Materials models and simulation tools are necessary in order to eliminate trial-and-error loops during the development of materials, components and manufacturing processes, to illustrate complex load scenarios and to make reliable predictions of the behavior of existing materials and components as well as for those in the process of development.
For the most part the Fraunhofer IWM obtains the relevant material properties experimentally, determines the associated model parameters and develops methods and algorithms. Material properties are predicted in virtual test laboratories, alongside the safety and service life of components. Process simulation is used to match manufacturing parameters and tools to assure optimum component properties. The Fraunhofer IWM describes corresponding deformation, damage, fracture and function behavior for materials and models mechanisms on the macro, micro, meso and nano scales under load for components or material systems such as solid bodies, fluids, powders and composites.
The competence spectrum of scientists at the Fraunhofer IWM ranges from quantum mechanics and molecular dynamics to computational physics and from homogenization methods to continuum models. In the areas of continuum mechanics, material theory, fracture mechanics and thermodynamics we describe the behavior of materials on the macroscopic scale all the way through to manufacturing processes and component properties. This includes problems of a multi-field nature: examples might include materials under thermo-mechanically or thermo-electrically coupled load conditions.
What is decisive for significant improvements and innovations in the areas of functionality, reliability, life or economic viability is the integral approach or, where applicable, the coupling together of information from different scales and the following of changes in material properties over multiple process steps. Integrated computational materials engineering (ICME) is the tool for quantitively describing the relationships between process steps, material microstructure, material properties and component behavior. ICME can be used to track the changes in material properties throughout the entire manufacturing process of the component and then during operation, and to describe those changes in numerical terms. On this basis, experts at the Fraunhofer IWM can detect weaknesses in the process chain and during the component lifetime and can remedy these.
Examples of the types of problems that can be solved with ICME include:
The design of materials
The calculation of the microstructure development
Virtual determination of materials data and development of suitable material models
Virtual prediction and real-life pre-adjustment of component features such as freedom from cracks, contour accuracy, service life and crash resistance
Optimization of tools and process steps to improve manufacturing yield
For our simulations we use both commercial and in house-developed software. We use the following techniques in our simulation approach:
Finite element, finite difference and finite volume methods
Mesh-free methods such as the discrete element method
High throughput screening
Materials models are available for metals, ceramics, glass, composite materials, semiconductors and biological materials. These include micromechanical models for predicting ductile damage in metals, models to depict the behavior of metals and plastics both at high deformation speeds and under creep stress, and brittle fracture models for high-strength steels, cast materials, ceramics, glass, silicon and composite semiconductors. We describe the following mechanisms at the atomic, microstructural or macroscopic scale: deformation, wear, hardening, fatigue, crash, creepage, aging, damage, failure, piezo effects, diffusion, migration, phase formation and microstructure development. We use high-throughput methods to efficiently find new materials.
For the simulation calculations we use a high-performance computing cluster.
Quantum mechanical calculations and atomism
Microstructure property relationships
Probabilistic material simulation
Material behavior under high-temperature conditions
Probabilistic component simulation
Fracture mechanics simulation of components subject to cracking
Component behavior under high-temperature conditions
Behavior of welds
Behavior of joints
Crash simulations of metallic and composite materials and adhesives
Forming and forming process chains
Welding and joining processes
Particles and flow
Granulate-based manufacturing steps (granulate pouring, die pressing, sintering, tape casting)