Foundations in Structural Nonlinearities using Ansys Mechanical - Theory Quiz - Ansys Certifications

Foundations in Structural Nonlinearities using Ansys Mechanical - Theory Quiz

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1 / 45

Which of the following is a characterization of small strain theory?

$\frac{\Delta L}{L}$

$\sigma = E\varepsilon$

$P=-\frac{1}{3}\sigma {_{ii}}$

$\varepsilon = \int \frac{dl}{l}$

2 / 45

Which method is used to calculate the scalar equivalent for force used to check for convergence? Select the best option.

Complete Quadratic Combination (CQC) Method

Direct combination of the magnitude of forces

Rosenblueth (ROSE) Method

Square Root of the Sum of Squares (SRSS) Method

3 / 45

Which are the two contact formulations that satisfy the requirements of enforcing contact numerically?

Euler formulation

Lagrange formulation

Penalty formulation

Large deformation formulation

4 / 45

With regards to frictional contact, choose the statement that best describes Coulomb's law.

Relative sliding between bodies begins only when the applied external force is less than or equal to the product of tangential force and coefficient of friction

Relative sliding between bodies begins only when the applied external force is greater than or equal to the product of normal force and coefficient of friction

Relative sliding between bodies begins only when the applied external force is greater than or equal to the product of tangential force and coefficient of friction

Relative sliding between bodies only ocurs when the applied external force is less than or equal to the product of normal force at the contact interface and coefficient of friction

5 / 45

When considering eigenvalue buckling analysis, why is the point on force-displacement curve at which a structure undergoes buckling called a bifurcation point? Select the best option.

Because it is only used for column-like structures that can buckle to the left or to the right

Because the structure can split in half

Because the actual buckling load is half of this calculated load

Because the structure can buckle in more than one way (two or more equilibrium solutions)

6 / 45

If the objective of the study is to compute a rough estimate of the critical buckling load of a structure, which of these analysis is preferred?

Nonlinear buckling analysis

Linear transient analysis

Linear buckling (eigenvalue buckling) analysis

Full transient analysis

7 / 45

Which of the following is correct for running an Ansys Simulation? Select the best option.

The simulation can only be run both locally or remotely, but not on cloud.

The simulation can only be run on a local laptop/desktop.

The simulation can run locally, remotely or on a cloud.

One should never run a large solution on cloud or remotely.

8 / 45

A dog bone tensile test of polyethylene illustrates which two types of nonlinearites?

Nonlinear Contact

Nonlinear Material

Spin Softening

Large Deformation

9 / 45

Simulation of a snap fit assembly of two parts is best described as which type of nonlinearity

Material Failure

Nonlinear Material

Nonlinear Boundary Condition

Nonlinear Contact

10 / 45

What is the residual deformation in a case of plastic deformation of a metal part?

Elastic deformation after unloading the part

Permanent deformation after unloading the part

Not enough information to answer the question

Recoverable deformation after unloading the part

11 / 45

Which statement best defines strain?

It quantifies the change in stress of a unit material.

It quantifies the change in length of a unit material.

It can only be calculated if material elastic modulus is known.

It only applies to rigid bodies.

12 / 45

Once a ductile metal under a structural load exceeds the elastic limit, it immediately _____. Select the best option.

stops deforming

exceeds to ultimate strength

begins to develop plastic strain

continues to develop only elastic strains

13 / 45

If the surface of the body has oriented texture, then _____.

the friction is zero in the direction of oriented texture

the body cannot slide in perpendicular direction of the oriented texture

the direction of sliding is important to determine the friction between two bodies

the oriented texture does not influence friction between bodies

14 / 45

The "d" parameter in the Mooney-Rivlin Strain Energy expression $\Psi =C_{10}(I_{1}-3)+C_{01}(I_{2}-3)+\frac{1}{d}(J-1)^2$ is inversely proportional to _____.

the deviatoric strain energy

the initial bulk modulus

the initial shear modulus

Poisson's ratio

15 / 45

What is the key difference between small strain and large strain deformation?

Lower-order terms are negligible when deformation is small enough

Higher-order terms are negligible when deformation is small enough

Large strain formulation requires the line search method.

Large strain calculations can be solved faster than small strain.

16 / 45

Which test generates the most accurate characterization of pure shear in a fully incompressible elastomer? Select the best option.

