This set of Finite Element Method Multiple Choice Questions & Answers (MCQs) focuses on “Plane Trusses”.

1. Plane trusses are also known as _____

a) One–dimensional trusses

b) Two-dimensional trusses

c) Three-dimensional trusses

d) Poly dimensional trusses

View Answer

Explanation: Truss elements are two- node members which allow arbitrary orientation in XYZ co-ordinate system. Truss transmits axial force only. Planar truss is one where all members and nodes lie within Two dimensional plane.

2. A truss structure consists only ___ force members.

a) Only one

b) Two

c) Three

d) Poly

View Answer

Explanation: Truss elements are two node members which allow arbitrary orientation in XYZ co-ordinate system. Truss transmits axial force only, in general, three degree of freedom element. A truss structure consists only 2 truss members.

3. Plane truss element can be shown in _____

a) Local coordinate system

b) Global coordinate system

c) Local and global coordinate systems

d) Dimensional structure

View Answer

Explanation: Truss is one where all members and nodes lie within two dimensional plane. Truss is that elements of a truss have various orientation. These different orientations can be shown in local and global coordinate system.

4. The truss element is a _____ when we see it in a local co-ordinate system.

a) Three dimensional

b) One dimensional

c) Two dimensional

d) Thermal component

View Answer

Explanation: Truss is one where all members and nodes lie within two dimensional plane. Truss is that elements of a truss have various orientations. When we see a truss in local co-ordinate system, the element of a truss can be seen as one dimensional element.

5. Where l and m are direct cosines, then transformation matrix L is given by ___

a) \(\begin{bmatrix}l & 0 \\ m & 0\\0 & l\\0 & m \end{bmatrix}\)

b) \(\begin{bmatrix}l & 0 \\0 & m \end{bmatrix}\)

c) \(\begin{bmatrix}l & m \end{bmatrix}\)

d) \(\begin{bmatrix}l & m & 0 & 0\\0 & 0 & l & m \end{bmatrix}\)

View Answer

Explanation: The direct cosines l and m are introduced as l = cos θ and m=cos ф. These direction cosines are the cosines of the angles that the local x’-axis makes with the global x-, y- axes.

6. Formula for direct cosine l=cosθ= ______

a) x_{2}-x_{1}

b) \(\frac{x_2}{l_e}\)

c) \(\frac{x_1}{l_e}\)

d) \(\frac{x_2-x_1}{l_e}\)

View Answer

Explanation: A truss is a two node element which allows arbitrary orientation in XYZ co-ordinate system. Planar truss is one where all the members and nodes lie within two dimensional plane.

7. The direct cosine m is given by formula cosф= ____

a) \(\frac{x_2-x_1}{l_e}\)

b) \(\frac{y_2-y_1}{l_e}\)

c) \(\frac{x_1-y_1}{l_e}\)

d) \(\frac{x_2-y_2}{l_e}\)

View Answer

Explanation: The direct cosines l and m are introduced as l=cosθ and m=cosф. These direction cosines are cosines of the angles of that local x’- axis makes with global x- and y- axes. Let (x

_{1},y

_{1}) and (x

_{2},y

_{2}) be the co-ordinates of nodes 1 and 2.

8. Strain energy (U) in global co-ordinates can be written as ____

a) q^{’ T} k^{’}q^{’}

b) q^{’ T} k^{’}

c) k^{’} q^{’}

d) \(\frac{1}{2}\) q^{’ T} k^{’}q^{’}

View Answer

Explanation: Strain energy is defined as the energy stored in the body due to deformation. Strain energy per unit volume is known as strain energy density and the area under stress- strain curve towards the point of deformation.

9. The stress σ in a truss element is given by ____

a) σ=E

b) σ=ε

c) σ=E_{e}ε

d) σ=α

View Answer

Explanation: Stress is a physical quantity that expresses the internal forces that neighboring the particles of a continuous material exert on each other. Expression for element stresses can be obtained by noting that a truss element in local co-ordinates is simple two- force member.

10. In a truss element, element temperature load is ___

a) θ^{e}=E_{e}A_{e}

b) θ^{e}=E_{e}A_{e}ε_{0}

c) θ^{e}=E_{e}A_{e}ε_{0}\(\begin{Bmatrix}l \\ m \end{Bmatrix}\)

d) θ^{e}=E_{e}A_{e}ε_{0}\(\begin{Bmatrix}-l \\ -m \\l\\m\end{Bmatrix}\)

View Answer

Explanation: In a truss, temperature effect is arised then thermal stress problem is considered here. Since the element is simply a one dimensional element when viewed in local co-ordinate system, the element temperature load in the local co-ordinate system.

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