Friction modelling in sheet metal forming simulations: application and validation on an U-Bend product
The accuracy of sheet metal forming simulations strongly depends on, amongst others, friction modelling. The industrial standard is to use the Coulomb friction model with a constant coefficient of friction. However, it is known that the true friction conditions are dependent on the tribology system, i.e. the applied sheet material, coating and tooling material, the lubrication and process conditions. In this paper, an approach is presented for friction modelling in sheet metal forming simulations. The approach is applied to the forming of U-bend test parts for varying tribology systems as commonly used in the automotive indus-try. The friction conditions per system are described using a physically-based friction model included in the Triboform Software. Friction in the U-bend simulations are described as a function of local contact pressure, relative sliding velocity and straining in the sheet material. The simulation results are validated using U-bend forming experiments. It is concluded that the numerical prediction of the punch force magnitude is highly sensitive to friction. In addition to an overall improvement of the prediction accuracy of stamping simulations by including friction modelling, this approach enables to model friction and the effect of varying tribology systems on the final stamped part quality.
Closed-loop control of product properties in metal forming
Abstract Metal forming processes operate in conditions of uncertainty due to parameter variation and imperfect understanding. This uncertainty leads to a degradation of product properties from customer specifications, which can be reduced by the use of closed-loop control. A framework of analysis is presented for understanding closed-loop control in metal forming, allowing an assessment of current and future developments in actuators, sensors and models. This leads to a survey of current and emerging applications across a broad spectrum of metal forming processes, and a discussion of likely developments.
Concentrated solar energy in materials processing
Solar energy, which is available in abundant in nature, is least utilised. As per primary energy product, solar energy conversion can be of three different ways: solar fuels, solar electricity, and solar thermal systems. These three approaches are presently not being fully utilised. Concentrated solar energy (CSE) is an alternative to other types of energy for modifying the surfaces of metallic materials. Attempt has been made to overview the current status of CSE in materials processing technology. In this paper, applications of CSE through solar furnace and Fresnel lens for hardening, coatings, sintering, nitriding, synthesis and welding are discussed.