Abstract (EN):
This paper discusses some aspects of the finite element prediction of damage growth and fracture initiation in finitely
deforming ductile solids. The material presented is of particular relevance to the simulation of industrial metal forming
operations characterised by the presence of extreme deformations and strains, often resulting in localised material deterioration
with possible fracture nucleation and growth. In this context, we focus on the crucial issues of constitutive
modelling, low order finite element technology for near-incompressibility and adaptive mesh refinement. Constitutive
modelling is treated within the framework of continuum damage mechanics. The effect of micro-crack closure, which
may dramatically decrease the rate of damage growth under compression, is incorporated and its computational implementation
is discussed. The use of low order elements in the presence of high nearly-isochoric plastic strains is addressed
with the introduction of a methodology whereby the volumetric constraint is enforced over patches of simplex elements.
This allows the effective use of simplex tetrahedra¿¿for which intricate contact conditions as well as mesh generation
over complex evolving geometries can be easily treated¿¿without the volumetric locking typically associated with conventional
low order displacement-based elements. With the aim of achieving an effective and robust adaptive strategy
for this class of problems, it is important to design a damage-based error indicator which represents the essential features
of the physical phenomena under consideration. The underlying idea is to correlate the adaptive procedure with
the failure mechanism. The effectiveness of the resulting framework is demonstrated by the solution of relevant
problems.
Language:
English
Type (Professor's evaluation):
Scientific
No. of pages:
34