A computational model for determination of static capacity and fatigue lifetime of large slewing bearings is presented. In the proposed model, contact load distribution along the bearing raceways is calculated on the basis of the static equilibrium between contact loads acting on the raceways, and external loads acting on the bearing. On the basis of the maximum contact force and some typical and experimentally determined material parameters, the static capacity of a bearing is calculated and a comparison of different approaches for a calculation of the fatigue lifetime of a bearing is presented. The following calculation methods are compared: ISO standardised calculation approach, a stress-life approach and a strain-life approach. The presented vector based calculation approach for a calculation of the contact load distribution seems to be an appropriate approach for a fast evaluation of the influence of the bearing clearance and the deformation of bearing rings on the contact load distribution. The comparison of fatigue lifetimes calculated with different calculation methods shows that the choice of method for the calculation of an equivalent mean stress significantly effects the calculated lifetimes. Furthermore, the comparison of lifetimes also shows that, by assuming that ISO standardised calculation approach gives relevant results and provided that material parameters are properly defined, the stress-life approach is, to some degree, a proper method for calculation of the rolling bearing fatigue lifetime.
COBISS.SI-ID: 15354134
This paper addresses numerical and experimental analysis of the m.porer aluminium foam. Numerical models are based on computed tomography data in order to capture the complex material meso-structure. Uni-axial experimental tests were performed for quasi-static loading and an excellent agreement with numerical results has been obtained. Numerical analyses were extended for characteristic strain rates in order to analyse the strain rate sensitivity and anisotropy. Both, the micro-inertia and the base material strain rate sensitivity have an influence on the dynamic behaviour of the cellular metal
COBISS.SI-ID: 15867926
Lotus-type porous materials exhibit some unique anisotropic mechanical and thermal properties which are very useful for a number of industrial applications. This paper evaluates several computational models for determining the compressive engineering elastic modulus and engineering yield stress of lotus-type iron in transversal and longitudinal direction in regard to pore orientation with parametric nonlinear finite element computational simulations for porosities ranging from 0 to 0.65. The considered pore topologies of evaluated computational models are either regular (indirectly reconstructed) or irregular (directly reconstructed). Comparison of computational results, experimental tests and analytical estimations shows good correlation of some evaluated computational models. The simplified porous model with pi/4 rotated aligned regular pores can be recommended for fast computational estimation of lotus-type material behaviour under mechanical loading, when some material parameters for homogenised lotus-type material modelling have to be determined.
COBISS.SI-ID: 16149782
Cellular structures are increasingly being used in modern engineering due to their advantageous properties. However, the behaviour of cellular structures made of brittle materials under mechanical loading is often very unpredictable. This paper reports on an experimental study using different silicone rubber mixtures as pore filler material in an open-cell structure made of photopolymer, FullCure M840, to improve its behaviour under quasi-static and dynamic mechanical compressive loading. The experimental results show that the initial brittle behaviour has been completely stabilized by using the silicone pore filler, resulting in improved mechanical properties and significantly higher energy absorption capability of the cellular structure, thus providing unique material properties which could be adapted for individually optimized applications.
COBISS.SI-ID: 15983894
Existing computer tools for ergonomic design are unable to assist designers with higher level advice within design processes. Thus, design engineers need to rely on their own knowledge and experience when making crucial decisions relating to products' ergonomic parameters. An intelligent decision support system has been developed in order to overcome this bottleneck. This paper presents a knowledge base, containing ergonomic design knowledge specific for hand tool design. A pneumatic hammer handle design is used as a case study in order to show how ergonomic design knowledge built within this system is used to improve the ergonomic value of a product.
COBISS.SI-ID: 15585558