Macromolecular materials and engineering vol:287 issue:12 pages:881-888
Aircraft and aerospace industry as well as medical and automotive engineering continuously develop smaller and lighter system components. Therefore it is not only important to be able to produce micro parts but also to provide properties for dimensioning and design. This paper explains to what extent mechanical properties from the macro-range are also valid for micro structures. Thereby the modulus of elasticity as well as stress and strain at the yield point are regarded as relevant properties for the part dimensioning. Systematic investigations with tensile bars of different size show that the geometry-dependent property changes are obviously not specific for the material classes of amorphous or semi-crystalline thermoplastics, respectively. That is why a single material testing of micro samples is necessary to determine valid properties for this range. On the other hand the determination known from the classic materials science of plastics that lower temperatures as well as higher loading rates lead to a stiffer material behaviour, is also appropriate for the micro range. The measurements prove that the influence of temperature is much higher than the one of deformation rate. The influence of the production conditions on the mechanical behaviour of test specimen made of semicrystalline thermoplastics is demonstrated by using a varied cooling process. the correlation between the resulting different morphological structures and the changes in the mechanical properties is pointed up on the basis of microscopic views.