Plastic Stress in Metals Calculator v1

Price: £25.41 (£25.41 Inc. VAT)
Plastic stress calculator


The outer fibres of a beam or plate will deform plastically if exposed to excessive bending moments with which the thickness of the plastically deformed section increases. Ultimately, the beam will generate a plastic hinge when the bending moment is such that the plastically deformed sections converge at the neutral axis.

Plastically deformed material in a beam need not be considered as an operational failure. A successful ultimate limit-state design scenario can show that a beam or plate has deformed plastically on the understanding that the surrounding structure remains intact.

This type of calculation is difficult to perform in Frame or FE type software and requires specialist knowledge of their use. You can take the bending moments from a frame analysis and use ElastiPlast to see in seconds if the element has deformed plastically.


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The plastic stress calculator includes four calculation options; Rectangular bar or plate, rectangular hollow sections, tubular sections and I or H beams
(see CalQlata’s Steel Beam Sizes)

ElastiPlast calculates the bending moment required to achieve yield stress in the outermost fibres of a section, the bending moment required to achieve a plastic hinge and the moment required to achieve yield stress at a radial distance from the section’s neutral axis. The plastic stress calculator also lets you know how much of this bending moment is generated by elastic resistance and how much is generated plastically.

For help using this calculator see Technical Help

Plastic Stress (in metals) Calculator - Options

The plastic stress calculator includes calculation options for the following beam sections:

Plain rectangular plate or bar

Hollow circular tube

Hollow rectangular tube (RHS)

I-Beam or H-Beam

All the above calculation options have the following common input and output data:

You enter and the plastic stress calculator will provide:
  • Yield stress
  • Ultimate tensile stress
  • Elastic stress boundary (‘y’)
  • Bending moment for ‘y’
  • Elastic moment
  • Plastic moment
  • Minimum plastic moment
  • Plastic hinge moment

With the following additional input data for each of the above calculation options:

You enter:
  • Plain rectangular plate or bar: Thickness, Width
  • Hollow circular tube: Inside Diameter, Outside diameter
  • Hollow rectangular tube: Height, Width, Wall thickness
  • I-Beam or H-Beam: Height, Width, Flange thickness, Web thickness

Check minimum system requirements

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