented. The temperature distribution at solidification is subsequently determined from the numerical analysis. The results from the numerical and experimental analyses are compared and good agreement is found.

This paper represents the results obtained from the successful ultrasonic developing work performed within the EUCLID RTP3.21 [1] and the JP 3.23 THALES [2] projects. New automated ultrasonic method for large-scale inspection of sandwich structures applied in the marine industry has been developed. On basis of several laboratory and field tests it can be concluded that the method shows great potential in revealing typical manufacturing and in-service defects.

The ultrasonic Air-coupled scanning technique was used to evaluate the quality of sandwich panels. Scans of panels with defects such as debond between skin laminate and foam core, core crack and defects arising from mechanical tests are presented. The air-coupled technique is an easy technique to use since it can be performed directly in atmospheric air.

In this paper, the Fiber Bragg Grating (FBG) sensors are real time employed to simultaneously monitoring the cure process of CFRP composite laminates with and without damage. Furthermore, the NDE of smart composite laminates embedded FBG sensors are performed by using the 3-point bending test.