Laminate Composites > Laminates theory > First order shear deformation theory
Strain displacement relationship
First-order shear deformation theory calculations are based on a Mindlin assumption which states that sections perpendicular to the reference plane remain planar. This assumption allows one to write:
where:
uo is the reference plane displacement of point (x, y) in the x direction
vo is the reference plane displacement of point (x, y) in the y direction
wo is the reference plane transverse displacement of point (x, y)
The figures below shows the laminate deformed shape in the XZ and YZ planes, respectively.
The strains are then calculated by differentiating the displacement functions:
These equations can be rewritten in the form:
where εx0, εy0 and γxy0 are called the mid plane strains and:
are called the curvatures. Positive curvatures are shown in the figure below.
Transverse shear deformations are given by:
Note:
In CLT, both γxz and γyz are neglected.
Look up more details
First order shear deformation theory
Constitutive equations
Off-axis relationships
Shell stress resultants
Laminate stiffness matrices
Transverse shear stiffness matrix
Shear deformation theory references
Quick links
Command reference
Pre/Post video examples
Bulk Entry Descriptions
Simcenter 3D tutorials
Browse Simcenter 3D help by product area
Strain displacement relationship, Simcenter 3D 2021.1 Series
© 2020 Siemens
window.mainLanguage="en_US"
window.delivId=""
window.projectId=""
MathJax.Hub.Config({ TeX: { extensions: ["autoload-all.js"] }, tex2jax: { displayMath: [ ] }, "SVG": { scale: 125 } });
Source: https://docs.sw.siemens.com/en-US/doc/289054037/PL20200601120302950.advanced/id626876 · retrieved 2026-07-17