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Bending of plates, or plate bending, refers to the
deflection Deflection or deflexion may refer to: Board games * Deflection (chess), a tactic that forces an opposing chess piece to leave a square * Khet (game), formerly ''Deflexion'', an Egyptian-themed chess-like game using lasers Mechanics * Deflection ...
of a plate perpendicular to the plane of the plate under the action of external
force In physics, a force is an influence that can cause an Physical object, object to change its velocity unless counterbalanced by other forces. In mechanics, force makes ideas like 'pushing' or 'pulling' mathematically precise. Because the Magnitu ...
s and moments. The amount of deflection can be determined by solving the differential equations of an appropriate plate theory. The stresses in the plate can be calculated from these deflections. Once the stresses are known, failure theories can be used to determine whether a plate will fail under a given load.


Bending of Kirchhoff-Love plates


Definitions

For a thin rectangular plate of thickness H,
Young's modulus Young's modulus (or the Young modulus) is a mechanical property of solid materials that measures the tensile or compressive stiffness when the force is applied lengthwise. It is the modulus of elasticity for tension or axial compression. Youn ...
E, and
Poisson's ratio In materials science and solid mechanics, Poisson's ratio (symbol: ( nu)) is a measure of the Poisson effect, the deformation (expansion or contraction) of a material in directions perpendicular to the specific direction of loading. The value ...
\nu, we can define parameters in terms of the plate deflection, w. The
flexural rigidity Flexural rigidity is defined as the force couple required to bend a fixed non- rigid structure by one unit of curvature, or as the resistance offered by a structure while undergoing bending. Flexural rigidity of a beam Although the moment M(x) ...
is given by : D = \frac


Moments

The
bending moment In solid mechanics, a bending moment is the Reaction (physics), reaction induced in a structural element when an external force or Moment of force, moment is applied to the element, causing the element to bending, bend. The most common or simplest ...
s per unit length are given by : M_ = -D \left( \frac + \nu \frac \right) : M_ = -D \left( \nu \frac + \frac \right) The twisting moment per unit length is given by : M_ = -D \left( 1 - \nu \right) \frac


Forces

The
shear force In solid mechanics, shearing forces are unaligned forces acting on one part of a Rigid body, body in a specific direction, and another part of the body in the opposite direction. When the forces are Collinearity, collinear (aligned with each ot ...
s per unit length are given by : Q_ = -D \frac \left( \frac + \frac \right) : Q_ = -D \frac \left( \frac + \frac \right)


Stresses

The bending stresses are given by : \sigma_ = -\frac \left( \frac + \nu \frac \right) : \sigma_ = -\frac \left( \nu \frac + \frac \right) The
shear stress Shear stress (often denoted by , Greek alphabet, Greek: tau) is the component of stress (physics), stress coplanar with a material cross section. It arises from the shear force, the component of force vector parallel to the material cross secti ...
is given by : \tau_ = -\frac \left(1-\nu\right) \frac


Strains

The bending strains for small-deflection theory are given by : \epsilon_ = \frac = -z\frac : \epsilon_ = \frac = -z\frac The
shear strain In mechanics, strain is defined as relative deformation, compared to a position configuration. Different equivalent choices may be made for the expression of a strain field depending on whether it is defined with respect to the initial or the ...
for small-deflection theory is given by : \gamma_ = \frac + \frac = -2z\frac For large-deflection plate theory, we consider the inclusion of membrane strains : \epsilon_ = \frac + \frac\left(\frac\right)^2 : \epsilon_ = \frac + \frac\left(\frac\right)^2 : \gamma_ = \frac + \frac + \frac \frac


