Uncertainty Quantification in the Comparison of

0 downloads 0 Views 2MB Size Report
May 16, 2018 - circumstances under which solid materials under the processing of external loads .... slope at A were determined as shown below d2v dx2. =.
Yaşar Yanık (UNESP)

16/05/2018

1 / 30

Uncertainty Quantification in the Comparison of Structural Criterions of Failure Yaşar Yanık

Advisor: Samuel da Silva Co-Advisor: Americo Barbosa da Cunha Junior Universidade Estadual Paulista - UNESP Faculdade de Engenharia de Ilha Solteira Departamento de Engenharia Mecânica

Ilha Solteira, SP

Yaşar Yanık (UNESP)

16/05/2018

1 / 30

1

Introduction

2

Objectives

3

Maximum Entropy Principle

4

The Stochastic Explanation for the Simple Deflection Problem

5

Probabilistic design results

6

Conclusion and Future Work

Yaşar Yanık (UNESP)

16/05/2018

2 / 30

Introduction

The aim behind failure theory is the investigation of predicting the circumstances under which solid materials under the processing of external loads A model can have uncertainties on its forecasts, because of conceivable wrong presumptions made during its originations

Yaşar Yanık (UNESP)

16/05/2018

3 / 30

Objectives

A critical comparison between the Tresca and Von Mises failure criterions Uncertainty quantification Monte Carlo Simulation Parametric probabilistic approach Probabilistic design in ANSYS APDL

Yaşar Yanık (UNESP)

16/05/2018

4 / 30

Stochastic Explanation for Failure Criterions

The stochastic version of the stress tensor "

σ=

σx τxy τxy σy

#

Where the parameters σx and σy are the normal stresses and τxy is shear stress respectively. In this part of the work, the value of σy is given as 2 Mpa

Yaşar Yanık (UNESP)

16/05/2018

5 / 30

Stochastic Explanation for Failure Criterions

Afterward, random values are used by applying uncertainty quantification method considering τxy and σx . These values were examined in the the non-standard experimental distribution graph considering Maximum Entropy Principle and the σ values were obtained. |[σ] − λI|υ = 0 According to this equation, λ1 and λ2 eigenvalues were obtained.

Yaşar Yanık (UNESP)

16/05/2018

6 / 30

Stochastic Explanation for Failure Criterions In this equation that represents how to obtain stochastic version of the equation of safety factor for Von Mises and Tresca failure criterion. σvm =

q

(σ2 − σ1 )2 + σ21 + σ22

Fs(V onM ises) =

Fs(T resca) =

Yaşar Yanık (UNESP)

σe σvm

σe σ2 − σ1

16/05/2018

7 / 30

Results and Discussion Considering Two Uncertainties 2.5 VonMises - Histogram VonMises - PDF Tresca - Histogram Tresca - PDF

Probability Density Function

2

1.5

1

0.5

0 1.5

2

2.5

3

3.5

4

4.5

5

F s (Safety Factor)

Yaşar Yanık (UNESP)

16/05/2018

8 / 30

Results and Discussion Considering Two Uncertainties

Yaşar Yanık (UNESP)

16/05/2018

9 / 30

Maximum Entropy Principle

px (x) is probability density function of the Maximum Entropy Principle. According to stochastic equivalent of the approximation, it is also assumed that support, µ (mean) and σ (variance) of the random variables are known px (x) = eλ0 e−λ1 x−λ2 x

Yaşar Yanık (UNESP)

2

16/05/2018

10 / 30

Maximum Entropy Principle

According to Maximum Entropy Principle, the stochastic equivalent of the approximation shown below Z +∞ −∞

px (x)dx − 1 = 0

Z +∞ −∞

Z +∞ −∞

Yaşar Yanık (UNESP)

xpx (x)dx = µ = 0

x2 px (x)dx − µ2 − σ 2 = 0

16/05/2018

11 / 30

Maximum Entropy Principle

0.025

Pdf (probability density function)

Generated Theoretical

0.02

0.015

0.01

0.005

0 120

140

160

180

200

220

240

260

280

300

Normal stress (kpa)

Yaşar Yanık (UNESP)

16/05/2018

12 / 30

Examination of Simple Deflection Problem Considering Uncertainty Quantification

Yaşar Yanık (UNESP)

16/05/2018

13 / 30

The Stochastic Explanation for the Simple Deflection Problem

The stochastic version of equation of the elastic curve and deflection and slope at A were determined as shown below M( x) d2 v = 2 dx EI

M(x) = F (L − x)

Yaşar Yanık (UNESP)

16/05/2018

14 / 30

The Stochastic Explanation for the Simple Deflection Problem If the equation multiplying both members by the constant EI and integrate considering variable x, the equation will be obtained as shown below EI

1 dv = FLx − Fx2 + C1 dx 2

We now observe that at the fixed end B we have v(0) = 0 and θ = dv/dx = 0. Substituting these values into this equation and solving for C1 , then the slop function is determined as shown below EI

