moocMechanics of Materials_4期末答案(慕课2023完整答案)
moocMechanics of Materials_4期末答案(慕课2023完整答案)
Unit Test of Chapter 1
1、期末The答案答案 ability of a member to resist failure under external load is the _______ of material.
A、Strength
B、慕课Stiffness
C、完整Stability
D、期末Plastic
2、答案答案The慕课 capacity of a member to maintain its original equilibrium state under external load is the .
A、Stiffness
B、完整Strength
C、期末Stability
D、答案答案Toughness
3、慕课The完整 assumption of deformed solids in material mechanics does not include .
A、Continuity hypothesis
B、期末Uniformity hypothesis
C、答案答案Isotropic hypothesis
D、慕课Plane hypothesis
4、The stress perpendicular to the section is called .
A、Total stress
B、Normal stress
C、Shear stress
D、Principal stress
5、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
6、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
7、Before deformation, the distance between two points A and B on the tensile sample is 100mm. After deformation, the increment of the distance between two points is mm, so the average linear strain between two points A and B is .
A、
B、
C、
D、
8、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
9、The figure shows that the triangular thin plate is deformed by external forces. The vertical displacement of the corner at angle B is 0.3mm, but AB and BC remain straight. Given that AC=200mm, the average linear strain along the AB side is mm.
A、
B、
C、
D、
10、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
2. Axial tension compression and shear
Unit Test of Chapter 2
1、The application conditions of the normal stress equation is .
A、Materials is in Hooke's law
B、Load within the elastic range
C、The line of action of the axial force passes through the centroid of the section and is perpendicular to the section
D、All above
2、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、Elastic region
B、Yielding
C、Strain hardening
D、Necking
3、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、80MPa
B、40MPa
C、60MPa
D、56.6MPa
4、In the illustrated truss structure, three steel rods. Under the condition that other conditions remain unchanged, after replacing rod 3 with aluminum rod, the axial force on rod 1 and rod 2 will be .
A、Decreased
B、Constant
C、Increased
D、unconfirmed
5、The force of the rod is shown in the figure. If the cross-sectional areas of the AB and BC sections are 2A and A, and the elastic modulus is E, then the displacement of the section C is .
A、0
B、
C、
D、
6、Hook's law holds within the .
A、Elastic limit
B、Proportional limit
C、Yield limit
D、Strength limit
7、According to the stress-strain diagram shown in the figure, it can be judged that the nominal yield limit σ0.2 of the material is equal to MPa.
A、200
B、260
C、300
D、330
8、Compared with plastic materials, the biggest characteristic of the tensile mechanical properties of brittle materials is .
A、Low intensity
B、Small deformation under the same tension
C、There is almost no plastic deformation before fracture
D、The stress-strain relationship strictly follows Hooke's law
9、The variable cross-section rod is shown in the figure. Given that and , the maximum normal stress in the rod is MPa.
A、80
B、100
C、120
D、150
10、As shown in the figure, the connector is known: load F = 60kN, plate width b = 80mm, plate thickness δ = 10mm, rivet diameter d = 12mm, allowable stress [σ] = 160MPa, allowable shear stress [τ] = 120MPa , allowable extrusion stress [σbs]= 240MPa, the material of the plate and the rivet is the same, the following statement is correct.
A、The strength of the connector is
B、Shear strength of the rivet is not satisfied
C、The bearing strength of the rivet is not satisfied
D、The tensile strength of the plate is not satisfied
3. Torsion
Unit Test of Chapter 3
1、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
2、is the torsional shear stress formula of the shaft. The shaft with cross section is applicable to this formula。
A、rectangular
B、elliptical
C、circular
D、any shaped
3、The outer diameter of the hollow circular axis with equal section is D, and the inner diameter is d=D/2, the ends of the shaft are subjected to a torsion couple. The maximum shear stress on its cross section is equal to .