Deflections

The deflections are given by : u = -z\frac : v = -z\frac


Derivation

In the
Kirchhoff–Love plate theory The Kirchhoff–Love theory of plates is a two-dimensional mathematical model that is used to determine the stresses and deformations in thin plates subjected to forces and moments. This theory is an extension of Euler-Bernoulli beam theory ...
for plates the governing equations areReddy, J. N., 2007, Theory and analysis of elastic plates and shells, CRC Press, Taylor and Francis. : N_ = 0 and : M_ - q = 0 In expanded form, : \cfrac + \cfrac = 0 ~;~~ \cfrac + \cfrac = 0 and : \cfrac + 2\cfrac + \cfrac = q where q(x) is an applied transverse load per unit area, the thickness of the plate is H=2h, the stresses are \sigma_, and : N_ := \int_^h \sigma_~dx_3 ~;~~ M_ := \int_^h x_3~\sigma_~dx_3~. The quantity N has units of
force In physics, a force is an influence that can cause an Physical object, object to change its velocity unless counterbalanced by other forces. In mechanics, force makes ideas like 'pushing' or 'pulling' mathematically precise. Because the Magnitu ...
per unit length. The quantity M has units of moment per unit length. For
isotropic In physics and geometry, isotropy () is uniformity in all orientations. Precise definitions depend on the subject area. Exceptions, or inequalities, are frequently indicated by the prefix ' or ', hence '' anisotropy''. ''Anisotropy'' is also ...
,
homogeneous Homogeneity and heterogeneity are concepts relating to the uniformity of a substance, process or image. A homogeneous feature is uniform in composition or character (i.e., color, shape, size, weight, height, distribution, texture, language, i ...
, plates with
Young's modulus Young's modulus (or the Young modulus) is a mechanical property of solid materials that measures the tensile or compressive stiffness when the force is applied lengthwise. It is the modulus of elasticity for tension or axial compression. Youn ...
E and
Poisson's ratio In materials science and solid mechanics, Poisson's ratio (symbol: ( nu)) is a measure of the Poisson effect, the deformation (expansion or contraction) of a material in directions perpendicular to the specific direction of loading. The value ...
\nu these equations reduce toTimoshenko, S. and Woinowsky-Krieger, S., (1959), Theory of plates and shells, McGraw-Hill New York. : \nabla^2\nabla^2 w = -\cfrac ~;~~ D := \cfrac = \cfrac where w(x_1,x_2) is the deflection of the mid-surface of the plate.


Small deflection of thin rectangular plates

This is governed by the
Germain Germain may refer to: *Germain (name), including a list of people with the name *Germain Arena, the former name of an arena in Estero, Florida *Germain Racing, a NASCAR racing team *Germain Amphitheater, a concert venue in Columbus, Ohio *Paris Sa ...
-
Lagrange Joseph-Louis Lagrange (born Giuseppe Luigi LagrangiaFöppl– von Kármán plate equations : \cfrac + 2\cfrac + \cfrac = E\left left(\cfrac\right)^2 - \cfrac \cfrac\right : \cfrac + 2\cfrac + \cfrac = \cfrac + \cfrac\left( \cfrac\cfrac + \cfrac\cfrac - 2\cfrac\cfrac \right) where F is the stress function.


Circular Kirchhoff-Love plates

The bending of circular plates can be examined by solving the governing equation with appropriate boundary conditions. These solutions were first found by Poisson in 1829. Cylindrical coordinates are convenient for such problems. Here z is the distance of a point from the midplane of the plate. The governing equation in coordinate-free form is : \nabla^2 \nabla^2 w = -\frac \,. In cylindrical coordinates (r, \theta, z), : \nabla^2 w \equiv \frac\frac\left(r \frac\right) + \frac\frac + \frac \,. For symmetrically loaded circular plates, w = w(r), and we have : \nabla^2 w \equiv \frac\cfrac\left(r \cfrac\right) \,. Therefore, the governing equation is : \frac\cfrac\left \cfrac\left\\right= -\frac\,. If q and D are constant, direct integration of the governing equation gives us
: w(r) = -\frac + C_1\ln r + \cfrac + \cfrac(2\ln r - 1) + C_4
where C_i are constants. The slope of the deflection surface is : \phi(r) = \cfrac = -\frac + \frac + C_2 r + C_3 r \ln r \,. For a circular plate, the requirement that the deflection and the slope of the deflection are finite at r = 0 implies that C_1 = 0. However, C_3 need not equal 0, as the limit of r \ln r\, exists as you approach r = 0 from the right.


