学堂在线材料力学期末考试答案-中南大学
1.单选题 (2分)
For a beam with a concentrated couple,which one of the following is true?()
A
At the point of concentrated couple action, the shearing force diagram and bending moment diagram both have abrupt change
B
At the point of concentrated couple action, there is abrupt change in shear force diagram and no abrupt change in bending moment diagram
C
At the point of concentrated couple action, there is no abrupt change both in shear force diagram and bending moment diagram
D
At the point of concentrated couple action, there is no abrupt in the shear force diagram and there is abrupt change in the bending moment diagram
正确答案： D
2.单选题 (2分)
If the coefficient of equivalent length of the long column is doubled, the critical pressure of the column will be ( ).
A
Doubled
B
Increased by 4 times
C
One half of the original
D
A quarter of the original
正确答案： D
3.单选题 (2分)
The maximum shearing force is FSmax, the maximum bending moment is Mmax and the section width b of the beam with rectangular section remain unchanged. If the height is doubled, the maximum bending normal stress and the maximum bending shear stress are () times of the originals.()
A
0.125,0.5
B
0.25,0.25
C
0.25,0.5
D
0.5,0.5
正确答案： C
4.单选题 (2分)
The fatigue rupture of components is the result of ()
A
The result of the maximum normal stress in the component
B
The result of the maximum shear stress in the components
C
Results of crack formation and propagation in members
D
The equivalent stress value in the component is too large
正确答案： C
5.单选题 (2分)
The ring, with a mean diameter of d, rotates at an angular speed of ω. If in the case of insufficient strength, the right measures can be taken are ()
A
reduce d or ω
B
ω and d remain unchanged; increase size of the section
C
ω remains unchanged; enlarge d
D
d remains unchanged; enlarge ω
正确答案： A
6.单选题 (2分)
When subjected to a pair of forces of equal magnitude, opposite direction, and the line of action coincident with the axis of the member, the deformation of the member is() .
A
Stretch or compression
B
Shear
C
Bend
D
Torsion
正确答案： A
7.单选题 (2分)
The main characteristics of fatigue rupture of metal components under the action of cyclic stress are ()
A
No obvious plastic deformation, the fracture surface is divided into smooth area and coarse grained area
B
No obvious plastic deformation, the surface of the fracture is coarse-grained
C
There is obvious plastic deformation, the fracture surface is divided into smooth area and coarse grained area
D
There is obvious plastic deformation, and the fracture surface is smooth
正确答案： A
8.单选题 (2分)
The figure shows that a cast iron beam with rectangular section. The critical point of the beam is ( ).
2.jpg
A
At point D
B
At point E
C
At point F
D
At point G
正确答案： A
9.单选题 (2分)
Regarding number of cycles-to-failure(fatigue life), which of the following statements is correct ()
A
The number of cycles-to-failure of the component is only related to the material
B
In certain cycle characteristics, the greater the maximum stress in the cyclic stress, the shorter the number of cycles-to-failure
C
In certain cycle characteristics, the greater the maximum stress in the cyclic stress, the longer the number of cycles-to-failure
D
The number of cycles-to-failure of components has nothing to do with the cycling characteristics of cyclic stress
正确答案： B
10.单选题 (2分)
Under the same material conditions, as the flexibility increases, ()
A
The critical stress of the long column decreases while that of the medium flexibility bar remains unchanged.
B
The critical stress of the intermediate column decreases while that of the large flexibility bar remains unchanged.
C
The critical stress of the large and the intermediate column are both decreased.
D
The critical stress of the large and the intermediate column are both unchanged.
正确答案： C
11.单选题 (2分)
An axial compressive force F=Fcr is acting on an ideal column in linear equilibrium. And then the column produces the bending deformation due to a small lateral disturbing force. If the disturbing force is removed at this time, ( ) .
