3.7.1.3: Deformation-Energy
In mechanics, energy is equal to force times displacement parallel to its direction. Think of a rubber band: If you stretch it, you do work on it. This work gets stored inside the rubber and can be transformed into other kinds of energy. You may for example launch a small toy airplane with it: Then the elastic energy in the rubber gets transformed into kinetic energy. When stretching an elastic material, the force to be applied at the beginning is zero and then grows proportionally to the stiffness and the increase of length of the material. The mechanical work is equal to the area beneath the curve that results from drawing the magnitude of the applied force over its corresponding displacement. In case of linear elastic materials this gives a rectangular triangle with the final displacement forming one leg and the final force being its other leg. This shows that for equal final forces the elastic energy stored in a material decreases with decreasing displacements which corresponds to increasing stiffness.
Fig. 3.7.1.3.1 shows a simply supported beam with two load-cases. The model gets first passed through a "Load-Case-Selector component" which sets the model's default selection to the minimum and maximum result envelope. Thus, when the model enters the "Deformation-Energy"-component via the "Model"-input there is no necessity to supply an additional load-case-selection string via the "LCase" input-plug. If supplied, a "LCase"-input sets the model's new default load-case selection. With the input “Elems|Ids” one can supply identifiers od elements of those parts for which the deformation energy shall be calculated. An empty list means that all elements are considered. "nInt" controls the number of segments along each beam for doing the numerical integration of the elastic energy. It defaults to two but should be set to a larger number for higher accuracy in case of multiple loads along an element.
The structure of the data trees returned from the component contains one branch for each element and sub-element. A sub-element is e.g., a face of a shell. In fig. 3.7.1.3.1 the second number from the right of the data-path corresponds to the element index. Since beams do not have sub-elements the last path-number is always zero in the above example. The numbers in each branch belong to the minimum- and maximum results. This corresponds to the selection in the Load-Case-Selector-component.
The "Ax-Energy"- and "Be-Energy"-outputs deliver the axial deformation- and bending energies. Have a look at "Ax-LCaseInd" and "Be-LCaseInd" in order to see from which load-case within the load-case-combination "LCC" the results in "Ax-Energy"- and "Be-Energy"- outputs derive. Since LCC = LC1|LC2 ("|" stands for "or") the iondexes are either "0" or "1".
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