finite element analysis interview questions1 Define: finite element method.ans A numerical technique for finding approximate solutions of partial differential equations (PDE) as well as of integral equations.orcomputational technique for determining the distribution of stresses in engineering structures under load.2 Finite element method is an approximate method (true/false). Also justify your answer.3 What are approximating functions?4 What are field variables?5 Name at least four FEA popular packages.ans Abaqus: Franco-American software from SIMULIA,by Dassault ystemes ADINA ALGOR Incorporated ANSA: Adv. CAE pre-processing software 4 complete model build up. ANSYSLS-DYNA6 Define: i. node ii. Element.7 Briefly explain the application of FEA for a stress analysis with an element.8 Compare between FEM and classical methods.9 Compare between FEM and FDM.10 When there are several FEA packages are available in that any need to study this method.11 Discuss the advantages and disadvantages of FEA.12 Explain the concept of FEM briefly and outline the procedure.13 Write the equation of equilibrium in plane stress condition.14 Draw a typical three dimensional element and indicate state of stress in their positive signs.15 Derive the equation of equilibrium in case of a two dimensional stress system.16 State and explain generalized hooks law.17 Explain the term plane stress.A state of stress in which two of the principal stresses are always parallel to a given plane and are constant in the normal direction. 18 Explain the term plane strain.A deformation of a body in which the displacements of all points in the body are parallel to a given plane, and the values of these displacements do not depend on the distance perpendicular to the plane.19 Distinguish between plane stress and plane strain.20 When do you select plane stress / plane strain approximation?ANS Plane strain and Plane stress are two simplification structural models for the modeling of 3D problems, in which:- Plane strain modelling: strain in Z-direction is neglectible- Plane stress modelling: stress in Z-direction is neglectibleFor a beam, plane stress is normally used, assuming that the stress in Z-direction can be neglected;otherwise 3D modelling is advisable.With reference to the element types, for 2D models, quadrilateral elements with quadratic interpolation is recommended.For 3D models, brick solid elements with quadratic interpolation is recommended.21 Write the constitutive equation for the plane stress and plane strain problems.22 Write the standard form of finite element equation.23 Draw bar element and write the stiffness matrix.24 Define DOF.Minimum no of parameters required to define an entity completely in space25 Draw a plane truss element and indicate the truss element.26 What are natural coordinates?27 Define: local coordinates.28 Write the stiffness matrix for the plane truss element.29 Explain the use of element connectivity table.30 State the purpose of element connectivity table.

----------------------------------------------------------------------------------------------------------------------------------FEA + SOM1.what is moment ?Ans: m=f*x2.relation in pure bending casem/i=sigma/y=e/r3.if u want to calculate stress do u want material properties???Ans: in simple cases like beam problems we don't want material property to calculate the stress. the complex problems like other than beam problems,moment m can be calculated from the relation m=eid^2y/dx^2,we can not able to calculate the moment at any point by the applied force for complex problems.4.what are nonlinear fem methods?Ans:nonlinear geometry,material,contact. if the stiffness changes by geometry it is the non linear geometry. if the stiffness changes by material it is the non linear material case. if the stiffness changes due to the contact it is nonlinear contact case.

5.what is nonlinear geometry case??Ans: if the force applied continuously for example wind turbine blades by the application of wind loads the deformation is high,in that case we must not ignore the higher order terms in strain-deflection relation strain=dy/dx+d^2y/dx^2+d^3y/dx^3+---- considering higher order terms are nonlinear geometry case. these higher order terms are called as green's function.6.what are the theories of failures??Ans: 1.max normal stress2.max shear stress3.vonmisses----etc7.why u consider vonmisses stress theory only?Ans:there is a limitations on max normal stress and max shear stress theories---etc. The vonmisses stress theory is derived from energy formulation so it is suitable for all cases and the stresses developed in the real time environment is near to the vonmisses stress.GM1.prrove that m=ei d^2y/dx^22. what is the constituency relation ship???the relation ship between stress starin in 3 dimensional3.what is the slope of stress strain curve after exceeding proportionality limit??Ans: tagential modulus is the slope of the curve in the plastic region of stress strain curve4.MSC NASTRAN1.shell,plate are having How many degress of freedom ??/Ans: shell is having 6 degrees of freedom 3- translational 3 rotational degress of freedomPlate is having 2 rotational 1- traslation degrees of freedmsolid is having 3 traslational degress pf freedom2.what is the shape function??Ans: read the definition from any text book3.

