Technical Articles and Engineering Guidance

Engineering solutions and guidance for the design and stress engineer. Leverage technical articles to facilitate and expedite engineering tasks. Search and procure information expeditiously by exploiting web-centric database containing thousands of technical articles. Download free software to assist in the quantification of composite and metallic related problems.

Analysis | Technical Guidance & Review

Analysis | Technical Guidance & Review

2 posts in this category

The Free Edge Effect

The free edge effect is an inter-galactic phenomenon found on the outer reaches of the cosmos that leads to a parallel…well…no, not exactly. What I’m referring to is a region within a laminate that produces a fully three-dimensional stress field at the free edge, then decays quite rapidly to a two-dimensional stress field as the distance from the free edge increases. The three-dimensional stress field is responsible for delamination at a free edge, and is commonly referred to as inter-laminar stresses. A composite analysis is typically confined to classical lamination theory. Unfortunately, this assumes that all out-of-plane stresses are zero, making the determination of transverse stresses impossible. Consequently, this assumption is not valid when one is interested in calculating out-of-plane stresses in regions near or at a free edge. 

stress  Poisson  notch  inter-laminar  free edge  cutout

2018-07-05 22:34:25
 

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

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
 
Quick-Pick Article