Material Selection for Innovative Design of Automotive Component

Abstract

Increased interest in obtaining fuel efficiency and lower costs led researchers to look for automobiles materials that would lead to these desired goals. The current study assessed three innovative materials for an automobile chassis: magnesium, carbon fibre, fibreglass. The aims of the study are;

1. Investigate three innovative materials; magnesium, fibreglass, carbon fibre, to design an automobile chassis.
2. Analyze the three materials for impact on cost and environment using the lifecycle analysis model.
3. Analyze the chassis’ quality and its impact on the entire automobile product using an innovative material in the design.

Various methods were used to achieve these aims, including Ashby’s selection method of mechanical material, cost analysis, and life cycle analysis for assessing environmental impact. Based on the results of these three methods, a single material is decided. The results show that carbon fibre and glass fibre are possible solutions based solely on cost analysis. However, The LCA results provided a clear picture. According to the LCA results, all materials produced a lesser negative impact on the environment than chassis built from traditional steel. However, carbon fibre produced the least harmful results depending on the environmental impact percentage on eight different variables. Therefore, carbon-fibre is recommended as a material for chassis design.

Acknowledgements

I want to thank my supervisor that this dissertation would not be possible without their constant advice and time. The support and love of my family pushed me to strive for the best in completing this dissertation. I want to thank my professors and university for providing me with the opportunity of conducting this research.

INTRODUCTION

Technological advancements and increased interest in protecting the environment promote the need to advance and upgrade inventions to meet the current age challenges. Innovative car concepts are increasingly becoming needed to solve the international conflict of public and private mobility while also increasing environmental efficiency and decreasing critical carbon dioxide emissions. Customer demand for automobiles has changed to high performance, size, extra comfort that enhances the weight spiral has caused automobile companies to respond by producing electric car concepts (Davies 2012). These new electrical cars have caused a shift towards lightweight design to keep up with increased public awareness of fuel consumption and stricter legislative regulations on carbon dioxide emissions in the UK and worldwide. Experts have found that 100 kg saved on the mass of cars results in the 9 grams of reduction in CO₂ per kilometre (Thiruvengadam et al. 2016). Therefore the reduction of vehicle mass is considered imperative in terms of being the most effective means of reducing CO₂ emissions while maintaining performance, driving quality, and safety.

It is the selection of materials that ultimately influences an automobile’s design, resulting in its price and impact on the environment. Car companies worldwide are looking for ways to make the product more affordable while factors such as oil dependence, stricter environmental laws, and restrictions of GHG emissions are fueling the need for alternative power systems in cars. According to Ribeiro et al. (2007), global energy consumption can be reduced significantly if cars are made lighter in weight at least an average of 500 kg can be achieved. Studies have found other alternative materials that can replace steel bodies such as duralumin, fibreglass, carbon fibre, and carbon nanotubes. The chassis plays a crucial role in developing car production as it holds the importance of housing the engine and the drive train. The current study looks to analyze three such materials as potential replacements for steel in commercial vehicle chassis. Thus, the current study’s research question is as follows;

What will material for a chassis frame for an automobile be the most cost-effective and environmentally friend without compromising quality?

Research Aims

To achieve the answer to the research question stated above the following set of aims and objectives have been devised.

1. Investigate three innovative materials; magnesium, fibreglass, carbon fibre, to design an automobile chassis.
2. Analyze the three materials for impact on cost and environment using the lifecycle analysis model.
3. Analyze the chassis’ quality and its impact on the entire automobile product using an innovative material in the design.

Research Objectives

The following are objectives of the current study;

1. Analyze materials (i.e. magnesium, fibreglass, carbon fibre) based on:
   • Cost
   • Recyclability
2. Analyze the manufacturing process involved in producing the material in terms of the least negative impact of the manufacturing process on the environment and cost.
3. Analyze the impact of the material based on fuel efficiency based on mass reduction of vehicle.

