Users:General FEM Analysis/Materials Reference/Puck Failure Criterion
Contents |
General Description
It is based on Mohr‘s fracture hypothesis which is appropriate for brittle fracture behaviour of composite materials. It can distinguish between fibre fracture and different inter-fibre fracture. Both 2D and 3D formulations are implemented into Carat++. Available fracture modes for 2D Puck Criterion are:
- Fibre Fracture (FF)
- Inter Fibre Fracture Mode A (IFF A)
- Inter Fibre Fracture Mode B (IFF B)
- Inter Fibre Fracture Mode C (IFF C)
Available fracture modes for 3D Puck Criterion are:
- Fibre Fracture (FF)
- Inter Fibre Fracture (IFF)
Stresses on the Fracture Plane
Strength Analysis
In order to judge if a stress vector on the stress spce is leading to damage, a mathematical expression is needed. This expression is called fracture condition an is written as the following general form:
: Components of stress vector
Ri. : Strengths under corresponding stresses
F : Fracture function
There are 6 main strengths that should be related to the occurring stress state:
The general form of fracture condition can also be rewritten as following:
F < 1 : no fracture
F = 1 : fracture limit reached and fracture occurs
F > 1 : fracture limit exceeded
with F 
[0,
)
Parameter Description
| Compulsory Parameters | ||
| Parameter | Values, Default(*) | Description |
|---|---|---|
| EF | real | Elasticity modulus of the fibres |
| RTL | real | Resistance to longitudinal tension (Direction 1) |
| RCL | real | Resistance to longitudinal compression (Direction 1) |
| RTT | real | Resistance to transverse tension (Direction 2) |
| RCT | real | Resistance to transverse compression (Direction 2) |
| RSL | real | Resistance to longitudinal shear |
| VFF | real | Volume fraction of the fibres |
| PTTL | real | Inclination parameter,
|
| PCTL | real | Inclination parameter,
|
| Optional Parameters | ||
| Parameter | Values, Default(*) | Description |
| STRESS TYPE | 2D, 3D | Indicates what kind of stress state should be used to calculate the failure condition. When not given, related element’s stress type is taken. |
| NUE12F | real | Poisson’s ratio for fibres. (De f ault = 0.2) |
| MGF | real | Amplification factor (De f ault = 1.2) |
| S, M | real | Parameters necessary for calculation of weakening due to  (De f ault = S = M = 0.5)
|
| PTT | real | Inclination parameter  . When not given, calculated using the strength values. See Section 3.1.2.3
|
| WEAKENING | int | Switch for calculation of weakening due to .
|
| FPS | SWS*, GSS | Switch for fracture plane search algorithm.
|
| FPS_SWS_SIZE | real | Step size for step-wise fracture plane search |
Example of a Complete Input Block
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