the ability of a member to resist failure under external load is the _______ of material.
the capacity of a member to maintain its original equilibrium state under external load is the .
the assumption of deformed solids in material mechanics does not include .
the stress perpendicular to the section is called .
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 .
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 .
the basic method to study the internal forces of components in material mechanics is .
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.
on the assumption of uniformity, the of a component is assumed to be the same everywhere.
the application conditions of the normal stress equation is .
in the tensile experiment of low-carbon steel, the stage where the stress remains basically the same while the strain increases significantly is called .
the maximum shear stress in the rod in tension and compression is 40mpa, then the maximum normal stress in the rod is equal to .
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 .
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 .
hook's law holds within the .
compared with plastic materials, the biggest characteristic of the tensile mechanical properties of brittle materials is .
the variable cross-section rod is shown in the figure. given that and , the maximum normal stress in the rod is mpa.
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? ( )
is the torsional shear stress formula of the shaft. the shaft with cross section is applicable to this formula。
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 .
the elastic modulus of a material e=200gpa. poisson's ratio μ=0.30. then the shear modulus of the material g= gpa.
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? ( )
which value can be positive, negative, or zero in the geometric properties of the section?（ ）
try to determine the centroid of the following figure. ( )
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. （ ）
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 .
for a simple beam under distributed load, at the middle of the span, which one of the following is true?
the bending moment equation of the beam is ，then the shear force on the cross-section “x=3a” is（ ）.
a cantilever beam is shown in the figure, the center of section is at point c, for the cross section of the beam,（ ）
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（ ）
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)
if the coefficient of equivalent length of the long column is doubled, the critical pressure of the column will be ( ).
the area of cross section and material of the 3 columns are different, but their ( ) are the same.
under the same material conditions, as the flexibility increases, ( ).
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.
if the coefficient of equivalent length of the long column is doubled, the critical pressure of the column will be ( ).
the area of cross section and material of the 3 columns are different, but their ( ) are the same.
under the same material conditions, as the flexibility increases, ( )
in following statements about castigliano second theorem, which one is correct? ( )
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 ( ).
the essence of canonical equation of the force method is ( ).
for symmetric structures and symmetric loads. which of the following conclusions is correct? ( )
for symmetric structures and antisymmetric loads. which of the following conclusions is correct? ( )