Material removal simulation for steel mould polishing

The surface finish of an injection mould influences the quality of the moulded polymer optic parts. In order to improve and control the surface finish of the mould it is important to be able to predict the material removal during the polishing process of this mould. The aim of this work is to predict the material removal during the polishing process, comparing the results obtained from polishing attempts on steel samples and the results obtained from a simulation model. A simulation model is developed with the abrasive wear Holm-Archard equation in ANSYS. This simulation model will help to eliminate the iterative trial and error polishing, therefore facilitating the steel mould production

Simulation and optimisation of the Interior High Pressure (IHP) manufacturing process using the Finite Element Method (FEA)

A thesis submitted in partial fulfilment of the requirements of the University of Wolverhampton for the degree of Doctor of PhilosophyToday, the market for metal working industry is characterised by an increase in parts varieties, a decrease in batch sizes, and an increase in quality requirements. To remain competitive, companies are forced to ensure that their production output complies with the increasing demand for higher productivity, flexibility and safety. Only new production methods and use of simulation techniques can help to achieve this goal. Prototyping tools for the Interior High Pressure (IHP) forming technique are relatively expensive in comparison to conventional sheet metal forming. Prototyping using the trial and error approach (“Real Prototyping”) is time consuming, and hence very costly. Simulation of the manufacturing processes within the production engineering (“Digital Prototyping”) can help to reduce production time and therefore reduce this considerable cost. Simulation of the IHP forming process helps to replace the classical prototyping method. Today the product development time can be reduced by around 30%, and using the simulation technique will reduce the development time even further. With a further development of the simulation technique, which is the main tasks of this work, a further significant reduction of development time is expected. The aim of the presented work is to improve the integration of the hydroforming simulation into the simultaneous engineering process chain. Today the available simulation software packages are difficult to use and implement. The motivation of this work is to develop tools and methodologies for a fast and easy simulation of the IHP forming process. The target group of the work will be small and medium sized companies (SMEs), because of the difficulty and costs involved for such companies to employ a specialist for the simulation of hydroforming processes. A further aim of the work is to identify the limitations of the process and of the simulation (if there is a difference). The work was subdivided into four main topics. The first covered a thorough investigation to identify and select the best and most suitable material model to use in the hydroforming simulation, which included the best geometric configurations for tools and punches. The second topic covered the development of knowledge about the design of load-curves. This knowledge is then used to create diagrams and formulas with which the load-curves are then applied easily and quickly. The third topic was the development of a graphical user interface (GUI) for the hydroforming simulation. This GUI was integrated into the FE software package ANSYS, and hence, enables the user to create the input files of the IHP forming process simulation easily and quickly. The user is only required to define the major parameters, most of these parameters are available for the user to select through menus. The developed software automatically defines all other necessary parameters. Furthermore a software program to post the simulation results back into the CAD system was developed. This tool creates a link between the initial design process and the final output stage of virtual prototyping, and hence, allows the comparison of various stages within the forming process, as well as the ability to adjust the process parameters as part of the optimisation process. The last topic was the validation of the developed methodology and software. The capability of the developed system by applying it to two concrete applications. The results of the real forming process were compared to the virtual forming results. Within this chapter the different material models offered by the simulation program LS-DYNA and the influence of an anisotropic material (tube) properties were also compared

Large deformation of metallic hollow spheres

Hollow sphere structures are a new group of advanced lightweight materials for multifunctional applications. Within the scope of this paper, the uniaxial deformation behaviour in the regime of large deformations is investigated. Appropriate computational models are developed to account for the deformation mechanisms occurring under high deformations. Macroscopic stressstrain curves are derived and the influence of different material parameters is investigated