/PERTURB/FAIL/BIQUAD

Block Format Keyword This option can be used to study the robustness of a design by generating different failure values for every shell element using the failure model. The random noise scale factors can have either a normal (Gaussian) distribution or random distribution.

Format

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
/PERTURB/FAIL/BIQUAD/ID
perturb_title
F_Mean Deviation Min_cut Max_cut Seed Idistri
fail_ID parameter              

Definitions

Field Contents SI Unit Example
ID Perturb identifier.

(Integer, maximum 10 digit)

  
perturb_title Perturb title.

(Character, maximum 100 characters)

  
F_Mean Mean value of the random noise scale factor.

(Real)

  
Deviation Standard deviation for the normal distribution Only used when Idistri = 2.

(Real)

  
Min_cut Minimum value for random noise scale factor. Must be entered when using Idistri=1, random distribution.

If random value is < Min_cut, random value is replaced with Min_cut.

(Real)

  
Max_cut Maximum value for random noise scale factor. Must be entered when using Idistri=1, random distribution.

If random value is > Max_cut, random value is replaced with Max_cut.

(Real)

  
Seed Seed used for random noise generation. 3
= 0 (Default)
For each run, a random (different) seed value is calculated and written in the Starter output file.

(Integer)

 
Idistri Distribution type.
= 0 (Default)
Set to 2
= 1
Random distribution
= 2
Normal (Gaussian) distribution

(Integer) 4

 
fail_ID Failure model identifier.

This ID must match the /FAIL/BIQUAD, fail_ID, that the perturbation is applied to.

(Integer, maximum 10 digits)

  
parameter Parameter identifier.
c3 (Default)
Failure strain in uniaxial tension.
For example take c3 for /FAIL/BIQUAD model.

(Character, maximum 20 characters. Starting at any location in the input field)

  

Comments

  1. Two computations with the same values, Seed will return exactly to the same results. Currently the only valid parameter is c3 in /FAIL/BIQUAD.
  2. Due to discretization, the random noise in the model will not exactly match the input random noise values. However, the model’s actual random noise values are calculated and output in the Starter output file.
  3. Seed is an integer used to initialize random number generation for the random noise. The Seed can be changed to study sensitivity or model robustness. If Seed=0, a random (different) seed value is calculated for each run and written to the Starter output. To rerun an analysis with Seed=0, use the Seed value written to the Starter output in the original analysis as input in the analysis rerun.
  4. If Idistri = 1, the distribution of the scale factors will be random.
    If Idistri = 2, the normal distribution of the scale factors will have the following probability density function.

    perturb_density
    Figure 1.
  5. This option is only available for shell elements.