Sample bound between two parallel plates

Planar tension

Equibiaxial tension

Uniaxial tension

17 / 45

For the stress state that is on the yield surface the material is_____. Select the two best answers.

in the plasticity range

in elasticity range

not permanently deforming

permanently deforming

18 / 45

Select the phrase that best describes the nonlinear nature of contact.

Always an open status

A changing status nonlinearity

Always a closed and sliding status

Always a closed and sticking status

19 / 45

Which of the following makes a large strain calculation nonlinear?

The change in the magnitude and direction of loading.

Newton Raphson solution method

Multiple load steps

The presence of higher-order terms in the expression

20 / 45

Which mathematical expression best represents the definition of a stretch ratio as used in hyperelastic material models, where $L$ is the final length in a principal direction, $L_{0}$ is the original length and _____ is the change in original length. Select the best option.

$\left ( \frac{\Delta L}{L_{0}} \right )^2$

$\frac{L}{L_{0}}$

$\frac{\Delta L}{L_{0}}$

$\left ( \frac{L}{L_{0}} \right )^2$

21 / 45

What is the best way to determine if an analysis needs to include large deformation effects?

Only use large deformation formulation when strain components exceed 5%

Calculate with small deformation and large deformation formulas and compare.

Always use large deformation formula to be conservative

Only use large deformation when convergence becomes an issue

22 / 45

With regards to bonded contact, which of the following statements is correct for the normal and tangential force components developed at the contacting interface?

Both force components are zero

The normal force component is larger than tangential force component

Both force components minimize penetration, separation and relative sliding at the interface

The tangential force component is larger than normal force component

23 / 45

Dynamic instabilities occur due to _____. Select the best option to complete the sentence.

uncontrolled loss of energy in the system

uncontrolled increase in the internal energy of the system

uncontrolled increase in the total energy of the system

uncontrolled increase in the kinetic energy of system

24 / 45

Consider a steel dog-bone test specimen under uniaxial tension loading. Initially the relationship between stress and strain ____. Select the two best answers.

can be expressed by Hooke’s Law

is nonlinear

can’t be expressed by Hooke’s Law

is linear

25 / 45

What characteristics most distinguish hyperelastic materials from ductile metals? Select the two best options.

Remains fully elastic

Nonlinear stress-strain response for full range of strain

Linear

Plastic

26 / 45

When the stiffness matrix terms are functions of unknown DOFs, then which of the following is correct?

To solve the equation $\left [ K \right ]\left \{ u \right \}=\left \{ F \right \}$, empirical equations must be established.

The equation $\left [ K \right ]\left \{ u \right \}=\left \{ F \right \}$ can never be solved.

The equation $\left [ K \right ]\left \{ u \right \}=\left \{ F \right \}$ is non-linear and can be solved using the Newton Raphson method.

The equation $\left [ K \right ]\left \{ u \right \}=\left \{ F \right \}$ can be solved using only experimental data.

27 / 45

A designer needs a quick and rough evaluation of the design. As an analyst how would you proceed towards the simulation? Select the best option.

Only a coarse mesh is sufficient

Use a linear model with coarse mesh and mesh refinement in the regions of interest

Solve on a powerful computer with very fine mesh and all the non-linearities

A refined mesh with linear model is the best choice

28 / 45

Why can the expression for Von Mises yield stress

$\sigma_\upsilon= \sqrt{[(\sigma_{xx}-\sigma_{yy})^2+(\sigma_{yy}-\sigma_{zz})^2+(\sigma_{zz}-\sigma_{xx})^2+6(\sigma_{xy}^2+\sigma_{yz}^2+\sigma_{zx}^2)]/2}$

be rewritten in the principal coordinate system as:

$\sigma_\upsilon=
\sqrt{[ ( {\sigma _1}- \sigma _2)^2+( {\sigma _2}- \sigma _3 )^2+( {\sigma _3}- \sigma _1)^2]/2}$

$\sigma_{12}=\sigma_{31}=\sigma_{23} $

$ \sigma_{12}=\sigma_{31}=\sigma_{23} = 0$

$\sigma_{12}=\sigma_{31}=\sigma_{23} =1$

$\sigma_{12}=\sigma_{31}$ and $\sigma_{23} =0$

29 / 45

Local buckling due to weight is noticed along a section of the wall of a large, axisymmetric oil storage tank. You are asked to reproduce the buckling scenario via finite element simulation. Among the options listed, which type of analysis would be best for completing this task?