4. how can you solve a cantilever beam problem in fea softwareAns: cantilever beam problem can be solved in 3 ways1. By using beam element having 3 rotational 3 translational degress of freedom-- we will give geometric dimensions in the form as moment of inertia I2. By using shell element---mesh with shell elements and give the thickness in the directionthen solve it for analysis3.By using solid element --mesh with solid elements and apply the boundary conditions.. solve for analysisQ).5. in which method u will get good results from the above 3??Ans:1. By using beam method we can get exact results but this is valid only for beam structures, not valid for complex structures.2. in the case of irregular sections, complex strcutures the shell element method is the best method because it allows 6 degress of freedom3. using solid elements we can get results but the results are not correct. because it allows only 3 degress of freedom.Q).6.in the case of shell element procedur how the stress is calculated??Ans:in the finite element formulation the stress is calculated throught out the thickness at a node point .i.e integration from -t/2 to t/2 it will calculate

Mechanics - Strength of Materials - Stress - Strain Curveo Stress Strain Curve

1. What is true strain & engineering strain?a. Engineering strain is ratio of change in length to the original length.True strain is defined as the natural logarithm of instantaneous length to original length.

2. What is the area under stress-strain curve?a. Strain energy per unit volume

3. How many constants are required to describe stress strain relationship for a linear elastic isotropic material?a. Two Youngs modulus and Poissons ratio.

4. What is yield point?a. The stress at which plastic deformation starts is called as yield pointPosted byRamickeyat8:03 PM

MechanicsMechanics

1. What is a simple harmonic motion?a. The periodic motion of a body in which acceleration is always directly proportional to the displacement and acts in the opposite direction

2. If mass of the bob of simple pendulum is doubled; what will be the change in its time period?a. It will remain same. Time period of simple pendulum is independent of mass.

3. Newtons Second law gives F = Mass * Acceleration. Can we apply this to a system where is mass is changing?a. Yes. Newtons second law states that force exerted on a particle is equal to the rate of change of linear momentum with respect to time. Hence we can apply it for the cases where mass is not constant.

4. Newtons Second law gives F = M * a in translation. What will be the equivalent equation in rotational motion?a. Torque (T) = Inertia ( I ) x Angular acceleration ( )

5. What will be the Kinetic energy of a rolling body?a. Rolling is a combination of translation and rotational motion. Hence,

KE = * M V2 + * I 2= Translational KE + Rotational KE

6. What is angle of repose?a. Angle of inclination of the surface at which the object placed on surface overcomes the static friction and just begins to slide. Numerically, it is equal to the angle of static friction.

7. What is radius of gyration?a. It is the distance between axis of rotation and a point at which whole mass of the body is supposed to be concentrated so as to give same mass moment of inertia about axis of rotation.

8. What is inertia force?a. As per Newtons first law of motion; inertia is the tendency of the body to maintain its state of rest or uniform motion unless acted upon by an external unbalanced force. The force required to alter this state of body is inertia force.

FEA Question 4Is stress dependant on material?My answerNO stress is not dependent on material,its only depends on force per unit area.

FEA Question 5What is Hookes law? Write down the formula.stress by strain=e

FEA Question 6When a bar (fixed at one end) is acted upon by a force, how do you determine the elongation?A) Deflection can be found by pl^3/3ei ( simple maclay method)

Define finite element methodA numerical technique for finding approximate solutions of partial differential equations (PDE) as well as of integral equations. Or .Computational technique for determining the distribution of stresses in engineering structures under load.