A、
B、
C、
D、
4、The straight shaft is fixed at one end of the section as shown in the figure, and is subject to the action of a torsion couple. Which of the following is the torque diagram of the shaft? ( )
A、
B、
C、
D、
5、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
6、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
7、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
8、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
9、This is a circular shaft with different sections, knowing: AB=1.5l, BC=l, D=2d. The shear modulus of the material is G. What is the twist angle of section C relative to section A? ( )
A、
B、
C、
D、
10、The transfer power of the equal section shaft with diameter d is shown in the figure, the speed of the shaft n=10r/s. the allowable shear stress of the material [τ]=80MPa, the diameter of the shaft should not be less than ( ).
A、28.6mm
B、32.2mm
C、35.5mm
D、39.3mm
4. Geometric Properties of the Section
Unit Test of Chapter 4
1、Where does the axis must pass through if the moments of areas of section with respect to an axis is zero。（ ）
A、Centroid
B、Centroid of mass
C、Center
D、Any point
2、In a series of parallel axes of the plane figure, about which axis is the smallest moment of inertia for the figure?（ ）
A、Symmetric axes
B、Centroidal axis
C、Horizontal axis
D、Any axis
3、If the moment of inertia about a pair of orthogonal coordinate axes is zero, then the pair of coordinate axes must be（ ）。
A、Centroidal axis
B、Principal axes
C、Centroidal principal axes
D、Symmetric axes
4、Determine the relationship between moments of inertia and first moments of area of the semicircle shown in the figure with respect to the y and z axis.（ ）
A、
B、
C、
D、
5、Which value can be positive, negative, or zero in the geometric properties of the section?（ ）
A、First moments of areas and Moments of inertia
B、Polar moments and Moments of inertia
C、Moments of inertia and Products of inertia
D、First Moments of areas and Products of inertia
6、Try to determine the centroid of the following figure. ( )
A、（10，10）
B、（10.5，15.5）
C、（12.5，17.5）
D、（20，25）
7、Determine the first moment of the shadow area shown in the figure with respect to the z axis. （ ）
A、-10000
B、-15000
C、10000
D、15000
8、The size of the section：H=60mm，h=40mm，B=30mm，b=12mm， Determine the moment of inertia of section with respect to the z axis. （ ）
A、528000
B、508000
C、466000
D、428000
9、The area of section is A, the centroid is C and the moment of inertia of section with respect to the z axis is , then is .
A、
B、
C、
D、
10、The side length of square section is a, y and z axes are the two symmetrical axes of the section, y1 and z1 axes are the two orthogonal axes crossing the centroid. Determine the moment of inertia of section with respect to the y1 and product moment of inertia of section with respect to the y1 and z1.（ ）
A、
B、
C、
D、
5. Internal force in Bending
Unit Test of Chapter 5
1、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
2、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
3、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
4、When the position of the concentrated couple “m” in the load of the beam shown in the figure changes within the range of distributed load, which of the following conclusion is correct?
A、Both shear force diagram and bending moment diagram are changed
B、Shear force diagram is unchanged, bending moment diagram is changed
C、Shear force diagram is changed, bending moment diagram is unchanged
D、Both shear force diagram and bending moment diagram are unchanged
5、For a simple beam with a span of L, if it only bears a concentrated force F. When F moves freely on the beam, the conclusion about the maximum shear force FSmax and the maximum bending moment Mmax will be （ ）.
A、
B、
C、
D、
6、FSmax and Mmax with the maximum absolute value of the overhanging beam shown in the figure are（ ）.
A、
B、
C、
D、
7、The bending moment equation of the beam is ，then the shear force on the cross-section “x=3a” is（ ）.
A、3qa/2
B、5qa/2
C、5qa/3
D、3qa
8、Given the diagram of “FS”(no concentrated couple on the beam), then the bending moment values at “a” and “b” on the diagram of “M” are respectively ( ).
A、2kN·m，-2.5kN·m
B、1kN·m，-1.25kN·m
C、2kN·m，-4kN·m
D、1kN·m，-2.5kN·m
9、The reinforced concrete beam with a length of “L” in the figure is lifted up with steel rope, and the distance between the steel rope binding and the end of beam is “x”. In order to minimize the maximum bending moment values “ ” caused by the self-weight of beam, the value of x is ( ).
