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Dynamic investigations of multimass discrete-continuous systems having variable moment of inertia are performed. The systems are torsionally deformed and consist of an arbitrary number of elastic elements connected by rigid bodies. The problem is nonlinear and it is linearized after appropriate transformations. It is shown that such problems can be investigated using the wave approach. Some analytical considerations and numerical calculations are done for a two-mass system with a special case of boundary conditions.

The article presents the analysis of the influence of ion implantation on the properties of titanium alloy used in biotribological systems. The object of the study was the titanium alloy Ti6Al4V implanted with nitrogen ions. Tribological model tests were carried out in combination with a sphere with Al2O3 – a Ti6Al4V alloy disc implanted with N+ ions. Experimental friction tests were carried out on pin-on-disc testers in conditions of technically dry conditions and in conditions of lubrication with the Ringer’s solution. The tests on the TRB tester were carried out in a swinging motion, while on the T-01 tester in a sliding movement. Friction coefficient and wear were determined for all tests. Surface morphology testing and chemical composition analyses were performed using the Jeol JSM-7100F scanning electron microscope, equipped with an EDS microanalyzer. Surface geometry measurements prior to and after tribological tests were performed on a Taylor Hobson’s Talysurf CCI contactless optical profilometer. The optical tensiometer was used to determine the contact angles with demineralized water and Ringer’s solution. The tribological tests of the titanium alloy Ti6Al4V lead to the conclusion that implantation of N+ ions results in better tribological properties of the alloy. The best tribological characteristics were obtained for a titanium alloy implanted with nitrogen ions under technically dry friction conditions. The influence of the tribological system on Ringer’s fluid influenced the reduction of coefficients of friction in the oscillating movement (Tribometer TRB) and sliding motion (Tester T-01M). In the case of a oscillating movement, higher wear of the tested friction pair was observed under friction conditions with the Ringer solution lubrication.

Exploring possibilities of modelling deformation of TRIP steel during manufacturing of fasteners was the objective of the paper. Homogenised flow stress model for the investigated steels was determined first on the basis of compression tests. Inverse analysis was applied to eliminate the effect of friction and deformation heating in compression. Possibility of prediction of local strains and stresses accounting for the TRIP effect was investigated next. Representative Volume Element (RVE) and Statistically Similar Representative Volume Element (SSRVE) with TRIP microstructures were developed and subjected to deformation. Transformation of the retained austenite into martensite was simulated. Computing costs of the RVE and SSRVE were compared and it was shown that they are an order of the magnitude lower for the latter. The SSRVE based micro model, which can be attached to the FE code which simulates forging of fasteners, is the main output of the paper.

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