INVESTIGATION

The literature review indicates that there is a need for more research into the process of selecting and selection innovative materials of chassis. Based on the literature review key factors were highlighted on the impact they have on the variety of equipment for an automotive component. There is a need to examine these factors. There seem to be no relevant studies that particularly examine these factors about magnesium, carbon fibre, and fibre-glass as material alternatives for specifical chassis.

The approach for assessing these materials in light of the following characteristics;

• Cost-effective
• Reduces costs
• Reduces effect on the environment

These characteristics will be analysed using a research approach that combines that analysis of Ashby’s steps to material selection, a cost analysis, and Life Cycle Analysis (LCA).

Ashby’s Approach to Material Selection

A material parallel to the stated characteristics previously is conducted using selection criteria outlined by Micheal F. Ashby in Materials Selection in Mechanical Design (Ashby 2011a; Ashby 2011b). The selection strategy chosen includes the following steps to determine the best innovative material for a chassis;

1. Material attributes
2. Selection strategies
3. Translation
4. Screening (Attribute limitations)
5. Ranking (Material Indices)
6. Documentation
7. Local conductions

Based on this strategy presented by Ashby (2011), the selection procedure for finalising the innovative material for a chassis will be similar. It will contain the following steps;

• Translation and deriving the material index as evident in Fig. 1: reinterpreting the design requirements in terms of function, constraints, objectives, and free variables (Ashby 2011b).
• Screening; Appling attribute limitations: Deriving attribute limits from the constraints and applying them to isolate a subset of viable materials (Ashby 2011b).
• Ranking material based on indices on charts: Ordering the viable candidates by the value of the material index, the requirements of excellence that maximise or mitigate some performance measure (Ashby 2011b).
• Documentation of selections: This step includes looking for documentations for the top-ranking choices, it explores the aspect of their history, their established uses, their behaviour in their relevant environments, availability, and more. This documentation phase continues until a more appropriately detailed picture is built of the final choice (Ashby 2011b).
• In addition to the steps of selections outlined by Ashby (2011), the life cycle analysis/assessment method will also be used to select the material based on its impact on the environment, overall cost, manufacturing/production, and longevity.

Life Cycle Analysis (LCA)

The LCA methodology is used to assess the new innovative car component materials through their respective life cycle to evaluate the corresponding environmental impact. Using this model, the research can verify if the material has a lower environmental load and in which phases it contributes the most to the global environmental impact. Davies (2012) the LCA is an imperative tool that needs to be used for guiding the environmental design improvements in the automotive industry. Raghuvanshi et al. (2015) define the LCA as a quantitative evaluation of ecological aspects, including GHG emissions, energy consumption, and acidification. The process consists of the following phases illustrated in Fig. 2 that will be implemented in the current study;

1. Development phases: assess materials.
2. Production phase: assesses components and complete car.
3. Use phase: assesses fuel/electricity of production and production of a product
4. Recycling phase: assesses the process of chains of valuable materials.

Figure 2: LCA Model

Before the LCA is conducted, it is imperative to specify boundaries by deciding the processes that need to be examined. To evaluate the environmental aspects and potential effects linked to the chassis’ material from raw material acquisition to final product disposal, an LCA methodology based on International Organisation for Standardisation (ISO) will be used (van der Harst et al. 2014; Liamsanguan & Gheewala 2008). For this particular reason, the need for the LCA software SimaPro 8.2.0 arises. The software allows the researcher to access the problem-oriented approach CML 2 baseline 2000 to assess the material component’s environmental impact.

The purpose of the LCA under this study will be to identify options for improving the car component’s environmental performance under its more innovative material (Inaba et al. 2010). The results of the assessment can be used for product and process development by automotive companies. This will allow manufactures to analyse the impact of changes in the process, meaning the technology, inputs, and production composition as a whole on the environment (Domenech et al. 2014).