Clamped edges

For a circular plate with clamped edges, we have w(a) = 0 and \phi(a) = 0 at the edge of the plate (radius a). Using these boundary conditions we get
: w(r) = -\frac (a^2 -r^2)^2 \quad \text \quad \phi(r) = \frac(a^2-r^2) \,.
The in-plane displacements in the plate are : u_r(r) = -z\phi(r) \quad \text \quad u_\theta(r) = 0 \,. The in-plane strains in the plate are : \varepsilon_ = \cfrac = -\frac(a^2-3r^2) ~,~~ \varepsilon_ = \frac = -\frac(a^2-r^2) ~,~~ \varepsilon_ = 0 \,. The in-plane stresses in the plate are : \sigma_ = \frac\left varepsilon_ + \nu\varepsilon_\right~;~~ \sigma_ = \frac\left varepsilon_ + \nu\varepsilon_\right~;~~ \sigma_ = 0 \,. For a plate of thickness 2h, the bending stiffness is D = 2Eh^3/ (1-\nu^2)/math> and we have
: \begin \sigma_ &= -\frac\left 1+\nu)a^2-(3+\nu)r^2\right\\ \sigma_ &= -\frac\left 1+\nu)a^2-(1+3\nu)r^2\right\ \sigma_ &= 0 \,. \end
The moment resultants (bending moments) are : M_ = -\frac\left 1+\nu)a^2-(3+\nu)r^2\right~;~~ M_ = -\frac\left 1+\nu)a^2-(1+3\nu)r^2\right~;~~ M_ = 0 \,. The maximum radial stress is at z = h and r = a: : \left.\sigma_\_ = \frac = \frac where H := 2h. The bending moments at the boundary and the center of the plate are : \left.M_\_ = \frac ~,~~ \left.M_\_ = \frac ~,~~ \left.M_\_ = \left.M_\_ = -\frac \,.


Rectangular Kirchhoff-Love plates

For rectangular plates, Navier in 1820 introduced a simple method for finding the displacement and stress when a plate is simply supported. The idea was to express the applied load in terms of Fourier components, find the solution for a sinusoidal load (a single Fourier component), and then superimpose the Fourier components to get the solution for an arbitrary load.


Sinusoidal load

Let us assume that the load is of the form : q(x,y) = q_0 \sin\frac\sin\frac \,. Here q_0 is the amplitude, a is the width of the plate in the x-direction, and b is the width of the plate in the y-direction. Since the plate is simply supported, the displacement w(x,y) along the edges of the plate is zero, the bending moment M_ is zero at x=0 and x=a, and M_ is zero at y=0 and y=b. If we apply these boundary conditions and solve the plate equation, we get the solution : w(x,y) = \frac\,\left(\frac+\frac\right)^\,\sin\frac\sin\frac \,. Where D is the flexural rigidity : D=\frac Analogous to flexural stiffness EI. We can calculate the stresses and strains in the plate once we know the displacement. For a more general load of the form : q(x,y) = q_0 \sin\frac\sin\frac where m and n are integers, we get the solution
: \text \qquad w(x,y) = \frac\,\left(\frac+\frac\right)^\,\sin\frac\sin\frac \,.


Navier solution


Double trigonometric series equation

We define a general load q(x,y) of the following form : q(x,y) = \sum_^ \sum_^\infty a_\sin\frac\sin\frac where a_ is a Fourier coefficient given by : a_ = \frac\int_0^b \int_0^a q(x,y)\sin\frac\sin\frac\,\textx\texty . The classical rectangular plate equation for small deflections thus becomes: : \cfrac + 2\cfrac + \cfrac = \cfrac \sum_^ \sum_^\infty a_\sin\frac\sin\frac


Simply-supported plate with general load

We assume a solution w(x,y) of the following form : w(x,y) = \sum_^ \sum_^\infty w_\sin\frac\sin\frac The partial differentials of this function are given by : \cfrac = \sum_^ \sum_^\infty \left(\frac\right)^4 w_\sin\frac\sin\frac : \cfrac = \sum_^ \sum_^\infty \left(\frac\right)^2 \left(\frac\right)^2 w_\sin\frac\sin\frac : \cfrac = \sum_^ \sum_^\infty \left(\frac\right)^4 w_\sin\frac\sin\frac Substituting these expressions in the plate equation, we have : \sum_^ \sum_^\infty \left( \left(\frac\right)^2 + \left(\frac\right)^2 \right)^2 w_\sin\frac\sin\frac = \sum_^ \sum_^\infty \cfrac \sin\frac\sin\frac Equating the two expressions, we have : \left( \left(\frac\right)^2 + \left(\frac\right)^2 \right)^2 w_ = \cfrac which can be rearranged to give : w_ = \frac\frac The deflection of a simply-supported plate (of corner-origin) with general load is given by
: w(x,y) = \frac \sum_^\infty \sum_^\infty \frac \sin\frac\sin\frac