A、
B、
C、
D、
10、As shown in the figure, the two simple skew beams bear the vertical distributed loading, but the sliding hinged support A on the right end are in different ways, so the relationship between the internal force diagrams of the two beams is（ ）.
A、The diagram of “M” and “FS” are the same, but the diagram of “FN” is different
B、The diagram of “M” “FS” and “FN” are all the same
C、The diagram of “M” “FS” and “FN” are all different
D、The diagram of “M” and “FS” are different, but the diagram of “FN” is the same
6. Stress in bending
Unit Test of Chapter 6
1、A cantilever beam is shown in the figure, the center of section is at point C, for the cross section of the beam,（ ）
A、The neutral axis is z1, and the maximum tensile stress is at the upper edge.
B、The neutral axis is z1, and the maximum tensile stress is at the lower edge.
C、The neutral axis is z0, and the maximum tensile stress is at the upper edge.
D、The neutral axis is z0, and the maximum tensile stress is at the lower edge.
2、If the tension elastic modulus of the beam with rectangular section is greater than the compression elastic modulus, the neutral axis of the section is ( ) when the beam is in pure bending.
A、Above the z-axis.
B、On the z axis.
C、Under the z-axis
D、Non-existent
3、For the two beams with the same material and cross section, the axial tracesare two concentric circles after deformation, and the maximum bending normal stress in (a) and (b) is σa and σb ,so it can be concluded that（ ）
A、
B、
C、
D、The relationship is unknown.
4、
A、At upper edge of section B
B、At lower edge of section B
C、At upper edge of section C
D、At lower edge of section C
5、
A、180 MPa
B、120 MPa
C、60 MPa
D、30 MPa
6、As shown in the figure, there are four section shapes of A, B, C and D of cast iron beam. Considering strength condition of the normal stress, the section shape of （ ） is more reasonable.
A、Fig. A
B、Fig. B
C、Fig. C
D、Fig. D
7、If the normal stresses at point A and B on the section of a bending beam with rectangular section are σA = 20MPa and σB = 10MPa,then the normal stress at point D in the middle of AB is（ ）
A、15 MPa
B、20 MPa
C、10 MPa
D、30 MPa
8、
A、1/4
B、1/8
C、1/12
D、1/16
9、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
10、The beams with the same section of same materials in fig.(A) and fig.(B), and (B) is laminated beam, with no friction between layers. Considering strength condition of the normal stress, the maximum load of beam (A) is（ ）times of that of beam(B)
A、6
B、8
C、4
D、2
7. Deformation of Beam
Unit Test of Chapter 7
1、The approximate differential equation of the deflection curve of the beam should satisfy which of the following conditions（ ）.
A、The deformation is small
B、Materials obey Hook's law
C、The deflection is in a plane
D、All three conditions above
2、In the following discussions of beams, deflection and angle of rotation，conclusion ( ) is correct.
A、The deflection of the section with the largest angle of rotation is the maximum
B、The angle of rotation of the section with the largest deflection is the maximum
C、The deflection of section with zero angle of rotation is the maximum
D、The first derivative of the deflection is equal to the angle of rotation
3、
A、There is no distributed load
B、The distributed load is a linear function of x
C、There is uniformly distributed load
D、The distributed load is a quadratic function of x
4、When determining the displacement of the beam by the integral method, the boundary condition and the continuity condition are（ ）.
A、
B、
C、
D、
5、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.
A、2
B、4
C、8
D、16
6、
A、
B、
C、
D、
7、The figure shows that the flexural stiffness of the beam EI is the same. If the deflection of free ends of the two beams are equal, then P1/P2 is equal to（ ）.
A、16
B、8
C、4
D、2
8、The cantilever beam shown here is subjected to two equal and opposite couples，for the section B（ ）.
A、The deflection is zero, the angle of rotation is not zero
B、The deflection is not zero, the angle of rotation is zero
C、Deflection and angle of rotation are both not zero
D、Both deflection and angle of rotation are both zero
9、
A、2
B、4
C、6
D、8
10、
A、1：2
B、2：1
C、1：1
D、3：1
8.Stress State Analysis and Strength Theory
Unit Test of Chapter 8
1、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
2、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
3、The area of cross section and material of the 3 columns are different, but their ( ) are the same.
