No abstract

The paper presents a modified method for the non‐linear dynamic stress‐strain curve determination with the use of cushion curves provided by the manufacturers of closed‐cell foams. This method consists of two main stages: stage 1 – the cushion curves transformation to the coordinate system of dynamic stress‐energy density, combined with the cubic b‐spline curve approximation, and stage 2 – development of the dynamic stress‐strain curve considering that the area under the curve is equal to the energy density of a collision. The stress‐strain curves are one of the basic parameters of the foam material models used to describe the collision process, in the modelling environments of finite element method (FEM), e.g. LS‐DYNA. Performed verification consisting in the reconstruction of cushion curves using LS‐DYNA showed that the proposed method of the dynamic stress‐strain curves determination is efficient and effective. Taking into account that access to the stress‐strain curves is hindered (cushioning material manufacturers do not publish them), and the access to charts of cushion curves is easier, the proposed method for determining the stress‐strain curves can relevantly shorten the process of preparing the input data, which are required during modelling of spatial structures using FEM. Copyright © 2016 John Wiley & Sons, Ltd.

In this study, the authors present a model of the inelastic impact of bodies that takes place during handling of unit loads (cubiform parcels). A modifi ed non-linear Kelvin model is proposed, in which the relationships between object strains and elastic and damping forces of the impact are represented by power functions. The results of analytical investigations on the proposed model were confi rmed by experiments consisting in tests of free fall of the load on rigid ground and on elastic beam. The developed model allows the assessment of the infl uence of mechanical properties of loads and conveyor-line defl ection mechanisms as well as impact velocity, on the dynamic forces exerted on the manipulated objects during the impact.

No abstract