Church bells are exposed to severe loading conditions during ringing, which results in different damage modes due to material wear, fatigue loading, material deficiencies, different clapper-to-bell layouts, etc. As part of the activities of an EU-funded project called Maintenance and Protection of Bells (PROBELL), experimental investigations and finite-element simulations of the local contact between the clapper and the bell were carried out to study the wear-related damage to bells. First a simplified model was built to assess under the laboratory-controlled conditions the consequences of the repetitive impacts between a spherical body made from steel and a flat block made from bronze. After the results of the finiteelement simulations for a simplified model were in reasonable agreement with the measured data a full-scale finite-element model for simulating the repetitive clapper-to-bell strokes was built. The simulations with the full-scale model were performed for variations of the parameters that influence the structural behaviour of the bell and the clapper: the clapper material, the clapper mass, the relative impact velocity of the clapper, the shape of the clapper, the clappers pin support, the clappers impact angle, the clappers guide accuracy, the bells sound-burp thickness and the coefficient of friction between the clapper and the bell. The agreement between the simulated and the measured results and the relation between the local stressestrain state and the damage to the bell in the contact area are discussed.
COBISS.SI-ID: 12166171
The paper presents a comparison of different optimisation methods to estimate material parameters with the method of reverse engineering. Procedures were used to estimate parameters of nonlinear material model. The most appropriate procedure in terms of quality of the parameters and CPU time cost was chosen.
COBISS.SI-ID: 11919899
In the event of a crash involving a motor vehicle, a car seat with its backrest and head support can increase the level of passenger safety. However, the filling material used in the seat and the head support should absorb a large proportion of the kinetic energy associated with the moving passenger during the crash. This filling material is usually made of polyurethane foam. To simulate the behaviour of the seat assembly during a crash the material characteristics of the seat-filling foam should be appropriately modelled. For this purpose, a low-density-foam material model was developed for the finite element analysis. The paper will present an innovative method for estimating the parameters of the low-density-foam material model that is based on a differential ant-stigmergy algorithm. First the differential ant-stigmergy algorithm will be described, which will be followed by its application on the real case. The results will be discussed and the field of application will be presented.
COBISS.SI-ID: 11912731
One of the biggest problems in an R&D process is the acquisition of information about the structure dynamic loads, which are needed to reliably prove the structure's durability. This paper aims to present an innovative method for simulating stationary Gaussian random processes, which is based on the conditional probability density function (PDF) approach. Design/methodology/approach - The basic information on the structure dynamic loads is first obtained by short-duration measurements on prototypes or the structure itself. These data are then used to simulate the expected structure load states during operations. A theoretical background is presented first, which is followed by the application of the method. Findings - The results show that the spectral characteristics of the original and simulated Gaussian random processes are very similar, if the influential range of the conditional PDF is properly chosen. Practical implications - The method can be applied for simulating random loads of structures, and excitations of dynamic systems, for example. Originality/value - The innovative simulation approach could be helpful to engineers in the early phases of the new product development process.
COBISS.SI-ID: 11971867