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A new method for generating virtual models of nonlinear helical springs based on a rigorous mathematical model

Michalczyk Krzysztof, Warzecha Mariusz, Baran Robert

Applied Computer Science

2023

Vol. 19, no 2

96--111

This paper presents a new method for generating nonlinear helical spring geometries based on a rigorous mathematical formulation. The model was developed for two scenarios for modifying a spring with a stepped helix angle: for a fixed helix angle of the active coils and for a fixed overall height of the spring. It allows the development of compression spring geometries with non-linear load-deflection curves, while maintaining predetermined values of selected geometrical parameters, such as the number of passive and active coils and the total height or helix angle of the linear segment of the active coils. Based on the proposed models, Python scripts were developed that can be implemented in any CAD software offering scripting capabilities or equipped with Application Programming Interfaces. Examples of scripts that use the developed model to generate the geometry of selected springs are presented. FEM analyses of quasi-static compression tests carried out for these spring models showed that springs with a wide range of variation in static load-deflection curves, including progressive springs with a high degree of nonlinearity in characteristics, can be obtained using the proposed tools. The obtained load-deflection curves can be described with a high degree of accuracy by power function. The proposed method can find applications in both machine design and spring manufacturing.

Variations in fracture energy of concrete subjected to cyclic freezing and thawing

Kosior-Kazberuk M.

Archives of Civil and Mechanical Engineering

2013

Vol. 13, no. 2

254--259

Fracture energy is one of the fundamental parameters representing cracking resistance and fracture toughness of concrete. The paper deals with the effect of internal frost damage on the fracture energy of concrete. The fracture energy value was assessed on beams with initial notches in three-point bend test assuring stable failure of the specimen. It was found, that the internal damages due to cyclic freezing and thawing have a significant effect on variations in fracture energy, related to changes in destructive load value as well as in deformability of material. The analysis of load-deflection curves obtained made it possible to fit the simple function, describing the post-peak behaviour of concrete subjected to frost damages, which can be useful for the calculation of GF value. It was proved that it is reasonable and feasible to study the freeze-thaw damage process of concrete using fracture mechanics methods.