Elongation criterion
The elongation criterion is a general failure criterion for quasi-isotropic laminates , as they are often used in aircraft construction . It is based on the establishment of limit strains of the laminate in the fiber directions.
application
The laminate to be calculated must be quasi-isotropic. A common layer structure consists of symmetrical 0 °, 90 °, + 45 ° and −45 ° individual layers. The stiffness of the laminate must be known, e.g. B. by applying the classical laminate theory . This allows the expansion of the laminate to be calculated from the external forces and compared with the permissible limit expansion.
restrictions
The elongation criterion is a general criterion, so it can only be used to make a statement about whether a laminate is still intact or not; however, it does not distinguish between different fracture forms, i.e. H. between fiber break and intermediate fiber break . However, an experienced designer will be able to judge the nature of the failure.
The elongation criterion still does not provide any information about which laminate layer has failed.
See also
literature
- Aviation Technical Manual (LTH)
Web links
- CONTRIBUTION TO THE DESIGN AND DESIGN OF 3D REINFORCED FIBER COMPOSITE LOOPS (accessed on December 12, 2019)
- Engineering design with CFRP for bridge construction (accessed December 12, 2019)
- New approaches to the analysis of load transfer and initiation of finite cracks in bonded joints (accessed December 12, 2019)
- Numerical and experimental investigations of the crash behavior of FRP-reinforced metal structural components (accessed on December 12, 2019)