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Video 01 - FAQ Explanatory Video

Figure 01 - Compensation

Figure 02 - Coordinate System of Cutting Pattern

FAQ 003216 EN

25 June 2019

Andreas Niemeier Calculation RF-CUTTING-PATTERN Tensile Membrane Structures Form-Finding and Cutting Patterns

How does the flattening process consider the compensation in the determination of cutting patterns?

Answer

The flattening process in the RF‑CUTTING‑PATTERN add-on module is an iterative process that flattens the respective areas of a cutting pattern by minimizing the distortion energy assuming the assigned material behavior.

In simplified terms, the method compresses the initial geometry in a press assuming a frictionless contact until the stresses due to flattening are in equilibrium with each other.

→ See the video

Since this process covers the complete mechanics of the curved structural component, you it is possible to additionally consider the compensation directly as an applied strain load.

Figure 01 - Compensation

Since the strains from the compensation specification interact with the strains from the flattening in the algorithm of RF‑CUTTING‑PATTERN, this kind of compensation consideration cannot be compared with the usual, flat scaling of the non-compensated cutting patterns. The consideration of the complete "cutting pattern mechanics" with all strain terms provides very high-quality geometry of the cutting pattern.

Before the flattening itself, the integral flattening process determines a coordinate system (warp and weft direction) from the mean orientation of FE elements, and uses the initially defined coordinate system with no regard to the respective position of the FE elements in the coordinate system orientation in order to describe the compensation strain and stiffness. Thus, the comparison shown in the video is only valid for an isotropic linear elastic membrane model.

Figure 02 - Coordinate System of Cutting Pattern