A、Equivalent length
B、Coefficient of equivalent length
C、Flexibility
D、Critical stress
4、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.
5、Among the following conclusions about the critical stress σcr of the compressive column, the correct one is ( ).
A、The σcr value of the long column is independent of the material
B、The σcr value of the intermediate column is independent of the flexibility
C、The σcr value of the intermediate column is independent of the material
D、The σcr value of the small flexibility column is independent of the flexibility
6、The cross-sectional area of each column is the same. Under the same conditions, the stability of the column is the best when the column adopts the cross-sectional shape shown in fig. （ ）.
A、a
B、b
C、c
D、d
7、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.
A、a
B、b
C、c
D、d
8、
A、n=4
B、n=3
C、n=2
D、n=1
9、The material and cross-sectional area of each rod shown in fig.(a) are the same, and the force F acts at the point B. If the structure shown in fig. (a) is changed to the structure shown in fig. (b), only the stability of the compressive column is considered, and the rod is a long column. The two allowable external loads [F1]/[F2] is（ ）.
A、
B、
C、
D、
10、
A、248 kN，284kN
B、284 kN，248kN
C、236 kN，284kN
D、248 kN，505kN
9.Combined Deformation
Unit Test of Chapter 9
1、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.
A、twice
B、4 times
C、8 times
D、16 times
2、The figure shows that a cast iron beam with rectangular section. The critical point of the beam is ( ).
A、At point D
B、At point E
C、At point F
D、At point G
3、The figure shows that a bar with equilateral circular section and section modulus in bending is W. The maximal stress in the bar is ( ).
A、4Fl/W
B、
C、6Fl/W
D、
4、
A、
B、
C、
D、
5、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 ( ).
A、98.5MPa
B、104.6MPa
C、135.0MPa
D、157.3MPa
6、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
7、The figure shows that the rectangular member is subjected to the force F1 and F2 . If the normal stress at point A is zero, the relation between F1 and F2 is ( ).
A、
B、
C、
D、
8、
A、
B、
C、
D、
9、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 ( ).
A、43.2
B、46.9
C、50.5
D、59.7
10、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.
A、6.8MPa， 7.0MPa；
B、5.4MPa， 7.0MPa；
C、6.8MPa， 8.7MPa；
D、5.4MPa，8.7MPa；
10.Stability of Compressive Columns
Unit Test of Chapter 10
1、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
2、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
3、The area of cross section and material of the 3 columns are different, but their ( ) are the same.
A、Equivalent length
B、Coefficient of equivalent length
C、Flexibility
D、Critical stress
4、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
5、Among the following conclusions about the critical stress σcr of the compressive column, the correct one is ( )
A、The σcr value of the long column is independent of the material
B、The σcr value of the intermediate column is independent of the flexibility
C、The σcr value of the intermediate column is independent of the materia
D、The σcr value of the small flexibility column is independent of the flexibility
6、The cross-sectional area of each column is the same. Under the same conditions, the stability of the column is the best when the column adopts the cross-sectional shape shown in fig. （ ）.
A、（a）
B、（b）
C、（c）
D、（d）
7、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.
A、（a）
B、（b）
C、（c）
D、（d）
8、
A、n=4
B、n=3
C、n=2
D、n=1
9、The material and cross-sectional area of each rod shown in fig.(a) are the same, and the force F acts at the point B. If the structure shown in fig. (a) is changed to the structure shown in fig. (b), only the stability of the compressive column is considered, and the rod is a long column. The two permissible external loads [F1]/[F2] is（ ）.
A、
B、
C、
D、
10、
A、248 kN，284kN；
B、248 kN，248kN；
C、284 kN，248kN；
D、284 kN，284kN；
11. Energy Method
Unit Test of Chapter 11
1、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?（ ）
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.
