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Rectangular Plate - Fixed


A rectangular plate fixed at its edges.

(make-object 'rect-plate ... )

Syntax and Default Values

A 'rect-plate can be created using the following Lisp syntax (the default values are shown for each of the physical parameters):

(make-object 'rect-plate
             (modes 80)
             (length0 .5)
             (length1 .5)
             (thickness .01)
             (density 7800)
             (poisson 0.3)
             (young 2e11)
             (freq-loss 10) 
             (const-loss 10))


The arguments for the physical parameters can be either numerical values or Modalys controllers (either dynamic or constant). If a given parameter is not supplied when using the Lisp syntax, the default parameter value will be used.

  • modes: number of modes.
  • length0: length along the x-axis in meters.
  • length1: length along the y-axis in meters.
  • thickness: in meters.
  • density: in kg/m3. See chart of material properties for appropriate values.
  • young: Young's modulus, in N/m2. See chart of material properties for appropriate values.
  • poisson: Poisson Coeffieient. Usually has a value of 0.3. See general object information.
  • freq-loss, const-loss: loss coefficients. See General object information.

Note that, unlike other objects, the values for freq-loss and const-loss default to 10 for this object.


A rectangular plate can be accessed in its z-direction ('normal) from any point on its surface.

(make-access my-plate my-2D-controller 'normal)
This makes an up-and-down access (in the z direction) at a point on the surface of my-plate. The point is defined by my-2D-controller where the first dimension is x and the second is y (the plate's corners being the points (0, 0), (0, 1), (1, 0) and (1, 1)). For example, in order to access the center of the plate we can say:

(make-access my-plate (const 0.5 0.5) 'normal)



A rect-plate can be tuned to a specific pitch, using the (set-pitch ...) function, by adjusting one of the following physical parameters:

  • 'size
  • 'thickness
  • 'density
  • 'young

Note that for 'size, both the x and y dimensions are scaled together proportionally in order to preserve the harmonic relationships the plate's mode frequencies.

(setq my-plate (make-object 'rect-plate))
(set-pitch my-plate 'size (const 440))

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