Comparison of the impact analysis performed by finite elements method and test results of the plastic oil pan designed for light commercial vehicles

At the present time, effects of the global warming has started to threaten our lives and future seriously. Because of this reason, it was started to take new measures in order to eliminate factors which cause global warming all around the world. Automobiles are clearly seen as one of the greatest cause of the global warming since their internal combustion engines emit harmful gases such as CO, NOx.Various precautions have been taken in order to reduce or completely remove harmful gases emitted from automobiles. On the one hand, the most important of these is electric cars which no emit any harmful gas while it is working. Electric cars are being studied by the most of car producer. However, because of some limitations on the technology like low battery range, it seems for electric cars to take more time to take place of conventional cars completely. Because of this reason, on the other hand, studies on internal combustion engines and automobiles continuous to produce cars which emit less harmful gases. In order to force car manufacturers to produce more enviromental friendly automobiles, emission regulations are being updated regularly. These strict regulations encourage manufacturers to find solutions for designing more efficient cars. The most important share of improvements on the vehicle and the engine is the introduction of new technologies to increase the efficiency of the engine and weight reduction studies in order to meet new regulations. In the context of weight reduction efforts, it is aimed to design lighter vehicles by using new materials without compromising the strength of the part. The oil sump, which has an important role since it stores engine oil inside, is one of the engine parts included in the weight reduction exercises in the vehicles. Looking at the historical development of the oil pans, it was first seen to be made of cast iron which is heavier than many materials. Subsequently, significant weight reduction has been achived by using aluminum instead of iron. Today, it was started to use deep drawn steel sheet pans in addition to oil pans produced by aluminum casting method. Although the steel material has a higher density than aluminum, it has the advantage of a significant weight reduction due to the lower wall thickness. Finally, for the plastic material that has begun to take its place in many parts of the vehicle, many vehicle manufacturers have begun to work on it and some have started to use plastic sump in their vehicles. Because, plastic material has many advantages such as lower density, higher strength which make them popular in automotive industry. All mechanical parts are designed to fulfill certain requirements such as high strength, high resistance to corrosion, high resistance to temperature etc. Therefore, when material changes are made in the vehicle and engine parts, it should be considered that there will be no reduction in this type of proporties of the parts. In the case of any material change to be made for the oil pans, properties which must be possessed in order to fulfill the function of the pans should be maintained. The most important xxii proporties that oil sump should definitely have is impact strength to stones which may come from road or small rocks located in the roads. The other requirement oil sumps should have definitely is to be resistant to high temperature and corrosion. Until the idea of using plastic material for oil pans, stone impacts were not very critical since both iron and aluminum casting and deep drawn steel materials has good stone impact performance. However, after the idea of using plastic oil pan in order to take advantage of weight reduction, stone impact strength of the sumps started to gain importance. Many plastic material manufacturers has started to develop durable plastic material to be used in oil pans in order to meet automobiles manufacturers' requirements. In this thesis study, the plastic oil pan designed to take the place of the deep drawn steel pan used in light commercial vehicles in the scope of weight reduction has been investigated in terms of the resistance to stones that could come from the road. This study is generally composed of three main sections as literature research, impact analysis and falling weight test. Firstly, some literature research has been performed related to oil pans, mechanical proporties of materials, polymers, composites and stone impact studies on plastic materials and sumps. Secondly, stone impact analysis were conducted on three dimensional model of the plastic oil pan by using the finite element method. Analysis were performed for different wall thickness and rib variations in order to see effects of the these parameteres on impact performance of the plastic oil pans. In addition to this, impact analysis were repeated for different locations which are determined considering to possible impact locations which has higher risk. Besides, all analysis were conducted with two plastic material in order to see material grade effects on the impact properties of the sumps. First material is PA66 GF30 and second material is PA6 GF30. Second material used in analysis has been develop by material procuder to provide more strentgth to oil pans in terms of stone impact. Thirdly, some analysis were replicated in the falling weight test in order to validate the analysis results. The obtained analysis results indicates that the plastic material specially produced for the oil sumps to be had improved impact properties showed higher impact strength than the other material. When ribs variations are investigated, different number of ribs were implemented to areas which has higher risk in terms of stone imapct. it was observed from results that the higher number of ribs positive effect on impact strength. During investigation on wall thickness, wall thickness has been changed as 2.5 mm, 3.5 mm, 4.5 mm, 5 mm respectively. Analysis were conducted on the area which has higher risk than other locations due its position as well. On th analysis results, it was observed that the increase of the thickness of the main wall did not cause a significant improvement in the specially produced material for the oil pans which is called PA6 GF30. For the other material PA66 GF30, the increase in the thickness of the main wall has little contribution to impact strength of the sump. In the scope of the study, finally oil pan design determined to be used according to analysis results has been produced with plastic injection method. Then, falling weight impact test has been conducted to real parts in the test bench specially designed for oil pans in order to enable requested boundary conditions such as impact velocity and angle. Both plastic materials mentioned above has been tested in the falling weight test bench in order to compare with analysis results. In the results of the falling weight test, plastic material specially produced for oil sumps has showed better results than other material unsuprisingly. Test results also are very similar with analysis results for both material with a few exceptions. At the end of the study, taking into consideration the analysis and test results, the serial production decision was taken for material which does not show any serious problem in terms of impact strength with some improvements on weak areas a little more. The conclusions to be drawn from this thesis study are that plastic materials can show different impact performance depending on their grade and finite elements analysis can be used for first evaluation of these materials before the prototype part manufacturing to conduct real tests.