RESULTS

Life Cycle Analysis Results

The LCA had been performed using the SimaPro software. Based on the model for LCA outlined in Fig. 2, the results have been broken down. The energy consumption through each scenario’s lifecycle with a chassis made from the three chosen materials can be seen in Fig. 3. Regardless of the material used, the energy consumption was most in the use phase of the life cycle. This is most likely due to the petrol consumption in this specific phase with the chassis installed into a standard mid-size vehicle. Based on the analysis, the use phase contributes to 65% of the total energy consumption through the whole lifecycle. During the materials’ production phase, the energy consumption is much less for Mg than both fibre-glass and carbon fibre. The production of the mid-size car phase shows an increase in energy consumption due to the higher content of plastic and steel in the production sub-processes and the longer distances travelled. Lastly, the LCA recycling phase has negative energy consumption due to the environmental benefits that result from steel sub-components, individual material component recycling. However, the total energy consumption observed through each of the materials is 9.74 MJ/component for Mg, 10.14 MJ/component for carbon fibre, and 10.2 MJ/component for fibre-glass; this consists of mostly renewable energy.

Figure 3- Life cycle energy consumption for Materials

The LCA also determined the amount of hypothetical solid waste products from each of the phases for the selected materials, illustrated in Fig. 4. Surprisingly the solid waste generated in the use phase is considered negligible compared to that of the material production phase and product production phase. In the production phase, the Mg is accounted for the most solid waste generation, primarily due to plastics such as POM and EPDM production. The quantity of solid waste generation for each material selection in the final disposal phase or recycling is similar, mainly because of relations to the plastic landfill

Figure 4- Life cycle solid wastes generation for materials

The LCA model also provided us with cumulative life cycle air emissions of carbon monoxide (CO), nitrogen oxides (NO_x), Sulphur oxides (SO_x), and non-methane volatile organic compounds (NMVOC) illustrated in Fig. 5. Emissions regarding these variables are lower than traditional mid-sized vehicles with a steel body and chassis. However, the NM VOC g/component air emissions for Mg, carbon fibre and fibre-glass are negligible. With Mg producing 0.035 g/component of NM VOC, 0.014 g/component produced by both carbon fibre and fibre-glass. Chassis produced by carbon fibre had the least amount of air emissions total than the other two materials under analysis. Carbon dioxide (CO₂) emissions in a traditional steel body and chassis mid-size care productions 416 g/component while alternative materials like Mg, carbon fibre, and fibre-glass production estimate 270 g/component. The proportion of CO2 emissions to energy consumption (Fig. 3) is in agreement caused by the large use of carbon-based fossil fuels such as petrol. Based on these correlations, the use phase accounts for the major leap in life cycle air emissions as they are the variables most related to fuel production and combustion in this phase.

Figure 5- Cumulative life cycle air emissions for materials

The life cycle impact assessment was obtained using the problem-oriented approach CML baseline 2000 with impact categories being defined at mid-levels are presented in the report in Figs. 6, 7, 8, and 9. This method concluded that the use of carbon fibre is environmentally preferable to fibre-glass and Mg, as seen in Fig 6. However, regardless of which material is used, it is still more preferable to use with less impact than steel, which has a 100% impact on all the environmental variables. To break down the impact of the chosen materials on chassis production for a mid-sized car, it was essential to categorise the material’s impact according to its specific step in the LCA cycle. All categories saw the greatest amount of environmental impact during the use phase of each of the materials.

Figure 6- Cumulative life cycle air emissions for materials

It seems that the use phase of the LCA had the greatest contribution to the global environment. This is a critical phase, and specific procedures must be allocated to mitigate this phase’s impact as much as possible, regardless of which material is used. However, analysing the impacts closely, it is evident that an Mg chassis contributes to the greater impact on the environment due to a great percentage of impact on its use phase, as seen in Fig. 9. Carbon fibre chassis produced the least amount of environmental impact in all categories, especially that in the use phase, as illustrated in Fig. 8. Lighter weight may be why carbon fibre is performing better as a material causing reduced fuel consumption, which reduces the negative impact on the global environment.

Figure 7- LCA Impact Results for Fibre Glass

Figure 8- LCA Impact Results for Carbon Fibre

Figure 9- LCA Impact results for Mg

Table 2- Comparison of findings with previous work on the economic competitiveness of composite material and Mg