Simply-supported plate with uniformly-distributed load

: For a uniformly-distributed load, we have : q(x,y) = q_0 The corresponding Fourier coefficient is thus given by : a_ = \frac \int_0^a \int_0^b q_0\sin\frac\sin\frac\,\textx\texty . Evaluating the double integral, we have : a_ = \frac(1 - \cos m\pi)(1 - \cos n\pi) , or alternatively in a
piecewise In mathematics, a piecewise function (also called a piecewise-defined function, a hybrid function, or a function defined by cases) is a function whose domain is partitioned into several intervals ("subdomains") on which the function may be ...
format, we have : a_ = \begin \cfrac & m~\text~n~\text \\ 0 & m~\text~n~\text \end The deflection of a simply-supported plate (of corner-origin) with uniformly-distributed load is given by
: w(x,y) = \frac \sum_^\infty \sum_^\infty \frac \sin\frac\sin\frac
The bending moments per unit length in the plate are given by
: M_ = \frac \sum_^\infty \sum_^\infty \frac \sin\frac\sin\frac : M_ = \frac \sum_^\infty \sum_^\infty \frac \sin\frac\sin\frac


Lévy solution

Another approach was proposed by LévyLévy, M., 1899, Comptes rendues, vol. 129, pp. 535-539 in 1899. In this case we start with an assumed form of the displacement and try to fit the parameters so that the governing equation and the boundary conditions are satisfied. The goal is to find Y_m(y) such that it satisfies the boundary conditions at y = 0 and y = b and, of course, the governing equation \nabla^2 \nabla^2 w = q/D. Let us assume that : w(x,y) = \sum_^\infty Y_m(y) \sin \frac \,. For a plate that is simply-supported along x=0 and x=a, the boundary conditions are w=0 and M_=0. Note that there is no variation in displacement along these edges meaning that \partial w/\partial y = 0 and \partial^2 w/\partial y^2 = 0, thus reducing the moment
boundary condition In the study of differential equations, a boundary-value problem is a differential equation subjected to constraints called boundary conditions. A solution to a boundary value problem is a solution to the differential equation which also satis ...
to an equivalent expression \partial^2 w/\partial x^2 = 0.


Moments along edges

Consider the case of pure moment loading. In that case q = 0 and w(x,y) has to satisfy \nabla^2 \nabla^2 w = 0. Since we are working in rectangular Cartesian coordinates, the governing equation can be expanded as : \frac + 2 \frac + \frac = 0 \,. Plugging the expression for w(x,y) in the governing equation gives us : \sum_^\infty \left left(\frac\right)^4 Y_m \sin\frac - 2\left(\frac\right)^2 \cfrac \sin\frac + \frac \sin\frac\right= 0 or : \frac - 2 \frac \cfrac + \frac Y_m = 0 \,. This is an
ordinary differential equation In mathematics, an ordinary differential equation (ODE) is a differential equation (DE) dependent on only a single independent variable (mathematics), variable. As with any other DE, its unknown(s) consists of one (or more) Function (mathematic ...
which has the general solution : Y_m = A_m \cosh\frac + B_m\frac \cosh\frac + C_m \sinh\frac + D_m\frac \sinh\frac where A_m, B_m, C_m, D_m are constants that can be determined from the boundary conditions. Therefore, the displacement solution has the form
: w(x,y) = \sum_^\infty \left \left(A_m + B_m\frac\right) \cosh\frac + \left(C_m + D_m\frac\right) \sinh\frac \right\sin \frac \,.
Let us choose the coordinate system such that the boundaries of the plate are at x = 0 and x = a (same as before) and at y = \pm b/2 (and not y=0 and y=b). Then the moment boundary conditions at the y = \pm b/2 boundaries are : w = 0 \,, -D\frac\Bigr, _ = f_1(x) \,, -D\frac\Bigr, _ = f_2(x) where f_1(x), f_2(x) are known functions. The solution can be found by applying these boundary conditions. We can show that for the ''symmetrical'' case where : M_\Bigr, _ = M_\Bigr, _ and : f_1(x) = f_2(x) = \sum_^\infty E_m\sin\frac we have
: w(x,y) = \frac\sum_^\infty \frac\, \sin\frac\, \left(\alpha_m \tanh\alpha_m \cosh\frac - \frac\sinh\frac\right)
where : \alpha_m = \frac \,. Similarly, for the ''antisymmetrical'' case where : M_\Bigr, _ = -M_\Bigr, _ we have
: w(x,y) = \frac\sum_^\infty \frac\, \sin\frac\, \left(\alpha_m \coth\alpha_m \sinh\frac - \frac\cosh\frac\right) \,.
We can superpose the symmetric and antisymmetric solutions to get more general solutions.