2、The strain energy of the linear elastic material beam is . When a concentrated force F is applied to the beam. If changing the force F to 2F, and other conditions are the same, the beam’s strain energy is ( )
A、
B、
C、
D、
3、
A、
B、
C、
D、
4、There is a cantilever beam. When force F is applied to the beam alone, The rotation angle of section B is θ. If adding the moment of couple M first and then adding force F, during the process of adding force F, the moment of couple M ( )
A、doesn’t do work
B、does negative work, the vaule is Mθ
C、does positive work, the vaule is Mθ
D、does negative work, the vaule is 0.5Mθ
5、In following statements about Castigliano Second Theorem, which one is correct? ( )
A、The Castigliano Second Theorem is not equivalent to unit force method. Castigliano Second Theorem can deal with more kinds of problems than unit force method.
B、The Castigliano Second Theorem can be used not only to calculate the linear displacement of the structure, but also to calculate the section rotation angle.
C、The Castigliano Second Theorem requires that there must be a force applied at the desired displacement.
D、The Castigliano Second Theorem can not deal with problems of given numerical load.
6、
A、
B、
C、
D、
7、Simply supported beam of the linear elastic material is shown in the following figure. A is a sliding hinge support，B is a spring supporting . Assuming the beam and the spring’s strain energy are and , The deflection at C is ( ).
A、
B、
C、
D、
8、
A、Algebraic sum of horizontal displacement and vertical displacement
B、Vector sum of horizontal displacement and vertical displacement
C、Total displacement
D、Linear displacement in the direction of 45 degrees (direction of resultant force)
9、When using Mohr Integral Method to calculate the beam’s displacement, the bending-moment equation caused by load and unit force should be established respectively. The requirement is（ ）
A、The coordinate x should be consistent, while the divided beam segments can be inconsistent .
B、The divided beam segments should be consistent, while the coordinate x can be inconsistent.
C、The coordinate x and the segment of the beam should be both exactly consistent.
D、The coordinate x and the segment of the beam can be inconsistent.
10、There is a linear elastic material beam with variable cross section. the beam’s modulus of elasticity is E. If ignoring shearing, the deflection at the mid-span cross section C is ( )
A、
B、
C、
D、
12.Statically Indeterminate problems
Unit Test of Chapter 12
1、The degree of static indeterminacy of the illustrated structure is ( ).
A、1
B、2
C、3
D、4
2、Release the link in the structure shown in the figure to get a corresponding primary structure. The number of released constraints is ( ).
A、1
B、2
C、3
D、0
3、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? ( )
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.
4、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
5、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.
6、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.
7、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.
8、The spring stiffness coefficient of the spring support at the end B is k. EI of the beam is constant. Release the constraints as the figure shows. The correct canonical equation of the force method is ( ).
A、
B、
C、
D、
9、The bending stiffness of each member in the rigid frame shown in the figure is EI. Only bending deformation is considered. The magnitude of the constraint reaction at the end C is ( ).
A、qa/8
B、qa/4
C、qa/2
D、qa
10、The bending stiffness of each member in the rigid frame shown in the figure is EI. Only bending deformation is considered. The angle of the section B is ( ).
A、
B、
C、
D、
13.Dynamic load
Unit Test of Chapter 13
1、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 is smaller while impact deformation is bigger
C、Impact stress and impact deformation are bigger
D、Impact stress impact deformation are smaller
2、Two rods in the diagram with the same materials and dimensions. The force P acting on rod a. The self-weight of the rods can be neglected; rod b is on a smooth plane and moving with equal acceleration under the action of P. When comparing the magnitude of internal force in any section of the two rods: ( )
A、Equal
B、The internal force of rod a is bigger
C、The internal force of rod b is bigger
D、Unable to judge
3、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、d remains unchanged; enlarge ω
B、ω remains unchanged; enlarge d
C、ω and d remain unchanged; increase size of the section
D、reduce d or ω
4、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、P
B、2P
C、3P
D、4P
5、Weight Q impacts the midpoint of the simply supported beam respectively from the above, below and horizonal direction. Set the speed when the weight contacts the beam as v. The weight of the beam can be neglected. The maximum normal stress of the beam is at ( )
A、Rod a
B、Rod b
C、Rod c
D、Unable to judge
6、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、Unchanged
B、Increase 2 times
C、Doubled
D、Less than double increase
7、As shown in the figure, the material and cross section of the two columns are the same, and the maximum dynamic stress is the same during impact, then the length ratio of the two columns is of the two columns is ( )
A、4
B、3
C、2.5
D、2
8、The three columns in the diagram are impacted by free fall body, compare the maximum dynamic stresses between the three ( )
A、
B、
C、
D、
9、The two beams in the diagram with the same flexural rigidity and stiffness coefficient of the springs is the same. Compare the maximum dynamic stress of the two beams ( )
A、
B、
C、
D、Not sure
10、Diameter of a column is d=300mm and its length is l=6m with rubber pad with diameter of 150 mm and thickness of 40 mm placed on the top. The elasticity modulus of the rubber pad is 8MPa. An object with a weight of P=2kN falls freely from the height h=0.5m from the top of the rubber pad. The elasticity modulus of the column is 10GPa, Please determinate the coefficient of the dynamic load ( )
A、20
B、24
C、42
D、64
14. Alternative Stress
Unit Test of Chapter 14
1、The average stress σm and stress amplitude σa of the alternating stress in the figure are respectively ( ).
