ABSTRACT
A key property in the manufacture of toecaps for protective footwear is resistance to impacts, deformations, and cracking, as the resulting defects may lead to serious workplace accidents involving the lower extremities. The present paper proposes a new approach to qualitative verification of toecap design based on numerical simulations of impact tests. Computational experiments were conducted for toecaps made from different materials (AISI 10450, S235, S355 and A36 steels, as well as Lexan polycarbonate) and characterized by different geometries, which were recreated by 3D scanning. The impact resistance of the toecaps was analyzed using a numerical model simulating an experimental impact test. The results were used to determine the location of critical stresses and to plot equivalent stress maps for the studied toecaps. The finite element analysis of the impact tests was carried out with an explicit elastoplastic finite element code: ANSYS (Ansys, Inc., Canonsburg, PA, USA) with the Explicit Dynamics module of the Workbench solver. The presented analysis of the impact resistance of toecaps by the finite element method for impact simulation may be used to optimize the spatial geometry of toecaps and to verify the construction of toecaps and the material deformations that may occur. In addition, it could eliminate unsuitable materials that are likely to undergo dangerous deformations, and draw attention to the deformation caused by the impact of the toecaps used in footwear in the working environment.
Subject(s)
Lower Extremity , Finite Element Analysis , Computer SimulationABSTRACT
The objective of the present work was to evaluate the effects of different types of particles added to a polymer paste applied onto a textile carrier on the cut resistance of the resulting material. Knitted aramid textile samples were coated in laboratory conditions using a polymer paste that was functionalized with 12 types of reinforcing particles of different chemical compositions and size fractions. Cut resistance was tested in accordance with the standard EN ISO 13997:1999 and the results were subjected to statistical analysis. The effects of additive particles on the microstructure of the polymeric layer were assessed by means of scanning electron microscopy. The type and size of the particles affected the cut resistance of the functionalized knitted fabric. They were also found to change the morphology of the porous structure. Composite coatings containing the smallest additive particles exhibited the best cut resistance properties.
ABSTRACT
The objective of this work was to examine the mechanical strength properties of polycarbonate toecaps designed for commercially available protective footwear, subjected to repeated impacts simulating workplace conditions. The effects of impacts on the toecaps were expressed as the height of toecap clearance, which has a direct bearing on the safe use of protective footwear. Changes in toecap geometry were evaluated using an originally developed methodology taking into consideration the requirements of Standard No. EN ISO 22568-2:2019. Additionally, external and internal sides of toecaps were scanned in three dimensions after each impact and reverse engineering was used to analyze deformations in toecap geometry by comparing the shape of the toecaps before and after impact. Three-dimensional scanning made it possible to measure the remaining safe distance for toes between the footwear sole and the impacted toecap surface, which is an indicator of the protective properties and safety of toecaps during use.
