Visco-hyperelastic model with damage for simulating cyclic thermoplastic elastomers behavior applied to an industrial component

In this work a nonlinear phenomenological visco-hyperelastic model including damage consideration is developed to simulate the behavior of Santoprene 101-73 material. This type of elastomeric material is widely used in the automotive and aeronautic sectors, as it has multiple advantages. However, there are still challenges in properly analyzing the mechanical phenomena that these materials exhibit. To simulate this kind of material a lot of theories have been exposed, but none of them have been endorsed unanimously. In this paper, a new model is presented based on the literature, and on experimental data. The test samples were extracted from an air intake duct component of an automotive engine. Inelastic phenomena such as hyperelasticity, viscoelasticity and damage are considered singularly in this model, thus modifying and improving some relevant models found in the literature. Optimization algorithms were used to find out the model parameter values that lead to the best fit of the experimental curves from the tests. An adequate fitting was obtained for the experimental results of a cyclic uniaxial loading of Santoprene 101-73

Influence of the material composition SMD diodes on their environmental impact

The influence of the material composition of surface-mount device (SMD) diodes on the environment has been analysed in this research. This impact assessment has been performed by means of an environmental impact calculation through a life cycle assessment (LCA), in which the EcoInvent dataset has been updated and customised, generating a more precise environmental impact analysis by considering the exact material composition provided by several suppliers of diodes and also recycling during the production stage. Considering the EcoInvent diode dataset as a reference, variations from nearly 1640% to only 8.5% of the environmental impact have been achieved. For example, the impact per 1 g of SMD diodes can change the global warming potential from 292 g CO2 eq up to 354 g CO2 eq, whereas for abiotic depletion, values can change from 9.9 × 10-7 up to 1.9 × 10-4 kg Sb eq. The presence of critical raw materials such as antimony, cobalt, or magnesium, together with precious metals as gold or silver, highly influences the environmental impact values obtained, demonstrating the considerable influence on the environmental impact of the material composition of the SMD diodes analysed. © 2021 by the authors. Licensee MDPI, Basel, Switzerland

Textile injection process characterisation by means of a spiral mould

New developments are being carried out within the injection moulding field, such as gas injection, bi-injection, co-injection, sequential injection, compression injection or textile injection processes. These techniques require new developments as they highly modify design and process conditions. In this work, the influence over the plastic material flow of the introduction of different film textiles into the mould is measured. A specific measurement system consisting of a monitorised spiral mould with pressure sensors has been used to measure the influence of different tissues over the mould pressures. As an application of this measurement system, a viscous model is generated to characterise the rheological behaviour of the thermoplastic and textile joint. The viscous model obtained is applied on a conventional CAE tool for the simulation of textile injection pressure results for the different film textiles analysed

LCI databases sensitivity analysis of the environmental impact of the injection molding process

During the last decades, society’s concern for the environment has increased. Specific tools like the Life Cycle Assessment (LCA), and software and databases to apply this method have been developed to calculate the environmental burden of products or processes. Calculating the environmental impact of plastic products is relevant as the global plastics production rose to 288 million tons in 2012. Among the different ways of processing plastics, the injection molding process is one of the most used in the industry worldwide. In this paper, a sensitivity analysis of the environmental impact of the injection molding process has been carried out. In order to perform this study, the EcoInvent database inventory for injection molding, and the data from which this database is created, have been studied. Generally, when an LCA of a product is carried out, databases such as EcoInvent, where materials, processes and transports are characterized providing average values, are used to quantify the environmental impact. This approach can be good enough in some cases but in order to assess a specific production process, like injection molding, a further level of detail is needed. This study shows how the final results of environmental impact differ for injection molding when using the PVC’s, PP’s or PET’s data. This aspect suggests the necessity of studying, in a more precise way, this process, to correctly evaluate its environmental burden. This also allows us to identify priority areas and thereby actions to develop a more sustainable way of manufacturing plastics

A systematic material selection process applied to a luminaire diffuser

This paper presents a systematic material selection process for technical, environmental and economic criteria. This methodology has been applied to the design of a weatherproof luminaire. The materials selected for the production of this diffuser were characterised to obtain their mechanical properties and to perform exhaustive research on impact analysis by means of finite element modelling. Also an economic analysis and an ecological impact assessment have been performed. Thanks to this working methodology, a final design of the diffuser has been developed having the optimum thickness to achieve the mechanical specifications and minimise the environmental impact and the cost of the diffuser

Influence of the composition on the environmental impact of a casting magnesium alloy

