A FEM-Based 2D Model for Simulation and Qualitative Assessment of Shot-Peening Processes

Shot peening is one of the most favored surface treatment processes mostly applied on large-scale engineering components to enhance their fatigue performance. Due to the stochastic nature and the mutual interactions of process parameters and the partially contradictory effects caused on the component’s surface (increase in residual stress, work-hardening, and increase in roughness), there is demand for capable and user-friendly simulation models to support the responsible engineers in developing optimal shot-peening processes. The present paper contains a user-friendly Finite Element Method-based 2D model covering all major process parameters. Its novelty and scientific breakthrough lie in its capability to consider various size distributions and elastoplastic material properties of the shots. Therewith, the model is capable to provide insight into the influence of every individual process parameter and their interactions. Despite certain restrictions arising from its 2D nature, the model can be accurately applied for qualitative or comparative studies and processes’ assessments to select the most promising one(s) for the further experimental investigations. The model is applied to a high-strength steel grade used for automotive leaf springs considering real shot size distributions. The results reveal that the increase in shot velocity and the impact angle increase the extent of the residual stresses but also the surface roughness. The usage of elastoplastic material properties for the shots has been proved crucial to obtain physically reasonable results regarding the component’s behavior

Investigation of the Shot Size Effect on Residual Stresses through a 2D FEM Model of the Shot Peening Process

Shot peening is a surface treatment process commonly used to enhance the fatigue properties of metallic engineering components. In industry, various types of shots are used, and a common strategy is to regenerate a portion (approximately up to 35% of the total shot mix weight) of used and worn shots with new ones of the same type. Shots of the same type do not have a constant diameter, as it is concluded by experience that the diameter variation is beneficial for fatigue life. The process of stochasticity raises the difficulty for the application of computational methods, such as finite elements analysis, for the calculation of pivotal parameters, for instance, the development of the residual stress field. In the present work, a recently developed plane strain 2D FEM model is used, which has the capability to consider various shot size distributions. With the aid of this model, it became feasible to study the effect of the shot-size distribution, its sensitivity, and to draw conclusions considering the industrial practice of using a mixture with new and worn shots. The diameter of these shot types differs significantly, and a used shot may have a diameter three times smaller than a new one. As concluded from the finite element results, which are verified from experimental measurements, a shot type with a larger diameter causes a wider valley in the stress profile, and the peak stress depth increases. Alongside the peak stress depth movement, with smaller shots, larger residual stresses are observed closer to the surface. Thus, the superimposition of many shots with variable diameters causes the development of a residual stress field with enhanced characteristics. Furthermore, this residual stress field may be further enhanced by adjusting or increasing the percentage weight of the used shots, up to ~50%

Investigation of the Shot Size Effect on Residual Stresses through a 2D FEM Model of the Shot Peening Process

Shot peening is a surface treatment process commonly used to enhance the fatigue properties of metallic engineering components. In industry, various types of shots are used, and a common strategy is to regenerate a portion (approximately up to 35% of the total shot mix weight) of used and worn shots with new ones of the same type. Shots of the same type do not have a constant diameter, as it is concluded by experience that the diameter variation is beneficial for fatigue life. The process of stochasticity raises the difficulty for the application of computational methods, such as finite elements analysis, for the calculation of pivotal parameters, for instance, the development of the residual stress field. In the present work, a recently developed plane strain 2D FEM model is used, which has the capability to consider various shot size distributions. With the aid of this model, it became feasible to study the effect of the shot-size distribution, its sensitivity, and to draw conclusions considering the industrial practice of using a mixture with new and worn shots. The diameter of these shot types differs significantly, and a used shot may have a diameter three times smaller than a new one. As concluded from the finite element results, which are verified from experimental measurements, a shot type with a larger diameter causes a wider valley in the stress profile, and the peak stress depth increases. Alongside the peak stress depth movement, with smaller shots, larger residual stresses are observed closer to the surface. Thus, the superimposition of many shots with variable diameters causes the development of a residual stress field with enhanced characteristics. Furthermore, this residual stress field may be further enhanced by adjusting or increasing the percentage weight of the used shots, up to ~50%

Indirect determination of the mechanical properties of stochastic lattices

Determination of the mechanical behaviour of lattice structures has become a necessity to successfully implement lightweight concepts in various applications. Due to the large surface to volume ratio of these structures, the computational effort required for the FE simulation of models incorporating lattices is significantly increased mainly because of the large finite elements number which are necessary to accurately describe the complex input geometry. In this work a simple solution is employed in order to calculate the stress – strain properties, using a bilinear material law and equivalent bulk geometry. The verification of the FE model is fulfilled through the comparison of the lattice deformation and compressive force between experimental data and FE calculated results. After the verification of the FE model, it was possible to determine the mechanical behaviour of stochastic lattices, for an extended range of the investigated parameters, using only computational tools

Indirect determination of the mechanical properties of stochastic lattices

Determination of the mechanical behaviour of lattice structures has become a necessity to successfully implement lightweight concepts in various applications. Due to the large surface to volume ratio of these structures, the computational effort required for the FE simulation of models incorporating lattices is significantly increased mainly because of the large finite elements number which are necessary to accurately describe the complex input geometry. In this work a simple solution is employed in order to calculate the stress – strain properties, using a bilinear material law and equivalent bulk geometry. The verification of the FE model is fulfilled through the comparison of the lattice deformation and compressive force between experimental data and FE calculated results. After the verification of the FE model, it was possible to determine the mechanical behaviour of stochastic lattices, for an extended range of the investigated parameters, using only computational tools

Recycle of printed circuit boards from waste electric and electronic equipment and their reusability as filler in 3D printed poly(lactic) acid composites

AbstractRecycling raw materials (RMs) from waste electric and electronic equipment (WEEE) and reusing them in additive manufacturing applications, has tremendous benefits, including health risk reduction by landfill decongestion. Furthermore, final composite products are given enhanced properties, increasing their added-value commercialization. The non-conductive substrate of printed circuit boards, composed of glass fibre-reinforced epoxy resin was processed and tested as poly(lactic acid) (PLA) filament additive. Scanning electron microscopy confirmed carbon, oxygen, and silicon as the main elements of the composite. Differential scanning calorimetry of 5% and 10% composites showed that the addition of fillers did not result in a significant change of composite filaments’ thermal properties. 15% filler addition resulted in higher crystallinity and melting point. Rheological analysis showed that composite filaments’ viscosity increased compared to pure PLA (300–400 Pas compared to 100–200 Pas), maintaining their structural strength during printing. Mechanical performance analysis showed that Young’s modulus, flexural modulus, flexural strength, and elongation of the composites increased compared to pure PLA (up to 9.6%, 24.6%, and 28.2%, respectively), enhancing mechanical properties, structural integrity, and load-bearing capacity. The abundance and low cost of RM and the small number of processes, present the upscaling potential, increasing the profit margin in a swiftly growing market