A
The bending deformation will disappear and return to a straight line
B
The bending deformation is reduced and the straight line shape can not be restored
C
The bending state is not changed
D
The bending deformation continues to increase
正确答案： C
12.单选题 (2分)
Four circular shafts with different support conditions as shown in the figure. The diameter and material of each one are the same. The stability of the compressive column in fig.()is the worst.()
7.jpg
A
a
B
b
C
c
D
d
正确答案： A
13.单选题 (2分)
The figure shows that forces of belt on the shaft are F1=3.9 kN,F2=1.5 kN. The diameter of pulley is D=60 cm and the yield strength is [σ]=80 MPa. According to the 3rd strength theory, the diameter of the shaft should be no less than ().
9.jpg
A
43.2
B
46.9
C
50.5
D
59.7
正确答案： D
14.单选题 (2分)
The capacity of a member to maintain its original equilibrium state under external load is the() .
A
Stiffness
B
Strength
C
Stability
D
Toughness
正确答案： C
15.单选题 (2分)
For a simple beam under distributed load, at the middle of the span, which one of the following is true?()
A
Maximum shear force, bending moment equal zero
B
Shear force equals zero, bending moment equals zero
C
Shear force equals zero, maximum bending moment
D
Maximum shear force, maximum bending moment
正确答案： C
16.单选题 (2分)
What is wrong with the following description of internal forces is() .
A
An internal force is an additional interaction between parts of an object caused by an external force
B
The internal forces are continuously distributed throughout the cross section
C
The internal force varies with the external force
D
An internal force is an interaction between particles in an object
正确答案： D
17.单选题 (2分)
When member is subjected to the eccentric loads, the wrong description of neutral axis is ( ).
A
The position of the neutral axis is independent of external forces and eccentricity
B
The neutral axis and the point of the external force are on opposite sides of the cross section centroid respectively
C
The neutral axis is related to the shape and size of the section
D
The closer the external force point is to the centroid, the farther the neutral axis is from the centroid
正确答案： A
18.单选题 (2分)
Two solid torsional circular shafts with different materials are subjected to the same torques,. They have the same diameter and length. What is the relationship between the maximum shear stress and the twist angle? ()
A
The maximum shear stresses are equal and the twist angles are not equal
B
The maximum shear stresses are not equal and the twist angles are equal
C
The maximum shear stresses are equal and the twist angles are equal
D
The maximum shear stresses are not equal and the twist angles are not equal
正确答案： A
19.单选题 (2分)
For symmetric structures and antisymmetric loads. Which of the following conclusions is correct? ()
A
The axial force, shear force and bending moment on the symmetric section must be equal to 0.
B
The axial force and bending moment on the symmetric section must be equal to 0, and the shear force may not be equal to 0.
C
The axial force and bending moment on the symmetric section may not be equal to 0, the shear force must be equal to 0.
D
The axial force, shear force and bending moment on the symmetric section may not be equal to 0.
正确答案： D
20.单选题 (2分)
The figure shows that the force is F=3kN on beam AB. The side of the square section are 100 mm. The maximum tensile stress and the maximum compressive stress in the beam are () respectively.
10.jpg
A
6.8MPa, 7.0MPa;
B
5.4MPa,7.0MPa;
C
6.8MPa,8.7MPa;
D
5.4MPa,8.7MPa;
正确答案： A
21.单选题 (2分)
The basic method to study the internal forces of components in material mechanics is() .
A
Superposition method
B
Method of section
C
Force method
D
Energy method
正确答案： B
22.单选题 (2分)
An item with the weight of P is unleashed with initial velocity v=0 above the contact surface of the component. The maximal impact force of the component caused by the weight is ()
A
2P
B
3P
C
P
D
4P
正确答案： A
23.单选题 (2分)
The figure shows that a rectangular section tensile bar with a h/2 gap in the middle. The maximal stress in the sections with gap is ( ) that in other sections without gap.
