The manuscript discusses mechanical properties and microstructure of copper before and after the explosive treatment. For this purpose testing of tensile copper specimens before and after explosive treatment has been performed. The experimental measurements have been supported by the 3D optical deformation measurement system (ARAMIS) and infrared thermography. The study shows that the explosive treatment significantly influences the global response of copper throughout the complete loading range. The uniform distribution of principle strain in untreated specimens is replaced by strain localization which appears just after the start of the loading resulting in much lower failure strain.
COBISS.SI-ID: 18561558
The aim of this paper is to study the quasi-static and dynamic compressive crush performance of newly developed in-situ foam-filled tubes (FFTs) made of light aluminium alloys prepared by powder compact foaming technique. By this method, the aluminium alloy empty tube is filled with an aluminium alloy foam during its formation. The axial mechanical crushing behaviour and the failure mechanisms were assessed by uniaxial compression tests coupled with infrared thermography. Results confirm that the in-situ FFTs have a more stable axial crush performance. The results also demonstrate that heat treated aluminium alloy structures ensure high ductility and very good crashworthiness since they deform without formation of cracks during compression, which is a pre-requisite for good and reliable crashworthiness behaviour.
COBISS.SI-ID: 18369814
The forging die used in a hot forming operation on a hydraulic drop hammer is often exposed to high thermal and mechanical loadings where the service life of die insert is mainly limited by wear and surface cracking. The surface of die should thus be appropriately hardened through surface preparation and treatment to reach the required mechanical properties for improved wear and cracking resistance. This paper summarizes an investigation of the plasma nitrided and PVD hard coated hot-forging die insert performance in real industrial environment. The depth of nitrided diffusion layer varied between 190 to 210 um while the depth of hard PVD coating was approximately 2.5 um. The metallographic investigation of the die surface after 6,500 testing forging strokes showed significant surface spalling caused by a number of cracks appearing in the surface coating and underlying diffusion layer. The die insert for penultimate forging operation was the most critical in terms of number of cracks and their length in comparison with the die insert for ultimate forging operation. Comprehensive computational analyses have been used to determine thermomechanical loading in the critical cross sections of forging die. The improved plasma nitriding process for appropriate surface preparation before hard coating is suggested to extend the service life of die insert.
COBISS.SI-ID: 18826006
The paper reports findings of investigating optimal interface material parameters of product handle to improve its ergonomics by increasing the user performance, comfort, and lower the risk of cumulative trauma disorder development. Optimisation methods in combination with the finite element computer simulations of a human fingertip whilst grasping a handle were used to determine an interface foam material with optimal material properties for best mechanical behaviour of the system. A single objective function was defined to determine best material parameters of the interface foam material, which has to remain firm during low grasping forces to provide stability of the product grasp and appropriately deforms when a critical contact pressure is reached to provide higher contact area. This increases comfort and lowers the contact pressure on the hand and thereby the risk of injury development. The optimisation process yielded the optimised foam thickness and its stress-strain relationship for simulated contact of fingertip model grasping a product handle.
COBISS.SI-ID: 18906646
Among many other materials for the reinforcement of composites, technical fabrics are increasingly being used for the same purpose, especially from glass and basalt tows, which have good mechanical properties. During tensile stress these fabrics are elongated in the direction of tensile force, and at the same time they contract crosswise in relation to the action of the tensile force. In this paper the tensile properties of woven fabrics made from glass and basalt yarns were investigated. Measurements were focused on the lateral contraction, according to which Poisson’s ratio can be calculated. For these purposes, an innovative device as an upgrade of the strength tester and samples of fabrics of non-standard shapes (cross and square) were used. Mechanical properties of the yarns from which the fabrics were made were analysed before and after weaving in order to define the impact of weaving on them.
COBISS.SI-ID: 19075094