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Background

Looking to build a table for a dryer to fit inside a laundry closet. The table must be assembled inside the closet, as such it has three parts: two legs and a metal sheet for the table top. Here's a picture of the table outside the closet:

laundry closet washer

Here's a picture of the dryer on top of the table:

laundry closet washer and dryer

Weights, Measures, and Materials

Dryer

  • Dimensions: 65.5cm x 60cm
  • Weight: 50kg

Table

  • Dimensions: 106cm x 63.5cm
  • Material: Steel alloy

Table Dimensions Wireframe

Same, but without the wireframe:

Table Dimensions

Without the table top to show the supporting flaps:

Table Flaps

Problem

I'm concerned that the table thickness will be insufficient to support the load. A flat plane deflector calculator is useful for calculating the total load applied to center of plate, but doesn't quite tell me if the distributed load of the dryer (not a point load) will be structurally sound.

In comparison, commercial heavy gauge machine tables support over 900kg, so it looks like the design is sound.

Question

Are these calculations reasonable? (Especially pertaining to the forces imparted by the dryer?) That is, will a 1.25cm (approx. ½") steel alloy table top outlast the dryer?

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    $\begingroup$ Most appliances will not create a distributed load over the plate. The appliance usually stands on feet (e.g. one at each corner) which may be adjustable to deal with the situation where the floor of the room is not perfectly flat. For a safe design, you also need something to restrain the dryer from "walking off the shelf" if it vibrates when in use. $\endgroup$
    – alephzero
    Commented Feb 20, 2017 at 6:23
  • $\begingroup$ Let me just say that the load applied to center of the plane is the worst case - highest torque, highest load. If your flat plane deflector calculator tells you the table will withstand load equivalent to weight of the dryer applied to the center, the table will withstand every other distribution of that load. $\endgroup$
    – SF.
    Commented Feb 20, 2017 at 12:32
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    $\begingroup$ i have to ask as someone with several years experience as an engineer in product development of consumer laundry appliances, why on earth would you do this? Modern front loading washers and dryers are designed to be stackable and fastened together in a way that allows safe installations just as you show with no table/shelf needed. $\endgroup$
    – DLS3141
    Commented Feb 21, 2017 at 0:59
  • $\begingroup$ Get a real appliance dolly with a strap. Easy peasy. Cheaper and safer too. uline.com/Product/Detail/H-5047/Hand-Trucks/… $\endgroup$
    – DLS3141
    Commented Feb 21, 2017 at 3:33
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    $\begingroup$ Concerns about vibration ARE related to the question. The cyclic stresses induced by the dryer's vibration can and will cause failure of the overall structure, especially if you were to build this from aluminum which has no real fatigue limit. $\endgroup$
    – DLS3141
    Commented Feb 21, 2017 at 14:48

1 Answer 1

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Based on the numerous helpful comments, I've settled on the following design.

After researching structural integrity of steel alloys, my understanding is that fatigue failure due to cyclic stresses can be eliminated by ensuring that the endurance limit of the alloy is higher than the cyclic forces the dryer will impose. I've also read that some steel alloys will not fatigue regardless of the number of cycles.

Here are my assumptions:

  • Point load = 35kN (estimated)
  • (x, y) offset to the right of the table top
  • Dimensions = 64cm x 106.5cm x 1cm
  • Young's modulus = 200GPa
  • Poisson's ratio = 0.287

The (x, y) stresses are therefore (193MPa, 113MPa).

Structural steel (ASTM-A36) has a yield strength of 250MPa and tensile strength of 400MPa. AISI 8620 is 385MPa/530MPa, respectively. At 2cm thickness, the point load would have to exceed 140kN for the same stresses as 1cm, thus a ½" thickness for the table top should not have its endurance limit exceeded by the dryer's cyclic stresses.

Laundry pads prevent walking and reduce vibration. The end result will resemble (pads not rendered):

Table w/Dryer

Instead of an X brace, I've opted for two horizontal braces.

Table without Dryer

Without the top, it'll look like:

Table without Top

The metalworker decided simple was best and basically welded a table together inside the closet:

Finished table

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