Due to the increasing number of traffic accidents involving the collisions of vehicles with the emergency-stop-area head walls in tunnels, a comparative numerical analysis in accordance with the EN 1317 standard has been performed in order to assess the quality of the available protective safety barriers. Based on the simulation results, the values of the relevant injury criteria the Acceleration Severity Index (ASI), the Theoretical Head Impact Velocity (THIV) and the Post-Impact Head Deceleration (PHD) were computed for several collision scenarios involving two different passenger vehicles colliding with two different safety barriers in various ways. The results show that due to the geometrical restrictions in the tunnels emergency stop area none of the barriers can provide total protection for the occupants of the vehicle in the event of a collision. The installation of a steel-sheet-tube crash cushion was, however, found to provide the best possible protection within the given limitations. The results of the analysis were the basis for selecting a safety-barrier design for existing tunnel installations and for the proposed changes in regulations governing the geometry of the tunnels emergency stop area.
F.08 Development and manufacture of a prototype
COBISS.SI-ID: 13216027Objective To evaluate stability and integrity of bi-layer and three-layer collagen-hydroxyapatite (C-HA) osteochondral scaffolds in a human cadaveric knee exposed to continuous passive motion (CPM) with and without loading and the role of added fibrin glue to improve the press-fit fixation of C-HA scaffolds. Design Osteochondral lesions (2.0 x 1.5 cm) were chiseled out on both condyles and trochlea in eight human cadaveric knees. A total of 24 bi-layer (5 mm, four in each condyle) or three-layer C-HA scaffolds (8 mm, eight in the trochlea, four in each condyle) were first press-fit implanted and underwent testing with CPM, 90 cycles, 0°-90°. The second set of 24 scaffolds was implanted in cleaned lesions with the addition of fibrin glue. Two knees with fibrin glue fixation were additionally exposed to 15 kg loading, with 30 cycles of CPM, 0°-30°. Then, the knees were reopened and the scaffolds were evaluated using semi-quantitative Drobnic and modified Bekkers scores. Results All but two scaffolds remained in the lesions site throughout CPM. Two implants failed: both were bi-layer osteochondral scaffolds, press-fit implanted at the lateral femoral condyle (LFC). A statistically significant difference was obtained between press-fit and fibrin glue implants with both Drobnic (2.9 +- 0.7 vs 4.3 +- 0.1, P ( 0.0005) and Bekkers (3.3 +- 1.0 vs 5.0 +- 0.1, P ( 0.0005) scores. Additional knee loading did not affect fibrin glue scaffold fixation or integrity. Conclusion This cadaveric study showed fibrin glue notably improved bi-layer or three-layer C-HA scaffold press-fit fixation regardless of lesion location. It is therefore recommended that fibrin glue be used during surgery to improve early post-operative C-HA scaffold stability and integrity.
F.21 Development of new health/diagnostic methods/procedures
COBISS.SI-ID: 31248857In the production of small-scale in-wheel motors for niche markets, it is necessary to perform various mechanical analyses which enable appropriate geometric design of sufficiently robust structures which can withstand mechanical and thermal loads during operation. Since analyses are complex in every aspect, implementation of appropriate procedures and methods is necessary for rational performance of analyses in numerous structure variations. The procedures include appropriate abstractions or simplifications of geometrical models for numerical (FEM) strain-stress analyses as well as modal and spectrum analyses and explicit mechanical analyses (dynamic loading in a time period – impact loads during vehicle motion). As part of the assignment, more than 20 models and procedures for three fundamental implementations of in-wheel motors were prepared and studied with several variations of geometrical and structure details. The obtained results have confirmed the appropriate procedure and enable the required accuracy and robustness.
F.17 Transfer of existing technologies, know-how, methods and procedures into practice
COBISS.SI-ID: 13912347For press DA-1000 with maximum load of 1,954 t or 19,168 kN, strength analysis of the press framework and weld analysis was performed based on the FE method and in accordance with standard EN 1993-1-8:2005 (EUROCODE 3). The material used for the welded framework of the press is S355JR according to EN 10025-2. Numerical analysis of the framework of press DA-1000 based on the FE method confirmed the appropriateness of load-bearing pillar dimensions and also clearly indicated that the stress values at the point of the vertical weld between cylinder mounting plate and the pillar approximate to or even exceed the maximum static and pulse strength of the material. However, the weld is under compressive loading due to which the load would despite potential plastic strain of the critical weld point expand to a broader area. Under work load, the load-bearing structure of press DA-1000 on most loaded weld points exceeds the maximum levels of cyclic loading of 500,000 cycles (based on method Eurokod 3). With sufficient weld quality (class 2 according to SIST ISO 10721 and group B according to DIN EN 25817) and due to compressive loading of critical weld points, it is safe to say there is a 95% probability the load-bearing structure would withstand 300,000 cycles of work loading.
F.17 Transfer of existing technologies, know-how, methods and procedures into practice
COBISS.SI-ID: 13433627As part of general renovation and modernisation of the 5.500 mm carousel lathe Kolomna, type 1563, reconstruction analysis was performed of key elements of main power transmission gearbox (SMM d.o.o. DN 419497; drawing No. 19497.01.2.002.00). The original propulsion motor of the lathe turntable (changed characteristics) was replaced with a modern frequency regulated asynchronous electric motor (FREM). The increased speed of the new engine also increases the speed of transmission elements. Therefore, it was necessary to examine the lifetime of the new bearings and gear pairs as well as verify these elements according to the applicable standards, which introduce new control procedures with particular emphasis on thermal loads which are increased due to the increased speed of new FREM. Also performed were kinematic and dynamic analyses of complete transmission as well as shaft, gear pairs and bearings analysis based on applicable modern standards and other advanced sources for analysis of machine elements and the proposed changes in the gearbox within geometric and operational restrictions.
F.17 Transfer of existing technologies, know-how, methods and procedures into practice
COBISS.SI-ID: 13912091