Mesasuring and testing devices

EXSACOM –Servohydraulic testing field

The facility primarily offers static and fatigue tests on advanced composites pertaining to characteristic damage states, damage tolerance, lifetime assessment and qualification. Extensive experience in several methods of test control, data acquisition, data analysis and sophisticated measurement procedures is available. As an extension of the deformation measuring methods, a fast optical grating measurement system is provided which enables a quantitative contactless measurement of displacement and strain distributions even on curved surfaces. By means of a computer-aided system, which has been well approved over the past years, arbitrary loading sequences can be applied with a special event control. The loading can be immediately influenced in real time by the results of a fast on-line data processing and can be changed dynamically. In addition, the online observation and evaluation of composite damage progress under dynamic loading can be evaluated by special optical techniques. Furthermore, knowledge is available regarding specific verification tests for numerical and analytical models and simulations, particularly pertaining to impact behavior and residual strength prediction.

Technical Details

The testing field is equipped with mechanical testing machines for quasi static tests; up to 200 kN. Tests are conducted under climatic conditions at temperatures between -60°C and 120°C and at defined humidity. In addition, servohydraulic testing machines are provided for fatigue tests and tests under operating loads; up to a maximum of 1,000 kN. During the tests data are collected and evaluated by multifunctional real time control systems. Additionally, special mechanical testing facilities for DCB, ENF and MMB tests can be used as well as an impact facility with impact energies of up to 40 J. Moreover, a grid reflection system for contactless deformation observation and documentation can be offered. Beyond, an optical grating system (Highspeed ARAMIS) is available for fast measurement (up to 4,000/sec) of the 3-dimensional displacement fields. 

Over the past 20 years several servo hydraulic tests were conducted within EU projects: Four ESA contracts for comprehensive studies of composite damage mechanisms, the BRITE EURAM projects ADCOMP (ADaptive COMPosite Delamination Modeling), CUDAMAGE (Cumulative Damage under Service Conditions) and DAMTOS (Damage Tolerant Design of FRP Sandwich Structures), recently the EU projects TANGO, FALCOM and EXSACOM.

During all projects substantial experimental data of advanced composites were collected and evaluated. The results can help improving numerical and analytical modeling of the residual strength and lifetime of such composites, particularly pertaining to impact damage and critical damage progress.

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