Simply-supported plate with uniformly-distributed load

For a uniformly-distributed load, we have : q(x,y) = q_0 The deflection of a simply-supported plate with centre \left(\frac, 0\right) with uniformly-distributed load is given by
: \begin &w(x,y) = \frac \sum_^\infty \left( A_m\cosh\frac + B_m\frac\sinh\frac + G_m\right) \sin\frac\\\\ &\begin \text\quad &A_m = -\frac\\ &B_m = \frac\\ &G_m = \frac\\\\ \text\quad &\alpha _m = \frac \end \end
The bending moments per unit length in the plate are given by
: M_x = -q_0\pi^2 a^2\sum_^\infty m^2\left( \left(\left(\nu -1\right)A_m + 2\nu B_m\right)\cosh\frac + \left(\nu -1\right)B_m\frac\sinh\frac - G_m\right) \sin\frac : M_y = -q_0\pi^2 a^2\sum_^\infty m^2\left( \left(\left(1-\nu\right)A_m + 2B_m\right)\cosh\frac + \left(1-\nu\right)B_m\frac\sinh\frac - \nu G_m\right) \sin\frac


Uniform and symmetric moment load

For the special case where the loading is symmetric and the moment is uniform, we have at y=\pm b/2, : M_ = f_1(x) = \frac\sum_^\infty \frac\,\sin\frac \,. : The resulting displacement is
: \begin & w(x,y) = \frac\sum_^\infty \frac\sin\frac \times\\ & ~~ \left \alpha_m\,\tanh\alpha_m\cosh\frac -\frac \sinh\frac\right \end
where : \alpha_m = \frac \,. The bending moments and shear forces corresponding to the displacement w are : \begin M_ & = -D\left(\frac+\nu\,\frac\right) \\ & = \frac\sum_^\infty\frac\,\times \\ & ~ \sin\frac \,\times \\ & ~ \left -\frac\sinh\frac + \right. \\ & \qquad \qquad \qquad \qquad \left. \left\\cosh\frac \right\\ M_ & = (1-\nu)D\frac \\ & = -\frac\sum_^\infty\frac\,\times \\ & ~ \cos\frac \, \times \\ & ~ \left frac\cosh\frac + \right. \\ & \qquad \qquad \qquad \qquad \left. (1-\alpha_m\tanh\alpha_m)\sinh\frac\right\\ Q_ & = \frac-\frac \\ & = \frac\sum_^\infty \frac\,\times \\ & ~ \cos\frac\cosh\frac\,. \end The stresses are : \sigma_ = \frac\,M_ \quad \text \quad \sigma_ = \frac\,Q_\left(1 - \frac\right)\,.


Cylindrical plate bending

Cylindrical bending occurs when a rectangular plate that has dimensions a \times b \times h, where a \ll b and the thickness h is small, is subjected to a uniform distributed load perpendicular to the plane of the plate. Such a plate takes the shape of the surface of a cylinder.


