Verification of function and service life

A central component is material characterization to determine material properties, which are used in combination with numerical simulation methods to predict function and service life. Simplified mathematical models and the finite element method (FEM) are used for the computational verification of fiber composites and bonded structures, from which polymer-specific material models and modeling techniques can be derived. With the support of the affiliated materials testing laboratory, material maps can be created for FEM programs, enabling material- and application-specific design of bonded joints and components.

Numerous methods and procedures are available at Fraunhofer IFAM. Here you will find a first introduction:

• Targeted material and component development through computer-aided material simulation
• Endurance properties and aging resistance
• Accredited materials testing laboratory
• "Non-Metallic Materials Testing" in the aviation industry according to Nadcap

Targeted material and component development through computer-aided material simulation

The combination of findings from simulations and analytical investigations provides valuable information on alternative strategies and optimization potential in material development. By computer, expected material properties can be predicted much more efficiently in advance of new developments for adhesive and paint formulation, for composites, for surface technology and for nanotechnology.

The simulation of physical and chemical interactions at surfaces and interfaces as well as the mechanical behavior of materials and components is becoming increasingly important as an powerful tool.

The computational simulations with the methods of "Computational Chemistry", provide a valuable contribution to a more targeted material development. The use of quantum chemical, molecular dynamic, Monte Carlo and mesoscopic simulation methods forms the basis for understanding the molecular structure of materials and thus the backbone of computational materials development.

For the design of polymeric materials, methods are used that describe the special, time- and temperature-dependent properties. With the support of the accredited materials testing laboratory, material maps for FE programs can be created and service life calculations performed at Fraunhofer IFAM.

Computer-aided material simulation thus enables the properties of functionalized surfaces, polymeric materials, and their interactions to be predicted, thus providing a valuable contribution to material innovations.

Endurance properties and aging resistance

The aging of polymeric materials in coatings, bonded joints or composites is a well-known phenomenon and, in addition to manufacturing defects, determines the service life of a component. Therefore, understanding aging processes in bonded joints is of economic interest. Despite many years of research, only few of the aging mechanisms are known. Knowledge of these aging mechanisms can help predict the aging of materials or find strategies to delay aging, thereby increasing the safety and service life of products. Test equipment for all common methods of accelerated aging is available to elucidate damage and better understand aging mechanisms to provide information on the durability of materials and components. This includes storage at elevated humidity, temperature and thermal cycling as well as UV resistance and resistance to a wide range of media. In addition to this phenomenological testing, the chemical and physical reactions that occur during degradation are investigated. For this purpose, various spectroscopic and chemical methods are used to detect, for example, the formation of radicals or hydrolysis products and their further reactions during polymer degradation.

Accredited materials testing laboratory

Fraunhofer IFAM has a materials testing laboratory accredited to DIN EN ISO/IEC 17025:2005 and certified to DIN EN ISO 9001:2000-12.

Electromechanical testing machines up to 120 kN with equipment for simulating climatic and environmental influences are available for determining material, adhesive, and bonding characteristics. Single-axis and multi-axis servo-hydraulic testing machines up to 400 kN enable the measurement of the vibration and fatigue strength of components as well as adhesive-bonded and hybrid joints.

Simultaneous exposure to temperature, humidity and corrosive media is also possible. For the measurement of fine strain, the laboratory has incremental displacement transducers, clip-on strain transducers and strain gauges as well as optical, non-contact 1D - 3D measuring systems, with which spatially resolved measurement is also possible.

Test equipment for test speeds up to 10 m/s enables the testing of adhesive and hybrid joints under high load speeds (crash) in the temperature range from -60 °C to 120 °C.

The facilities are used for the experimental simulation of temperature-stress time histories of adhesive and combined joints during production.

"Non-Metallic Materials Testing" in the aviation industry according to Nadcap

In the aviation sector, special regulations and specifications exist with regard to the reliability, reproducibility and traceability of production processes and test methods in order to meet safety requirements. In order to meet these requirements in a comparable manner, the central aviation companies, including Airbus, Boeing, Bombardier, MTU and Rolls-Royce, have organized themselves since 1990 within the Nadcap program (National Aerospace and Defense Contractors Accreditation Program) and defined uniform boundary conditions and prerequisites.

Parts of the Fraunhofer IFAM laboratories have been recognized as independent testing laboratories under the Nadcap system required by the aerospace industry. In our testing portfolio, the G1C method according to AITM 1-0053 is recognized according to the corresponding Nadcap accreditation "Non-Metallic Materials Testing" (NMMT). This means that Fraunhofer IFAM, as an independent laboratory, is able to carry out corresponding tests in the field of aerospace in accordance with Nadcap and to certify this. This means that Fraunhofer IFAM's customers can use the results obtained directly for the development of flying materials.

More about Nadcap recognition at Fraunhofer IFAM