Technical Guidance and Solutions

Design and analysis guidance and solutions. Technical information about composites and industry solutions.

Posts tagged 'laminate'

Quasi-Isotropy | Wait...what is that?

Composite Design and Analysis Guidance
Category: Analysis | Technical Guidance & Review

Quasi-Isotropy…wait…what is that?

What is it you ask…well, this is one of my favorite meals. A large quasi-isotropy with a side of fries and coke. LOL…but of course is isn’t…actually, this is a laminate that when constructed correctly emulates a metallic material that follows the isotropic relationship defined as: Ex= Ey = Eθ. Quantitatively this can be described using a general rule for a quasi-isotropic layup. Simply apply the following equation that defines the angle between the plies for a symmetric laminate having an identical number of plies at each orientation:

Equation: π/n → n≥3

stiffness  quasi  matrix  laminate  isotropy  composite

2018-01-07 07:24:15
 

Are you Balanced or Unbalanced?

Composite Design and Analysis Guidance
Category: Design | Technical Guidance & Review

Balanced verse and Unbalanced Laminate

So how do we know that we have an unbalanced laminate in the first place? Moreover, if you end up with an unbalanced layup, what are the implications? Good questions to have answers to before signing-off on that laminate design.

Firstly, a perfunctory definition is in order regarding a balanced laminate. A designer will need to ensure that for every -α ply there is a +α ply (with the same material and thickness) somewhere within stacking sequence irrespective of location. Examples of balanced laminates are: [0/30/-30/0] or [45/-45/0/0]. An unbalanced laminate is: [0/30/30/0]...notice that the negative 30-degree ply is no longer present. Now maybe you desire an unbalanced laminate or maybe it’s simply unavoidable but in a majority of design cases this layup scheme should be avoided at all costs. Why? Well, perhaps you have already surmised, this layup scheme has adverse implications, one of them significant…the often dreaded and undesirable in-plane extension-shear coupling.

unbalanced  shear  plate  laminate  extension  coupling  balanced

2017-10-15 22:08:48