Flat compression test

Sample between the tools

The flat compression test is used as a method of material testing to determine material properties . The flat crush test is a form of compression test . The primary result of the experiment is the flow curve , from which further parameters can be derived, such as parameters of hardening models.

In the experiment, a flat specimen of length a and height h _{0 is} compressed between two parallel tools. The required pressing force  F and the corresponding specimen height h are determined. By applying Newton's third axiom , the equilibrium of forces between the force generated by the testing machine and the force exerted by the material of the same magnitude can be formulated: ${\displaystyle k_{f}\cdot A}$

${\displaystyle F=k_{f}\cdot A=k_{f}\cdot a\cdot b}$

and solve for the yield stress k _f :

${\displaystyle \Leftrightarrow k_{f}={\frac {F}{A}}={\frac {F}{a\cdot b}}.}$

The yield stress determined in this way becomes the comparison degree of deformation in the flow curve

${\displaystyle \varphi =ln{\frac {h}{h_{0}}}}$

assigned.

A plane change in shape occurs when the tool width b is small compared to the sample length a. Overestimations of the measured forces caused by the unformed sample parts can be reduced by rounding the tools.

With the flat upsetting test, high forming speeds and comparative shape changes can be achieved.

Another variant of the compression test is the cylinder compression test .

literature

Dahl, W .; Kopp, R .; Pawelski, O .: Forming technology: Plastomechanics and materials science . Stahleisen, 1993, ISBN 978-3-514-00402-3 .

• Eckart Doege, Bernd-Arno Behrens: Handbook of forming technology. 3rd edition, Basics - Technologies - Machines, Springer Verlag, Berlin / Heidelberg 2016, ISBN 978-3-662-43890-9 .

Web links

• Internship script: Deep drawing and mechanical parameters (accessed on January 9, 2020)
• Extension of the deformation limits of steel materials in high-speed forming (accessed on January 9, 2020)
• CHARACTERIZATION OF THE STRUCTURAL DEVELOPMENT AND FORMABILITY IN SEMI-HOT FORMING OF STEELS (accessed on January 9, 2020)
• Extension of the process limits of flat clinching (accessed on January 9, 2020)
• Undesired asymmetry in the rolling process an orienting representation through upsetting tests (accessed on January 9, 2020)