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The directional dependent Tsai-Hill Failure Criterion allows to set-up different Tension Strength for the build direction (axis) and the In-plane directions as well as the Shear Strength. The FFF Thumb Rule is based on it, in contrast to it the Shear Strength isn’t calculated automatically based on the Thumb Rule.
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X: Maximum allowable Stress (Stress Goal) in build direction (x)
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S: Maximum allowable Shear Strength (Stress Goal)
Directional Dependency (Tsai-Wu)
With the directional dependent Tsai-Wu Failure Criterion the difference between Tensile and Compression Strength can be considered besides the directional dependency.
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X_t: Maximum allowable Tension Stress (Stress Goal) in build direction (x)
X_c: Maximum allowable Compression Stress (Stress Goal) in build direction (x)
Y_t: Maximum allowable Tension Stress (Stress Goal) in in In-Plane directions (y,z)
Y_c: Maximum allowable Compression Stress (Stress Goal) in in In-Plane directions (y,z)
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Comparison of the different Failure Criteria
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