Determining Ultimate Strength Loads

[Anonymous]

Does Composite Design determine what the ultimate strengths of a part will be?  It gives first ply failure, but does it give the ultimate failure loads?

[dean.rose]

Yes Paul it does. In the laminate properties module you can view the first ply failure stresses or do a progressive failure analysis. The Progressive Failure feature is used to determine the progression of individual ply failures and the associated progressive laminate stiffness degradation that occurs as the laminate is progressively subjected to a set of user-specified loads. 

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[Anonymous]

But we want to determine what the maximum tensile and longitudinal strengths are for a laminate that I designed.  It is a property of the wind sequence created by me, not the user-applied loads or cross sectional area of the composite.  I am looking for exactly what the FIRST PLY FAILURE SURVEY gives you.  You enter in the laminate sequence (created by me) and then the program tells you what stresses that the first ply of composite will fail at.  I want that to go farther and tell me what the ultimate tensile and compression stresses will be on this tube.  Really I need a last-ply failure survey.  Does Simulation Composite Design do that? 

[dean.rose · Accepted solution]

Hi Paul,

These are great questions. Let me clarify a bit. Depending on the design requirements you have SImulation Composite Design offers two options. Many of our users often have design criterion driven by first ply failure. First ply failure will give you the volume averaged axial tensile strength, axial compressive strength, transverse tensile strength, transverse compressive strength and in-plane shear strength of the laminate. For each of the five fundamental strengths, Simulation Composite Design lists the first ply to fail in the laminate and possibly the mode of failure if the applicable failure criterion is selected.

From the description you provided it appear you are interested in our Progressive Failure feature. You are allowed to put in the loads you would your material to undergo. Based on that loading the Progressive Failure feature will determine the failure of each individual ply. In addition to failure it reduces the stiffness of each failed ply to more accurately determine the material response as it continues to be loaded.

You are allowed to select the failure criterion, location for failure evaluation, degradation factors. Upon calculation you can view a tabulated output with stress and strain outputs, failure indices and factor so safety. When a ply fails the entry is highlighted, the failed ply is indicated along with the associated failure mode.

In addition to this output you will be excited to see a graphic plot of the stress strain presented in the tabular format. This is often a more useful representation of the data to quickly understand the response.

You can easily extract areas where there are initial ply failures as well as the loading that causes ultimate failure of the specimen. You can easily turn back to the tabulated data to extract additional failure about failed plies, stresses and the modes of failure.  I hope this clears things up. I invite you to try these features for yourself by downloading the free trial of Simulation Composite Design.

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