Residual Stress Analysis in Injection Moulded Polycarbonate Samples

Abstract. The current paper presents results of residual stress measurements in injection moulded polycarbonate samples, which have been processed in various ways to introduce different residual stress states. The hole drilling as well as the ring-core method were used and methodological developments as compared to measurement procedures applied on metallic samples are outlined. In this context the time dependent viscoelastic behaviour of the investigated material as well as temperature fluctuations during testing are of high importance. It is demonstrated that manufacturing parameters, i.e. mould temperature and injection rate, have a significant impact on the resulting residual stress states. A frame made of aluminium was used to induce pronounced tensile residual stresses in the sample by preventing shrinkage. Holes of different diameters were drilled in order to get information at different depths from the surface. Introduction Injection moulding is a widely used manufacturing process for components made of plastics. The process comprises three stages: filling, packing and cooling. Each stage affects the materials properties of the moulded product and contributes to the formation of residual stresses. Many investigations deal with their analysis by testing and/or simulatio

Fatigue and cyclic deformation behavior of non- and boronized austenitic stainless steel AISI 304 at room and elevated temperatures

A thermochemical surface treatment, the powder-packed boronizing process was optimized and then performed on an austenitic stainless steel, AISI 304. Afterwards, boronized specimens were cyclically loaded at ambient and elevated temperatures (350, 550 and 650 °C). Then the results were compared with the behavior in non-boronized condition. Nonstatistically evaluated S-N curves and cyclic deformation curves were investigated and are discussed. It was found that the boronizing process only improved the high cycle fatigue (HCF) properties of the austenitic stainless steel AISI 304 at room temperature. An endurance limit of about 340 MPa was observed in the boronized condition, whereas a fatigue strength of about 300 MPa was detected for the non-boronized condition. However, at elevated temperatures boronizing was not associated with enhanced fatigue performance of this steel

PVP2006-ICPVT11-93303 ENHANCEMENT OF SURFACE PROPERTIES BY LASER PEENING WITHOUT COATING

ABSTRACT Laser peening without coating (LPwC) has been applied to water-immersed materials using a water-penetrable light of a Q-switched and frequency-doubled Nd:YAG laser. Compressive residual stress of several hundred MPa was introduced at the surface of the materials. High-cycle fatigue (HCF) properties were evaluated through rotating-bending or push-pull type testing for an austenitic stainless steel (SUS316L), a titanium alloy (Ti-6Al-4V) and a cast aluminum alloy (AC4CH). LPwC prolonged the fatigue lives significantly, in spite of the increase in surface roughness ascribed to the ablative interaction of laser pulses with the materials

On the Influence of Surface Hardening Treatments on Microstructure Evolution and Residual Stress in Microalloyed Medium Carbon Steel

Gefördert im Rahmen des Projekts DEA