Minimum Tape Length Freesize constraint

Andrew Atkinson

Could someone please direct me to documentation relating to what the "minimum tape length" and "tape width" constraints in the composite tab of the free-size optimization options does?

full path in hyperworks 2020.1: Analysis -> Optimization -> Free Size -> Composites

 

Or more specifically, is it required that any tow generated by these options an integer multiple of the minimum length?

It seems to be the case, given the step-wise outlines of the element thicknesses:

Is there a way to set the minimum length, but have the maximum length be a continuous value?

When were these options added? every tutorial I seem to find online does not feature these constraints.

Additionally, what do the offset options: "LOFF" and "WOFF", control in this same tape settings tab?

 

Thanks!

Adriano A. Koga

These are targeted for ATL tape laying machines, so that's why these are fixed width. That's why if consideres integer multiples of the width, as you're laying a tape over each layer.

I think this was added to OptiStruct for a few years now, but maybe later in HyperMesh interface.

Andrew Atkinson

Thank you! Yea I actually used to design ATL/AFP equipment haha, and so am very familiar with the minimum tow length constraint and why the width of each thickness region is an integer multiple of the tape width.

However, it looks to my eye here like the total tow length is also being set to a multiple of this minimum length. Which would be needlessly constraining the design space for the optimization, as in reality the max length could be any value over the minimum, rather than a discrete multiple of the minimum.

It looks to me like as each orientation gains/loses thickness, the tows are starting and ending in lines that are all parallel to each other and the minimum length apart, which I guess I wouldn't expect to be the case by chance, but there's no proof that it wouldn't be.

Is this interpretation of the orientation thickness plots inaccurate? Might this behavior be caused by setting a minimum total laminate thickness? Or is this a deliberate feature of the implemented tape size constraints?

It occurs to me as I write that this may partly be an artifact from the limited color options representing each thickness value, but it's still surprising to me that these color values change along such regular intervals.

Is there any documentation regarding this constraint around I could look at?

 

Thanks again!

Adriano A. Koga

Andrew Atkinson said:

Thank you! Yea I actually used to design ATL/AFP equipment haha, and so am very familiar with the minimum tow length constraint and why the width of each thickness region is an integer multiple of the tape width.

However, it looks to my eye here like the total tow length is also being set to a multiple of this minimum length. Which would be needlessly constraining the design space for the optimization, as in reality the max length could be any value over the minimum, rather than a discrete multiple of the minimum.

It looks to me like as each orientation gains/loses thickness, the tows are starting and ending in lines that are all parallel to each other and the minimum length apart, which I guess I wouldn't expect to be the case by chance, but there's no proof that it wouldn't be.

Is this interpretation of the orientation thickness plots inaccurate? Might this behavior be caused by setting a minimum total laminate thickness? Or is this a deliberate feature of the implemented tape size constraints?

It occurs to me as I write that this may partly be an artifact from the limited color options representing each thickness value, but it's still surprising to me that these color values change along such regular intervals.

Is there any documentation regarding this constraint around I could look at?

 

Thanks again!

I'm sorry. Now i got your question, but i don't have the answer why it looks similar lengths.

I'm not sure how the Free-Size algorithm creates/controls the length of the tape.

Maybe it is creating several small patches, using always the minimum length.

 

 

As for your questions about the offset, a description is found in the documentation for free-size (DSIZE).

Andrew Atkinson

Adriano A. Koga_21884 said:

I'm sorry. Now i got your question, but i don't have the answer why it looks similar lengths.

I'm not sure how the Free-Size algorithm creates/controls the length of the tape.

Maybe it is creating several small patches, using always the minimum length.

 

 

As for your questions about the offset, a description is found in the documentation for free-size (DSIZE).

I'm thinking something similar along the lines of this working by stringing together small patches equal to the minimum length. Which is... unfortunate.

Thank you for directing me to the OFFSET info though! That is helpful in interpreting some of my observed behavior.