The fundamental understanding of friction has been improved via micromechanical studies of the dual asperity and third body abrasive friction models and a new formulation which accounts for variation of effective contact area and temperature has been developed. It has been shown that wear rate is determined by frictional dissipation rate instead of the term involving the normal pressure as in the classical Archard law and a generalised wear model has been developed which allows treatment of different friction and wear mechanisms coexisting in real contact conditions.
New designs of double piercing test, flat die test, bending under tension with flat dies, bending under tension with wedge-shaped dies and draw bead simulator have been developed.
An efficient link between experimental measurements and computer simulations has been established via an inverse shell. The inverse analyses have been applied to evaluation of hardening parameters in plasticity, estimation of heat transfer coefficients and thermomechanical contact conditions.
Decision support systems based on the finite element method have been developed that are capable of simulating forming processes that include large strains and deformations, frictional contact between workpiece and tool, complex constitutive relations and thermomechanical coupling. Adaptive remeshing techniques and efficient pre- and post-processing have also been provided.
The decision support systems have been applied to the experimental tests and also a number of industrial tests including:-
(i) production of car hood dies
(ii) blanking operations
(iii) cup drawing
(iv) double dogbone forging
(v) crane hook forging
(vi) hot flat rolling
The phenomena of wear have an important influence on the quality of metal forming products and durability of metal forming tools. Therefore they need to be considered in an advanced design and optimization practice in metal forming technology. Wear mechanisms depend on contact conditions such as interface stresses, sliding history, relative velocity, contact temperature, lubricant film thickness, surface roughness and hardness, etc. The interplay of these parameters in forming processes is complex and summation of all contributary effects can not be done intuitively by tool/workpiece designers, especially when complex geometries are considered. However, if the state of the art knowledge from wear micromechanisms is systematically incorporated into a decision support system based on finite element techniques an effective means for quantitative predictions is provided to technology designers. The development of such systems requires interdisciplinary research work involving experts specialised in micromechanical and experimental investigations of wear, numerical modelling, process design as well as tool and product manufacturing. In this project, research efforts will be focussed on the development of appropriate micromechanical wear models and identification or wear parameters by laboratory experiments and inverse numerical analysis. This fundamental knowledge gained in these investigations will be implementated into a finite element based decision support system which will be linked to CAD/CAM facilities. In this way the risk of investment in inappropriate tools and equipment will be reduced, the 'design to product' time will be minimized and the amount of scrap tools and products will be reduced.
Funding SchemeCSC - Cost-sharing contracts
39600 Maliano (Cantabria)