The influence of the composition of magnesium alloys on their environmental impact was analyzed. In order to perform a more accurate environmental impact calculation, life cycle assessment (LCA) with the ReCiPe 2016 Endpoint and IPCC 2013 GWP (100 y) methodology was used, taking the EcoInvent AZ91 magnesium alloy dataset as reference. This dataset has been updated with the material composition range of several alloys included in the European standard EN 1753:2019. The balanced, maximum, and minimum environmental impact values were obtained. In general, the overall impact of the studied magnesium alloys varied from 3.046 Pt/kg to 4.853 Pt/kg and from 43.439 kg CO2 eq./kg to 55.427 kg CO2 eq./kg, depending on the composition. In the analysis of maximum and minimum environmental impacts, the alloy that had the highest uncertainty was 3.5251, with a range of ±7.20%. The element that contributed the most to increase its impact was silver. The AZ91 alloy, provided by the EcoInvent dataset, had a lower environmental impact than all the magnesium alloys studied in this work. The content of critical raw materials (CRMs) was also assessed, showing a high content in CRMs, between 89.72% and 98.22%

Conformal polishing approach: Tool footprint analysis

Polishing process is one of the most critical manufacturing processes during a metal part production because it determines the final quality of the product. Free-form surface polishing is a handmade process with lots of rejected parts, scrap generation and time and energy consumption. Two different research lines are being developed: prediction models of the final surface quality parameters and an analysis of the amount of material removed depending on the polishing parameters to predict the tool footprint during the polishing task. This research lays the foundations for a future automatic conformal polishing system. It is based on rotational and translational tool with dry abrasive in the front mounted at the end of a robot. A tool to part concept is used, useful for large or heavy workpieces. Results are applied on different curved parts typically used in tooling industry, aeronautics or automotive. A mathematical model has been developed to predict the amount of material removed in function of polishing parameters. Model has been fitted for different abrasives and raw materials. Results have shown deviations under 20% that implies a reliable and controllable process. Smaller amount of material can be removed in controlled areas of a three-dimensional workpiece

A New Multiparameter Model for Multiaxial Fatigue Life Prediction of Rubber Materials

Most of the mechanical components manufactured in rubber materials experience fluctuating loads, which cause material fatigue, significantly reducing their life. Different models have been used to approach this problem. However, most of them just provide life prediction only valid for each of the specific studied material and type of specimen used for the experimental testing. This work focuses on the development of a new generalized model of multiaxial fatigue for rubber materials, introducing a multiparameter variable to improve fatigue life prediction by considering simultaneously relevant information concerning stresses, strains, and strain energies. The model is verified through its correlation with several published fatigue tests for different rubber materials. The proposed model has been compared with more than 20 different parameters used in the specialized literature, calculating the value of the R-2 coefficient by comparing the predicted values of every model, with the experimental ones. The obtained results show a significant improvement in the fatigue life prediction. The proposed model does not aim to be a universal and definitive approach for elastomer fatigue, but it provides a reliable general tool that can be used for processing data obtained from experimental tests carried out under different conditions

The influence of environmental conditions on the dimensional stability of components injected with PA6 and PA66

The design of assembly components requires special attention to aspects related to their dimensions to ensure their functionality. The goal of this paper is to analyse the influence of case-based environmental conditions, including extreme hydrothermal conditions, on the dimensional stability of a component made from different polyamides throughout the component''s working life. The results support the conclusion that components made from PA6 have a higher capacity to absorb humidity than those made from PA66 and, on the other hand, a higher capacity to lose this humidity, which implies a more significant effect on the average error in the dimensions considered (12% for PA6 in comparison to 3% for PA66). With regard to assembly dimensions, components remain within dimensional tolerances under average and extreme humidity conditions and average temperature conditions. Components injected with P66 are more stable for all of the situations analysed

Environmental impact analysis of the injection molding process: Analysis of the processing of high-density polyethylene parts

This paper studies the environmental impact of the injection molding process by carrying out a life cycle assessment. A review of how EcoInvent''s Life Cycle Inventory database characterizes this process has been conducted, and a new methodology based on that analysis has been carried out. Aspects such as the infrastructure of the factory or waste treatment are part of the environmental impact of the injection molding process, but the most significant factor is electricity consumption; therefore, electricity consumption measurements of the process have been performed. This environmental analysis has been applied to the processing of several parts made of high-density polyethylene, which have been characterized by measuring the electricity consumption. As a consequence of this work, it has been proven that electricity consumption can be used as an injection molding machine selection criteria, from an environmental standpoint, as it produces the highest environmental burden of the process