Home > Knowledge > How useful is Tensile Strength data ?

How useful is Tensile Strength data ?

This article on tensile strength was written by Dr.Charlie Geddes for Hardie Polymers.

When scanning a thermoplastics data sheet for a new project or finding a replacement for an existing grade, the eye tends to get drawn to the values quoted for tensile strength (or more correctly ‘tensile stress at break’) as an indication of the material’s mechanical properties.  Although tensile stress is a useful property for metals, it is of less value when dealing with thermoplastics.  Applied loads during product service life are more likely to be in compression or in bend than in pure tension… with a few notable exceptions.  Secondly, rupture under an applied tensile load is very seldom the cause of product failure in a plastics component.   A more likely cause is unacceptable deformation or distortion. That is an entirely different property, related to the tensile or flexural modulus (stiffness) and component geometry.

Tensile Testing Machine - tensile strength

Another reason for not reading too much into tensile strength data?  The value listed in data sheets is a snapshot. It is derived from a standard test. This is carried out under a specific combination of temperature and strain rate. (This is the rate at which the test piece is stretched).  Changing temperature and strain rate can significantly alter the resulting value for tensile strength (and also the elongation at break).  The ultimate elongation is also influenced by the presence of flaws and imperfections in the material.

Is the product is going to be subjected to mechanical stresses during its service life? It would be prudent to pay more attention to the values of modulus (stiffness) and impact data rather than tensile strength. However, data for impact can give a false sense of security and needs careful interpretation.

tensile graphs

Written by Dr.Charlie Geddes for Hardie Polymers

For more of Charlie’s blogs why not read more our our knowledge base articles?

For information on all the specified grades that we can offer please contact us today or also try our polymer search.

Posted in Guides,

Find the exact grade you require

Improve on your current price

Get the material you need faster

Our no risk Polymer Search

  • We’ll conduct a no obligation search so you don’t have to
  • We can supply the exact grade you need so you can meet your spec
  • Minimum quantity is just 25kg so you can get just what you need
  • If we can’t find your grade of plastic there is no cost to you
  • Products can be dispatched by express shipping if required

Chat to us first as we’re happy to answer any of your questions.


Request a Quote

  • Our team are available from 8am-5pm and we always aim to get back to you the same day. If you would rather contact us immediately please join us on live chat
    or give us a call on 0141 952 1900.
  • This field is for validation purposes and should be left unchanged.