Brannmotstanden til fiberkompositter etter slagskade : Numerisk analyse med beregning for å se endringen i kapasitet til fiberarmerte kompositter under høy temperatur etter at det har blitt utsatt for en slagskade

Abstract

Fiber reinforced composites have many good properties, but also many applications that make it vulnerable to accidental loads, like impact damage and fire. The problem with this is that minor and larger damage can be difficult to observe and a challenge to inspect on the spot. All materials exposed to fire, or high temperatures will expand, which can cause instability and large deformations. Several studies have examined the behavior of composites under these typical accidental loads individually, but none or very few have investigated when they occur simultaneously or the overall effect they provide. To address the problem in this thesis, it has been done a numerical computation in ANSYS APDL, and created a spreadsheet in Mathcad. Analyzes and calculations have been made by varying the impact load, equivalent to a hole with the same reduced capacity as in a impact damage. Measures were taken around the hole, both at room temperature and with a temperature rise of 150 degrees Celsius at a given load. Capacity was measured at one-axial tensile load combined with temperature load. The results showed both reduced stiffness and strength, which reduced fire resistance to the material under a standard fire with several minutes. The reduction of capacity showed a harmonic curve of strength, but greater discrepancies regarding stiffness. To get a better understanding and graphical curve of the results, a nonlinear analysis should be performed along with experiments, where you vary with smaller intervals. It should also be checked for compression capacity, different fiber orientation and possibly bending moment of the laminate when it is part of a sandwich element.