Yaşar Yanık (UNESP)

dv 1 = FLx − Fx2 dx 2

16/05/2018

15 / 30

The Stochastic Explanation for the Simple Deflection Problem if the equation integrating both members of the slop function considering at B we have x = L , y = 0. Then the stochastic version of equation is determined as shown below 1 1 EIv = FLx2 − Fx3 + C2 2 6 if the value of C2 carrying back into the deflection function, then the stochastic version equation of the deflection function is determined as shown below   1 3 1 1 2 FLx − Fx v(x) = EI 2 6

Yaşar Yanık (UNESP)

16/05/2018

16 / 30

The Stochastic Explanation for the Simple Deflection Problem

The Hooke-Lamé’s Law in Cartesian Coordinates is shown below         

σx σy σz τxy τxz τzy





        =      

Yaşar Yanık (UNESP)

λ + 2G λ λ 0 0 0 λ λ + 2G λ 0 0 0 λ λ λ + 2G 0 0 0 0 0 0 G 0 0 0 0 0 0 G 0 0 0 0 0 0 G

        

εx εy εz γxy γxz γzy

        

16/05/2018

17 / 30

The Stochastic Explanation for the Simple Deflection Problem The eliminated equations of Hooke-Lamé are determined as shown below h

σx

i

h

τxy

=

i

h

λ + 2G

=

h

G

ih

ih

ξxx

γxy

i

i

Afterwards, the slope function at x = L will be equal to displacement εx . dv 1 = ξx = dx EI

Yaşar Yanık (UNESP)



1 2 FL 2



16/05/2018

18 / 30

The Stochastic Explanation for the Simple Deflection Problem The shear (G) and lambda (λ) modulus are determined as shown below λ=

νE (1 + ν)(1 − 2ν)

G=

E 2(1 + ν)

Also, moment of inertia of the cantilever beam is determined as shown below Z Z +h/2 bh3 I = y 2 dA = y 2 dy = 12 −h/2

Yaşar Yanık (UNESP)

16/05/2018

19 / 30

The Stochastic Explanation for the Simple Deflection Problem

Table: Parameters used in Hooke-Lamé’s equation in a deterministic way.

E[P a] 210 ∗ 109

Yaşar Yanık (UNESP)

ν 0.3

h[m] 0.025

b[m] 0.05

L[m] 1

σe [P a] 5 ∗ 109

16/05/2018

20 / 30

The Stochastic Explanation for the Simple Deflection Problem 0.025

Pdf (probability density function)

Generated Theoretical

0.02

0.015

0.01

0.005

0 150

200

250

300

350

400

Force (Newton)

Yaşar Yanık (UNESP)

16/05/2018

21 / 30

Results and Discussion for Simple Deflection Problem

4 VonMises - Histogram VonMises - PDF Tresca - Histogram Tresca - PDF

Probability Density Function

3.5 3 2.5 2 1.5 1 0.5 0 1

1.2

1.4

1.6

1.8

2

2.2

2.4

2.6

2.8

3

F s (Safety Factor)

Yaşar Yanık (UNESP)

16/05/2018

22 / 30

Results and Discussion for Simple Deflection Problem

4.5

Convergence of F s (Tresca)

4

3.5

3

2.5

2 0

1000

2000

3000

4000

5000

6000

7000

8000

Number of Samples

Yaşar Yanık (UNESP)

16/05/2018

23 / 30

Probabilistic design results

Yaşar Yanık (UNESP)

16/05/2018

24 / 30

Probabilistic design results

Yaşar Yanık (UNESP)

16/05/2018

25 / 30

Probabilistic design results

Yaşar Yanık (UNESP)

16/05/2018

26 / 30

The comparison between results of Ansys and Matlab

4

5 VonMises - Histogram VonMises - PDF Tresca - Histogram Tresca - PDF

4.5

Probability Density Function

Probability Density Function

4

VonMises - Histogram VonMises - PDF Tresca - Histogram Tresca - PDF

3.5

3.5 3 2.5 2 1.5

3 2.5 2 1.5 1

1 0.5

0.5 0

0 1

1.2

1.4

1.6

1.8

2

2.2

F s (Safety Factor)

Yaşar Yanık (UNESP)

2.4

2.6

2.8

3

1

1.2

1.4

1.6

1.8

2

2.2

2.4

2.6

2.8

3

F s (Safety Factor)

16/05/2018

27 / 30

Conclusion

The critical comparison between Von Mises and Tresca failure criterions The stochastic model of the problem The probability density function and a convergence graphic about Von Mises and Tresca failure criterions considering two uncertainty The description of simple deflection problem considering uncertainty quantification The results of simple deflection problem considering uncertainty quantification in ANSYS APDL

Yaşar Yanık (UNESP)

16/05/2018

28 / 30

Future Work

For future work it is going to be studied about the comparison of failure criterions with examination of the frame of formula car in ANSYS APDL Presentation of experimental examples and comparison between deterministic and experimental results considering Von Mises and Tresca failure criterions

Yaşar Yanık (UNESP)

16/05/2018

29 / 30

Acknowledgments

Thank you very much for your attention! Yaşar Yanık (UNESP)

16/05/2018

30 / 30

Suggest Documents