Category: ESAComp

ESAComp introduces “through-the-width” debonding/delamination analysis

By Markku Palantera on September 12, 2017

Markku Palantera

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Delamination is a recognized, major failure mechanisms for composites. The separation of the internal layers within a composite, caused by high through-the-thickness stresses, can arise due to manufacturing defects or from impacts occurring during assembly or whilst in-service. Delamination can … Read More

structure lead

Structures are not ideal – Challenges of buckling analyses

By Markku Palantera on October 15, 2015

Markku Palantera

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The linear buckling analysis is widely used for determining the load level at which the structure loses its stability. In reality, structures may be sensitive to even small imperfections in their shape, which is accounted for by applying large factors … Read More

Nonlinear collapse analysis of a launcher structure with imperfection sensitivity study

By Markku Palantera on March 5, 2015

Markku Palantera

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A thin-walled axially compressed CFRP cylinder was studied using the large deformation analysis. Different numbers of axial, circumferential and combined imperfection waves were used to represent the initial shape of the structure. Three examples are shown at the bottom of … Read More

Thin-walled cylinders are sensitive to imperfections

By Markku Palantera on February 20, 2015

Markku Palantera

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Decreased buckling loads and geometrical imperfections are closely related for thin-walled cylinders. By definition, a geometrical imperfection is a deviation from the perfect cylindrical geometry. An example is shown in Figure 1. Geometrical imperfections have been demonstrated to have clearly … Read More

Quick and clean technology for composite cylinder stability analysis

By Markku Palantera on February 17, 2015

Markku Palantera

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Thin-walled cylindrical shells (radius-to-thickness ratio of 160-500) under different loading conditions have been studied for structural stability (Figure 1). Based on this study, guidelines for the selection of the element mesh density have been set. A set of problems presented … Read More

Making a laminate twist

By Markku Palantera on March 20, 2013

Markku Palantera

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The properties of fiber-reinforced composite structures can be tailored with layer orientations and stacking sequence. For example, you can design your laminate so that under a tensile load it twists, but at the same time it does not bend nor … Read More

delamination stresses

At the origins of delamination stresses – Free edge analysis gives insight

By Markku Palantera on January 12, 2013

Markku Palantera

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When you make a tensile test for [±45/0/90]s and [90/±45/0]s laminates you may observe different failure strengths. This may seem first surprising since the laminates are basically the same – only the stacking sequence is different, which should not influence … Read More