A、σm = 40MPa，σa = -120 MPa
B、σm = -40MPa，σa = -40 MPa
C、σm = 0MPa，σa = 120 MPa
D、σm = -40MPa，σa = 80 MPa
2、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
3、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
4、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
5、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
6、Which of the following measures will reduce the endurance limit of components ( ).
A、Reduce stress concentration
B、Reduce surface roughness of components
C、Improve surface strength of components
D、Increase the section size of the member
学习通Mechanics of Materials_4
《Mechanics of Materials_4》是一门重要的工程力学课程，它是机械、航空、土木等工程专业的基础课程之一。这门课程主要讲解材料的力学性质，如弹性模量、屈服点、断裂强度等，以及在不同应力状态下的变形和破坏机制。在实际工程应用中，这些知识是非常重要的。
课程内容
该课程主要分为以下几个部分：
- 应力和应变
- 轴向载荷下的应变和应力
- 弯曲和剪切
- 挤压、拉伸和扭转
- 复合应力和复合变形
- 梁的变形
- 斜截面梁的变形
- 应力和变形的能量原理
- 破坏理论
这些内容非常深入，需要学生认真学习和掌握。
课程教学
《Mechanics of Materials_4》的教学方式非常多样，包括讲授、实验、案例分析等。通过多种教学方式的组合，学生可以更好地理解和掌握课程内容。
在讲授环节，教师会对每个知识点进行详细的解释和讲解，让学生能够理解知识的本质和应用场景。
在实验环节，学生可以通过实际操作，更好地了解不同力学性质的实际表现。通过实验数据的分析和整理，学生可以更深入地理解课程内容。
在案例分析环节，教师会选取一些实际案例，通过解析案例中的力学问题，让学生更好地了解力学知识在实际工程中的应用。
课程评估
《Mechanics of Materials_4》的考核方式通常是课程作业和期末考试。课程作业通常包括理论和实验两部分，理论部分要求学生用自己的语言解释所学知识点；实验部分要求学生进行实验操作并整理实验数据。期末考试主要考察学生对整个课程的掌握程度。
总结
《Mechanics of Materials_4》是一门非常重要的工程力学课程，它是机械、航空、土木等工程专业的基础课程之一。通过本课程的学习，学生可以更好地理解材料的力学性质，以及在不同应力状态下的变形和破坏机制。同时，该课程的多样化教学方式，也能够帮助学生更好地掌握课程内容。
自媒体一般通过哪些途径获取广告合作（ ）。
A.胃和部分肠管被网膜包裹。
B.下列选项中不属于社会理想的是
C.同步发电机获得励磁电流的方式有
D.在测量表达式2∧()中，在∧前添加\即可显示为√2
我国目前已经进入小康社会，到2020年我们就可以实现共同富裕目标。（ ）
A.7．在下列英文字母中（）不用于表示Bmnay的等级。
B.常见的冷凝-蒸发器的结构形式有（ ）。
C.亲代与子代之间的亲缘关系指数是()