Nonlinear transient analysis

Modal analysis

Prestressed eigenvalue buckling analysis followed by static structural nonlinear analysis

Linear transient analysis

30 / 45

For a cardiovascular balloon expandable stent application, why is the stent typically made of a ductile metal?

Because of metal elasticity

Because the deformation is NOT permanent

Because of metal plasticity

Because the deformation is permanent

31 / 45

What is the key principle behind the successful tuning of a stringed instrument?

Large deformation

Kinematic Hardening

Spin Softening

Stress Stiffening

32 / 45

Which of the following is correct regarding the first estimate of stiffness when using the Newton Raphson method? Select the best option.

First estimate should be far less than the applied load

First estimate should be far greater than the applied load

First estimate should be equal to the applied load

First estimate does not affect the accuracy of the solution

33 / 45

Which statement is valid for Penalty Formulation for contact?

Some amount of penetration is allowed

Possible over-constraints

Zero penetration is allowed

Computationally expensive

34 / 45

In the von Mises criteria, the expression is composed of the _____ in the principal coordinate system.

relative value of the three normal stresses

absolute value of the three normal stresses

relative value of the three principal stresses

absolute value of the three principal stresses

35 / 45

Most ductile metals under a structural load undergo elastic deformation for strain ranges up to _____. Select the best option.

0.10%

100%

200%

10%

36 / 45

Structural instabilities may occur due to different reasons, but two common ones are due to a loss of stiffness and due to inertial effects. Dynamic instability describes the latter situation. Which of these cases is NOT a dynamic instability?

Aeroelastic flutter

Crushing of an empty soda can

Brake squeal

Excessive vibration of rotating equipment

37 / 45

The process of rolling ductile metals into desired shapes with rigid rollers best exemplifies which of the three types of nonlinearities? Select the best option.

Material nonlinearities

Nonlinear elastic materials

Internal frictional heating

No-separation contact

38 / 45

Select the three types of structural nonlinearities:

Bonded Contact

Large Deformation

Metal Plasticity

Frictional Contact

39 / 45

From the force-displacement curve of an unstable structure in a static analysis, how can one identify the point of instability? Select the best option.

It is the point at which slope of the force-deflection curve decreases.

It is the point at which slope of the force-deflection curve increases.

It is the point at which the slope of the force-deflection curve approaches zero.

It is the point at which the force-deflection curve becomes nonlinear.

40 / 45

Lagrange strain formulation is best characterized as _____. Select the best option to complete the statement.

another form of Hooke's Law

an example of small strain theory

another form of isotropic hardening

an example of finite strain theory

41 / 45

What are the characteristics of Bauschinger effect? Select the three best answers.

Compressive yield stress is reduced after first yielding in tension.

It is important to consider under cyclic loading beyond the yield stress

Can be simulated with kinematic hardening

Can be simulated with isotropic hardening

42 / 45

A nonlinear analysis was performed of an engineered structure in operation, and nonlinear materials were defined. The resulting force-deflection curve showed the response to be linear. Which of the following statements is the most reasonable conclusion that can be made of the analysis?

If the applied loads were doubled, the displacements would also be doubled since the response will always be linear.

The analysis could have also been set up with linear materials and still obtained accurate results.

If the design (i.e., geometry) were modified significantly, a linear analysis should be run on the new design.

The analysis was incorrect since a nonlinear analysis will always result in a nonlinear response.

43 / 45

Which of the following is a method used for solving non-linear response of structure? Select the best option.

Jacobi method

Simpson's rule

Cholesky decomposition

Newton Raphson method

44 / 45

How does the Lagrange formulation enforce contact?

By way of a spring stiffness to minimize penetration

It treats contact as a constraint and enforces zero contact penetration

By equating the normal force component to the tangential force component

By assuming an infinite contact stiffness

45 / 45

Which key material characteristic is necessary for the proper use of equibiaxial tension and planar shear testing? Select the best option.

Small Poisson's ratio

High density

Fully incompressible

Highly compressible

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Private: Foundations in Structural Nonlinearities using Ansys Mechanical

Foundations in Structural Nonlinearities using Ansys Mechanical - Theory Quiz

Total Available Time - 90 mins

Total Number of Questions - 45

Foundations in Structural Nonlinearities using Ansys Mechanical - Theory Quiz