Changing the conceptual design process by developing a solution that gathers load cases from real-life scenarios

Abstract

The graduation project This graduation project was executed for EDS – Casting & Forging B.V. (EDS). EDS (Engineering Design and Supply) is a company which is particularly involved in the designing of products and parts for other companies. These are metal products or parts which are mostly produced by casting. EDS reduces the weight and costs by analysing the relevant load cases and by designing products in a more critical way. EDS wishes to create a product that is able to collect and analyse the loads from real-life scenarios and therefore desires to eliminate the use of safety factors on load cases. Therefore, the assignment of this graduation project was to develop a method or tool that defines and analyses load cases derived real-life situations. At the start of the design process there are many uncertainties, the load cases of which are most critical for optimised design. The problem is that load cases are difficult to come by and an incorrect interpretation yields enormous risk. The current solution is to apply case-specific safety factors of up to a factor of five, this causes the resulting design to be heavier than necessary. EDS has to deal with this problem during the start of a design project. The later in the process, the more expensive it will be. Currently the uncertainties during this stage of the design project are filled in with assumptions for the program of requirements. Which load case and for what scenario is going to be designed is discussed with the client. This scenario should be a real-life scenario where no assumptions are needed since all the relevant values are known. Research made clear that clients tend to base the value of an applied safety factor on their gut feelings. From there the following vision was created: “Too many times a client’s decision is based on gut feelings during the analysis phase of a project. This should be replaced by facts and measured values”. By measuring the real load cases, the client can see what really happens with his product under certain circumstances and will be able to agree on using measured input instead of assumptions supplemented with a safety factor. Research Questions A combination of the company problem, the problem context and a developed vision resulted in the following research question: “How can load cases be gathered from real-life scenarios and how can that change the conceptual design process of EDS?” This question has been divided into three sub-questions to make it more easy to answer. The three sub-questions are: - How could real-life load cases change the concept design process? - How could real-life load cases convince clients to let go of their gut feeling? - How could load cases be gathered from real-life scenarios? To focus primarily on the loads that the particular part/product of a certain project undergoes is chosen as the scope for this project. It will not be necessary to analyse every possible scenario, since the client knows best what happens with his products and is the one who can decide what is acceptable. Fatigue and stress analyses are also out of scope of this project, because they are only relevant when the loads are known already. The solution Three types of hardware were analysed in order to develop a tool that is able to gather load cases from real-life scenarios. These types were load cells, accelerometers and strain gauges. Supported by a program of requirements, the strain gauges were chosen as the most suitable hardware for further development of the measuring tool. To answer the first two sub-questions, a future vision for EDS was developed. This future vision includes a new workflow and a future scenario. In this workflow is showed how the measuring tool changes the design process and in the scenario is explained how this tool convinces clients to let go of their gut feeling. With the strain gauges as starting point, a new measuring method was developed. The final concept is based on the kind of load cells that are made with strain gauges. Step by step this concept was developed based on mechanics theory and tested by SolidWorks simulations and real-life tests. Eventually the results of these tests made clear how sensitive and accurate the measuring method is. A case study was done in order to give an example of what the result could be if this measuring method is going to be used to gather real-life load cases. Further development will be needed in order to solve some limitations, but eventually this method will result in a more responsible way of using raw materials and huge cost reductions.