Simply supported plate with axially fixed ends

For a simply supported plate under cylindrical bending with edges that are free to rotate but have a fixed x_1. Cylindrical bending solutions can be found using the Navier and Levy techniques.


Bending of thick Mindlin plates

For thick plates, we have to consider the effect of through-the-thickness shears on the orientation of the normal to the mid-surface after deformation. Raymond D. Mindlin's theory provides one approach for find the deformation and stresses in such plates. Solutions to Mindlin's theory can be derived from the equivalent Kirchhoff-Love solutions using canonical relations.Lim, G. T. and Reddy, J. N., 2003, ''On canonical bending relationships for plates'', International Journal of Solids and Structures, vol. 40, pp. 3039-3067.


Governing equations

The canonical governing equation for isotropic thick plates can be expressed as : \begin & \nabla^2 \left(\mathcal - \frac\,q\right) = -q \\ & \kappa G h\left(\nabla^2 w + \frac\right) = -\left(1 - \cfrac\right)q \\ & \nabla^2 \left(\frac - \frac\right) = c^2\left(\frac - \frac\right) \end where q is the applied transverse load, G is the
shear modulus In materials science, shear modulus or modulus of rigidity, denoted by ''G'', or sometimes ''S'' or ''μ'', is a measure of the Elasticity (physics), elastic shear stiffness of a material and is defined as the ratio of shear stress to the shear s ...
, D = Eh^3/ 2(1-\nu^2)/math> is the bending rigidity, h is the plate thickness, c^2 = 2\kappa G h/ (1-\nu)/math>, \kappa is the shear correction factor, E is the Young's modulus, \nu is the Poisson's ratio, and : \mathcal = D\left mathcal\left(\frac + \frac\right) - (1-\mathcal)\nabla^2 w\right+ \frac\mathcal \,. In Mindlin's theory, w is the transverse displacement of the mid-surface of the plate and the quantities \varphi_1 and \varphi_2 are the rotations of the mid-surface normal about the x_2 and x_1-axes, respectively. The canonical parameters for this theory are \mathcal = 1 and \mathcal = 0. The shear correction factor \kappa usually has the value 5/6. The solutions to the governing equations can be found if one knows the corresponding Kirchhoff-Love solutions by using the relations : \begin w & = w^K + \frac\left(1 - \frac\right) - \Phi + \Psi \\ \varphi_1 & = - \frac - \frac\left(1 - \frac - \frac\right)Q_1^K + \frac\left(\frac\nabla^2 \Phi + \Phi - \Psi\right) + \frac\frac \\ \varphi_2 & = - \frac - \frac\left(1 - \frac - \frac\right)Q_2^K + \frac\left(\frac\nabla^2 \Phi + \Phi - \Psi\right) + \frac\frac \end where w^K is the displacement predicted for a Kirchhoff-Love plate, \Phi is a biharmonic function such that \nabla^2 \nabla^2 \Phi = 0, \Psi is a function that satisfies the Laplace equation, \nabla^2 \Psi = 0, and : \begin \mathcal & = \mathcal^K + \frac\,q + D \nabla^2 \Phi ~;~~ \mathcal^K := -D\nabla^2 w^K \\ Q_1^K & = -D\frac\left(\nabla^2 w^K\right) ~,~~ Q_2^K = -D\frac\left(\nabla^2 w^K\right) \\ \Omega & = \frac - \frac ~,~~ \nabla^2 \Omega = c^2\Omega \,. \end


Simply supported rectangular plates

For simply supported plates, the ''Marcus moment'' sum vanishes, i.e., : \mathcal = \frac(M_+M_) = D\left(\frac+\frac\right) = 0 \,. Which is almost Laplace`s equation for w ef 6 In that case the functions \Phi, \Psi, \Omega vanish, and the Mindlin solution is related to the corresponding Kirchhoff solution by : w = w^K + \frac \,.


