Multifunctionality and the demand for improving the properties of construction materials make it necessary to leave the approach of monomaterials and combine them to fabricate composite structures, such as combinations of metals with polymers. This article focuses on metal-polymer-metal sandwich sheets. Bonding is improved using adhesive layers. These sandwich sheets are designed for their mechanical and thermal properties, working capacity and so on. A short background of composites structures, to be used in the automotive and aerospace industry, is presented. Moreover, fabricating processes and forming methods for composites are briefly introduced. Finally, a study of 316L/polypropylene/316L sandwich sheets, manufactured in a roll-bonding process and heating press process, is introduced. Their mechanical behavior and formability by deep drawing are discussed.
IntroductionAspects of environmental protection and recycling are becoming more and more important in our society and are the driving forces for development, especially in the area of aviation as well as automotive and transport. To fulfill the rising demands, ecological standards for new products can be a solution -for example, taking factors such as saving resources, sustainability and recycling as well as functionality, design and others into consideration. Novel materials with new and improved functions engender a high interest in the industrial community.Monomaterials of metals, ceramics or polymers cannot fulfill all the technological requirements for a variety of industrial applications. The activities in physics and chemistry as well as engineering are leading to materials with superior properties -often by combining monomaterials to hybrids. 1 Some industrially applied composite materials can be classified as follows: Sandwich composites are understood to be multilayered structures. By using these combinations, it is possible to 'tailor' the properties of special components by choosing the accurate combination of monomaterials, thus providing functionality to fulfill the qualified demands on modern materials and structures. 7 As defined by Zenkert, 8 they are a combination of materials with minimum one of higher strength to create a composite with selected lightweight properties. They are represented, principally, by fundamental patterns of two skin sheets, which are thin but of high strength and stiffness. These skins include a relatively thick, low-density core. These sandwich composites are widely used for engineering applications because of the extremely high stiffness-to-mass ratio.Sandwich materials can be formed with numerous skin (e.g. steel, aluminum alloy sheets etc.) and core materials (polymer foils or fiber-reinforced plastics (FRP), with polymer layers being homogenous or structured), and they are often bonded together using an adhesive agent. Because of being quite simple to manufacture using lamination, roll-bonding or heat-press joining processes as sketched in Figure 1, they exhibit a great potential for future use. 9,10 Moreove...