1.jpg
A
twice
B
4 times
C
8 times
D
16 times
正确答案： A
24.单选题 (2分)
As shown in the figure, for the statically indeterminate beam. Release the redundant constraint to get the primary structure. Which of the following conclusions is incorrect? ()3.jpg
A
Release the vertical constraint at B
B
Release the horizontal constraint at A
C
Release the vertical constraint at A
D
Release the rotation constraint at A
正确答案： B
25.单选题 (2分)
The member undergoes an infinite number of stress cycles without fatigue failure (), which is called the endurance limit of the member.()
A
Stress amplitude
B
Mean stress
C
Maximum stress
D
Minimum stress
正确答案： C
26.多选题 (2分)
The beams with the same section of same materials in fig.() and fig.(), and () is laminated beam, with no friction between layers. Considering strength condition of the normal stress, the maximum load of beam () is()times of that of beam().()
A
6
B
8
C
4
D
2
正确答案： A,B,D (少选不得分)
27.单选题 (2分)
Under the same material conditions, as the flexibility increases, ( )
A
The critical stress of the long column decreases while that of the medium flexibility bar remains unchanged
B
The critical stress of the intermediate column decreases while that of the large flexibility bar remains unchanged
C
The critical stress of the large and the intermediate column are both decreased
D
The critical stress of the large and the intermediate column are both unchanged
正确答案： C
28.单选题 (2分)
On the assumption of uniformity, the _______of a component is assumed to be the same everywhere.()
A
Displacement
B
Stress
C
Strain
D
Modulus of elasticity
正确答案： D
29.单选题 (2分)
The elastic modulus of a material E=200GPa. Poisson's ratio μ=0.30. Then the shear modulus of the material G=()GPa.()
A
52.5
B
57.8
C
65.5
D
76.9
正确答案： D
30.单选题 (2分)
The beams with the same section of same materials in fig.() and fig.(), and () is laminated beam, with no friction between layers. Considering strength condition of the normal stress, the maximum load of beam () is()times of that of beam().
10.jpg
A
6
B
8
C
4
D
2
正确答案： D
31.单选题 (2分)
Impact problems can be solved by energy method. The impact body is regarded as a rigid one. Compared with the actual situation, the calculated result by energy method is ()
A
Impact stress is bigger while impact deformation is smaller
B
Impact stress impact deformation are smaller
C
Impact stress and impact deformation are bigger
D
Impact stress is smaller while impact deformation is bigger
正确答案： C
32.单选题 (2分)
The essence of canonical equation of the force method is ().
A
Equilibrium equation of force
B
Compatibility equation
C
Physical equation
D
Energy conservation equation
正确答案： B
33.单选题 (2分)
The assumption of deformed solids in material mechanics does not include() .
A
Continuity hypothesis
B
Uniformity hypothesis
C
Isotropic hypothesis
D
Plane hypothesis
正确答案： D
34.单选题 (2分)
Among the following conclusions about the critical stress σcr of the compressive column, the correct one is ()
A
Theσcr value of the long column is independent of the material
B
Theσcr value of the intermediate column is independent of the flexibility
C
Theσcr value of the intermediate column is independent of the material
D
Theσcr value of the small flexibility column is independent of the flexibility
正确答案： D
35.单选题 (2分)
In the case of free fall, when the weight of the impacted object is doubled and other conditions remain unchanged, the dynamic stress in the impacted object will ()
A
Less than double increase
B
Doubled
C
Increase 2 times
D
Unchanged
正确答案： A
36.单选题 (2分)
A solid circular shaft and a hollow circular shaft have the same length. They are made of the same material and subjected to the same external torque. The ratio of inner diameter to outer diameter of the hollow shaft is 0.8. When the maximum shear stress of the hollow shaft is equal to that of the solid shaft, what’s the weight ratio (hollow shaft /solid shaft)? ()
A
0.51
B
1.95
C
0.84
D
1.20
正确答案： A
37.单选题 (2分)
The maximum shear stress in the rod in tension and compression is 40MPa, then the maximum normal stress in the rod is equal to
A
40MPa
B
60MPa
C
56.6MPa
D
80MPa
正确答案： D
38.单选题 (2分)
There is a linear elastic bar. Which is subjected to concentrated forces F and 2F on cross sections B and C, which following statement about the strain energy of the bar is correct?()
1.jpg
A
The strain energy of the bar is the maximum when F is added first on section B and then 2F is added on section C later.
B
The strain energy of the bar is the maximum when 2F is added first on section C and then F is added on section B later.
C
The strain energy of the bar is the maximum when F and 2F are added proportionally at the same time.