Bending of Reissner-Stein cantilever plates

Reissner-Stein theory for cantilever platesE. Reissner and M. Stein. Torsion and transverse bending of cantilever plates. Technical Note 2369, National Advisory Committee for Aeronautics,Washington, 1951. leads to the following coupled ordinary differential equations for a cantilever plate with concentrated end load q_x(y) at x=a. : \begin & bD \frac = 0 \\ & \frac\,\frac - 2bD(1-\nu)\cfrac = 0 \end and the boundary conditions at x=a are : \begin & bD\cfrac + q_ = 0 \quad,\quad \frac\cfrac -2bD(1-\nu)\cfrac + q_ = 0 \\ & bD\cfrac = 0 \quad,\quad \frac\cfrac = 0 \,. \end Solution of this system of two ODEs gives : \begin w_x(x) & = \frac\,(3ax^2 -x^3) \\ \theta_x(x) & = \frac\left - \frac\, \left(\frac + \tanh[\nu_b(x-a)right)\right">nu_b(x-a).html" ;"title=" - \frac\, \left(\frac + \tanh[\nu_b(x-a)"> - \frac\, \left(\frac + \tanh[\nu_b(x-a)right)\right \end where \nu_b = \sqrt/b. The bending moments and shear forces corresponding to the displacement w = w_x + y\theta_x are : \begin M_ & = -D\left(\frac+\nu\,\frac\right) \\ & = q_\left(\frac\right) - \left[\frac\right] \times \\ & \quad \left[6\sinh(\nu_b a) - \sinh[\nu_b(2x-a)] + \sinh[\nu_b(2x-3a)] + 8\sinh[\nu_b(x-a)]\right] \\ M_ & = (1-\nu)D\frac \\ & = \frac\left - \frac\right\\ Q_ & = \frac-\frac \\ & = \frac - \left(\frac\right)\times \left 2 + \cosh[\nu_b(3x-2a)- \cosh[\nu_b(3x-4a)">nu_b(3x-2a).html" ;"title="2 + \cosh[\nu_b(3x-2a)">2 + \cosh[\nu_b(3x-2a)- \cosh[\nu_b(3x-4a)right. \\ & \qquad \left. - 16\cosh[2\nu_b(x-a)] + 23\cosh[\nu_b(x-2a)] - 23\cosh(\nu_b x)\right]\,. \end The stresses are : \sigma_ = \frac\,M_ \quad \text \quad \sigma_ = \frac\,Q_\left(1 - \frac\right)\,. If the applied load at the edge is constant, we recover the solutions for a beam under a concentrated end load. If the applied load is a linear function of y, then : q_ = \int_^q_0\left(\frac - \frac\right)\,\texty = \frac ~;~~ q_ = \int_^yq_0\left(\frac - \frac\right)\,\texty = -\frac \,.


See also

*
Bending In applied mechanics, bending (also known as flexure) characterizes the behavior of a slender structural element subjected to an external Structural load, load applied perpendicularly to a longitudinal axis of the element. The structural eleme ...
*
Infinitesimal strain theory In continuum mechanics, the infinitesimal strain theory is a mathematical approach to the description of the deformation of a solid body in which the displacements of the material particles are assumed to be much smaller (indeed, infinitesimal ...
*
Kirchhoff–Love plate theory The Kirchhoff–Love theory of plates is a two-dimensional mathematical model that is used to determine the stresses and deformations in thin plates subjected to forces and moments. This theory is an extension of Euler-Bernoulli beam theory ...
*
Linear elasticity Linear elasticity is a mathematical model of how solid objects deform and become internally stressed by prescribed loading conditions. It is a simplification of the more general nonlinear theory of elasticity and a branch of continuum mechani ...
*
Mindlin–Reissner plate theory The Reissner–Mindlin theory of plates is an extension of Kirchhoff–Love plate theory that takes into account shear deformations through-the-thickness of a plate. The theory was proposed in 1951 by Raymond Mindlin. A similar, but not iden ...
* Plate theory *
Stress (mechanics) In continuum mechanics, stress is a physical quantity that describes forces present during deformation. For example, an object being pulled apart, such as a stretched elastic band, is subject to ''tensile'' stress and may undergo elongati ...
* Stress resultants *
Structural acoustics Structural acoustics is the study of the mechanical waves in structures and how they interact with and radiate into adjacent media. The field of structural acoustics is often referred to as vibroacoustics in Europe and Asia. People that work in t ...
* Vibration of plates


References

{{DEFAULTSORT:Bending Of Plates Continuum mechanics