Moos, E., "Light Weight Materials for Aerodynamic, Acoustic and Thermal Management Improvements in Underbody Applications," SAE Technical Paper 2014-01-1036, 2014, doi:10.4271/2014-01-1036.
In today's vehicles underbody parts are absolutely necessary to reach a certain performance level regarding fuel saving, corrosion protection, driving performance and exterior as well as interior noise. With the constant demand for additional parts, which means additional weight on the car, lightweight materials have come more and more into the focus of development work. LWRT (low weight reinforced thermoplastic) is the acronym for this material group. The ongoing success of such materials in underbody applications that compared to compact materials such as GMT (glass mat reinforced thermoplastic) is the weight saving of up to 50 %, or in other words, with LWRT you can cover twice as much surface then with GMT. The production process is compression molding, but with low pressure because LWRT-material needs only partial compact areas, most regions of these parts can have a density even below 0.5 g/cm3. Another advantage coming with the process is the possibility to use multi-cavity tools, so a high volume production becomes very economical. The multilayer structure can be easily tailored to customer specifications regarding stiffness, strength, acoustic performance and other properties. Since LWRT can have an open porous structure, which absorbs noise from both sides of the part (engine side for engine noise and street side for e.g. tire noise), the material has become very interesting to replace existing NVH-solutions such as additional absorbers on the parts.