D
The strain energy of the rod is the same when F and 2F added in different order.
正确答案： D
39.单选题 (2分)
For a beam with a concentrated force, which one of the following is true?()
A
At the point of concentrated force action, the shearing force diagram and bending moment diagram both have abrupt change
B
At the point of concentrated force action, there is abrupt change in shear force diagram and no abrupt change in bending moment diagram
C
At the point of concentrated force action, there is no abrupt change both in shear force diagram and bending moment diagram
D
At the point of concentrated force action, there is no abrupt in the shear force diagram and there is abrupt change in the bending moment diagram
正确答案： B
40.单选题 (2分)
The structure welded by hollow round bar AB and bar CD is subjected to loadings showed below. The outside diameter of AB is D=140mm and the ratio of inside and outside diameters is α= d/D=0.8. When the third strength theory is used to check the strength of bar AB, the equivalent stress σr3 of critical point is equal to ( ).
5.jpg
A
98.5MPa
B
104.6MPa
C
135.0MPa
D
157.3MPa
正确答案： D
41.单选题 (2分)
Using the unit-load method to calculate the displacement of statically indeterminate structures. Which of the following conclusions is correct? ()
A
The unit load can only be added to the corresponding primary structure.
B
The unit load can only be added to the original statically indeterminate structure.
C
The Unit load can be added to the corresponding equivalent system.
D
Unit load can be added to the original statically indeterminate structure or the corresponding primary structure.
正确答案： D
42.单选题 (2分)
When the shear stress exceeds shear proportional limit of the material,which of the following is correct? ()
A
The reciprocal theorem of shear stresses is not valid
B
The reciprocal theorem of shear stresses is right
C
Shear hooke's law still is right
D
Shear deformation is still elastic deformation
正确答案： B
43.单选题 (2分)
The approximate differential equation of the deflection curve of the beam should satisfy which of the following conditions().()
A
The deformation is small
B
The deflection is in a plane
C
Materials obey Hook's law
D
All three conditions above
正确答案： D
44.单选题 (2分)
Hook's law holds within the
A
Elastic limit
B
Proportional limit
C
Strength limit
D
Yield limit
正确答案： B
45.单选题 (2分)
There is a rectangular section beam with h/b=2，If the cross section is changed from (fig. a) to (fig.b), the maximum deflection of the beam is ( ) times of the original.
5.jpg
A
16
B
4
C
2
D
8
正确答案： B
46.单选题 (2分)
For symmetric structures and symmetric loads. Which of the following conclusions is correct? ()
A
The axial force, shear force and bending moment on the symmetric section must be equal to 0.
B
The axial force and bending moment on the symmetric section must be equal to 0, and the shear force may not be equal to 0.
C
The axial force and bending moment on the symmetric section may not be equal to 0, the shear force must be equal to 0.
D
The axial force, shear force and bending moment on the symmetric section may not be equal to 0.
正确答案： C
47.单选题 (2分)
In the tensile experiment of low-carbon steel, the stage where the stress remains basically the same while the strain increases significantly is called
A
Strain hardening
B
Elastic region
C
Necking
D
Yielding
正确答案： D
48.单选题 (2分)
In the following discussions of beams, deflection and angle of rotation,conclusion () is correct.()
A
The deflection of section with zero angle of rotation is the maximum
B
The deflection of the section with the largest angle of rotation is the maximum
C
The angle of rotation of the section with the largest deflection is the maximum
D
The first derivative of the deflection is equal to the angle of rotation
正确答案： D
49.单选题 (2分)
The power of the motor's rotor shaft is 150kW and the speed is 15.4 r/s. What is the magnitude of the torque moment produced by this axis? ()
A
93 kN·m
B
1.55 kN·m
C
68.4 kN·m
D
1.14 KNN·m
正确答案： B
50.单选题 (2分)
Compared with plastic materials, the biggest characteristic of the tensile mechanical properties of brittle materials is
A
The stress-strain relationship strictly follows Hooke's law
B
Small deformation under the same tension
C
Low intensity
D
There is almost no plastic deformation before fracture
正确答案： D
