P. Harnatkiewicz

Study on fatigue cracks in steel-concrete shear connection with composite dowels

In recent years many research on composite beams with innovative shear transmission with composite dowels have been conducted (mainly within PreCo-Beam project [15] ) and innovative composite constructions have been designed and built. As this shear connection is to be applied mainly for bridges, problems concerning fatigue behaviour appear [1] , [16] . Composite dowels behaviour in aspect of fatigue resistance and fatigue cracks investigations is extremely complex. It is caused not only by complicated stress distribution from external loads but also by eigenstresses which are released during beam cutting and cutting technology itself as well. It will be proved in detail macroscopic studies how production and cutting process may influence the fatigue crack initiation and propagation process. This paper presents investigations undertaken after finished PreCo-Beam project [15] which is part of the research to be conducted years 2009–2011 at Wroclaw University of Technology. Results of detailed metallographic inspections of fatigue cracks obtained during full-scale tests, and schedule of next full-scale tests to be performed at Wroclaw University of Technology are presented. Described researches are carried out in order to determine fatigue lifespan of composite beams with shear transmission realized with composite dowels of MCL shape [5] , [10] . MCL shape is currently the most often used shape of steel dowel because of its fatigue behaviour as well as technological aspects of its production process and therefore all foreseen research will focus mainly on this shape. The MCL shape is shown in Fig. 33 , Fig. 34 , Fig. 35 , Fig. 36 , Fig. 37 , Fig. 38 .

The influence of frontal protection system design on pedestrian passive safety

Car-to-pedestrian front impacts have been well described in the papers. However, there is still insufficient data measuring the performance of new type of Frontal Protection Systems (FPS) fitted on Sport Utility Vehicles (SUVs). Therefore, the aim of the studies was to validate the method of the FPS design, complying with the European Commission Regulations. The complete numerical model of the vehicle front with FPS was created and then subjected to a precise pedestrian impactor subtest. The physical experiment results proved good conformity with the outcomes from numerical simulations. Hence, the design of the presented FPS design was a base for legal process such as European Union homologation.

Caterpillar drive shaft damage causes analysis

The paper presents examples of fatigue stress fractures of quarry equipment drive shafts. In order to determine the real cause of this damage, we have performed a detailed analysis of the problem The paper presents the experimental data, numerical analysis and metallographic examination.

Degradation of a geared bearing of a stacker

Large size rolling-element bearings used for turning of upper body of machines used in open-pit mining are made in form of single-row or double-row ball bearings. Section diameter of those bearings may be as large as 20 m and rolling elements have diameters of 100 to 250 mm, while they are under eccentric axial load from few to tens of MN. Due to low stiffness of supportive elements and its non-uniform presence all over the circumference of the bearing, the load upon rolling elements is rather unequal in those bearings. The flow of load stream concentrates in points which are in the areas with highest stiffness. This may be achieved using modern computer-assisted design tools. The specificity of these custom made machines makes obtaining credible data for numeric models possible only by applying analyses of the already existing bearings and their support structures which had been in operation for many years. Was introduced applied to opinion of effect of long-lasting exploitation on change of parameters of bearing.

Damage in the complex low-cycle fatigue

A life prediction approach for a random multiaxial fatigue is proposed in the present paper. D16T aluminium alloy were tested under non-proportional loading (tension-compression, torsion). Cylindrical specimens were tested under different stress controlled trajectories in the plastic range. In additional, numerical method analysis such as finite method – FEM were used in the experiment. The additional damage energy for Al alloy D16T in the middle stabilized (average) cycle during low cycle fatigue for complex non-proportional loading square trajectory was also discussed in relation with fatigue life prediction. The aim of this paper is to examine the non-proportional low cycle fatigue life of D16T aluminium alloy which shows small additional damage stress, and also develop energetically damage model for complex non-proportional stress state during low-cycle fatigue for construction.

Analysis of the Fatigue Fractures in the Eccentric Press Shaft

The paper presents selected aspects of stress analysis of eccentric press. This approach is based on the assumption that fractures can be present in the analyzed constructions. Calculations define the current state of the component with respect to fracture mechanics. Reported research work was performed using analytical, numerical and experimental methods in order to evaluate durability of the considered structural element.