D.“莼鲈之思”这个典故出自于《世说新语》，故事的主人公是谁
西餐宴会男女穿插就座（）
A.如果要为演示文稿快捷地设定整体、专业的外观，应该应用 。
B.在短跑技术教学的开始阶段要强调自然放松、有弹性的大步幅跑的技术。
C.《秦王破阵乐》共有七首乐曲，《秦王破阵乐》是其中的第二首。
D.对于实际气体的压缩因子，以下错误的说法是（ ）。
把不同采样点,同时采集的各个瞬时水样混合后所得到的样品称为()。
A.自灌式泵房的水泵吸水管上应设有（ ），以满足水泵检修的需要。
B.下列关于肝硬化分类的叙述,错误的是
C.计算机中，负责指挥计算机各部分自动协调一致地进行工作的部件是（）
D.陆运战争险承保责任范围仅限于（ ）
图示两个结构的计算自由度和自由度是相同的。 （ ）
A.被称为“抓拍之父”的是：
B.（tt2-2）理想流体是可压缩但没有黏滞性的流体。
C.正义原则高于宪法，宪法高于法律。
D.心理距离无所谓，关系如“路人”。这属于心理距离的哪一级：
无脑儿是一种神经发育相关疾病，这与（）相关。
A.要求企业对于已经发生的交易
B.客服只能招聘女性员工。( )
C.能影响短波限位置的因素是( )
D.交流接触器的（）用于通断电流较大的主电路
A SNARE is（ ）
A.目前有超过多少种疾病和伤害与饮酒有关
B.毛村中保存的《遵判堂断税山税地碑记》立于清嘉庆十五年，也就是公元（ ）年。
C.总结手动控制策略，得出一组由模糊条件语句构成的控制规则，据此可建立（ ）
D.下面关于电影《苏州河》表达不正确的一项是：（）
引起心交感神经的活动减弱的情况是：
A.韩国的文字“训民正音”是哪一年创制出来的
B.构件由突加载荷所引起的动应力，是由相应的静载荷所引起的应力的两倍。
C.第谷富甲天下,但是像天下大多数富人那样,他不知道如何恰当使用这些财富。( )
D.当实际电源的参数不变，将负载增大，则线路中的电流（ ）
如果厂商的边际收益大于边际成本，则应该（ ）
A.将浓硫酸与少量KI固体混合，还原产物主要是( )。
B.公司简介应该包括的部分有()。
C.若在一区间上，曲线总在它每一点的切线上方，则曲线在这区间是凹的。
D.一般来说，材料的孔隙率与下列性能没有关系的是（）。
医院膳食大体分为（）（2分）
A.青年是理想形成的重要时期,也是立志的关键阶段。
B.CCA是实现木材防虫的有效环保防虫剂
C.性取向，也称性倾向，是一个人在情感、浪漫与性上对男性或女性有何种型态的耐久吸引
D.实际电气设备大多为感性设备，功率因数往往较低。
温床除利用太阳辐射热外，还需增加人工热以补充太阳辐射热的不足。
A.随着人工智能的不断发展，教育过程中的教师将被取代。
B.ae6a5f0659944ef690dd2e8764b6d582.png
C.设f(x)g(x)是恒大于零的可导函数
D.DNA损伤有多种类型，从化学本质看，突变的DNA分子改变可分为：（ ）。
以下有关类的继承的叙述中，正确的是：
A.下面哪些属于人力资源规划的作用
B.温度对流体粘性的影响是，随温度的升高，气体的粘度增大。
C.圆锥的截交线含有三角形。
D.增大氧流量正确的调节方法
下列不属于脊神经纤维成分的是哪种
A.一般情况下，商务场合中的男子不宜佩戴的饰物是（ ）。
B.心肌没有横纹，不属于横纹肌
C.以下哪个算法不属于对称密钥算法。（）
D.] 葡萄酒的年份是指 _____________ 。
栅格数据表示地物的精度取决于（）。
A.招募、甄选和录用工作的基础是（）。
B.常见的组团绿地形式有 。
C.LM393 是双电压比较器集成电路。
D.一个质量为0.5kg的小球，从5m高处自由下落
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