Training Module #8: Composites - Producibility

Consider the example below. Zone 2 is narrow, and there is not much room to ramp down or up in thickness. Minimum manufacturable thickness is greater than mass optimum thickness.

You can use HyperX to enforce ply-drop ratios between Zone boundaries to prevent situations like above and make your design more easily manufactured.

HyperX provides producibility scoring for Plies during Sequencing and within Laminate Design Study tools.

Use Laminate Families to (1) ensure compatibility between Laminate results of neighboring Zones, and (2) implement pre-defined Ply drops/adds.

The HyperX Sequencing process studies many, many different Ply results to find the most manufacturable solution (considering details such as ply drops, ply count, and ply size).

Laminate Families can be imported from Excel spreadsheets that have been formatted to match the HyperX Laminate Family format, which is shown in the image below. Rather than formatting the spreadsheet from scratch, it is often easier to Export a Laminate Family from HyperX to create a template for the spreadsheet. The exported spreadsheet can be populated with the user's Laminate Family and then imported.

To "create" a Laminate Family is to manually define the Main Stacking Sequence (MSS) and corresponding Family Members from scratch. This involves creating individual Plies (rows) and Laminates (columns). This is particularly advantageous if your team or program already has a standard Laminate Family.

In many cases, programs have very specific laminate Ply Angle % and Layup Rule requirements. Or perhaps there is an interest in implementing double-double laminates, rather than the traditional 0/45/90. In these cases, it may be beneficial to skip any preliminary Sizing and go straight to Sizing with a Laminate Family. This requires generating Laminate Family(s) based solely on the rules defined, rather than any existing entities (Sizing results, FEM imported Laminates, Plies).

Generate a new Laminate Family and assign to Zones based on the Plies in the Ply Manager. These Plies may have been imported from CAD or created/generated by other methods. Each Sequence will be a layer in the Laminate Family’s MSS. Every unique stack generated by various Ply coverages will be a Candidate Laminate in the Family.

In many cases, the Laminates defined in the FEM are representative of those that are considered 'acceptable' by the program. However, even with predefined Laminates, there is likely still room for Sizing in terms of which Zones are assigned which Laminates. In this case, it is beneficial to reverse engineer a Laminate Family - which can be used for Sizing - from existing Laminate definitions coming from the FEM.

The primary drawback of Sizing with Laminate Families is that they can result in higher weight than a “free” Sizing, where each Zone in a Structure can choose a Laminate that has been developed specifically for the loads in that Zone. HyperX addresses this shortcoming by piggy-backing off of preliminary Sizing results to produce a Structure-specific Laminate Family. This is done by aggregating preliminary Sizing results for each Zone and generating a MSS that incorporates those solutions, followed by the Ply Drop generation which populates the family.

There are a few different ways to use Sizing Results to generate Laminate Families. First, you must choose how to generate the Main Stacking Sequence (MSS) based on the Sizing information available and/or the structural concept you are analyzing. Once you have the MSS, you will choose how to generate the Laminate Family by selecting a Drop Pattern, Layup Rules, and Permutations to use when generating the Candidate Laminates in the Family.

MSS Generation Methods

The table below indicates which methods are compatible with the various composite concepts available in HyperX, for each Sizing Mode. "DS with ELs" indicates Detailed Sizing with Effective Laminates and "DS with DLs" indicates Detailed Sizing with Discrete Laminates.

Description of MSS generation methods:

• Unstiffened Laminate - Uses stacking sequence information from the selected Zones to generate an MSS that is tuned for those Zones. For example, if the majority of selected Zones have a high number of 45° Plies near the outside of the Laminate then the resulting MSS will reflect that trend. Another feature of this MSS method is that the Rapid Sizing Laminate for each Zone is a subset of generated MSS. This often results in an MSS that is 1.5-2X thicker than the thickest input Zone. However, this is not a problem for with the resulting Laminate Family because Detailed Sizing will just not use the thicker Laminates in the Family.

  

• Homogenized Unstiffened Laminate - Similar objective to the method above, but with a different algorithm. This method attempts to smooth out the distribution of different ply orientations through the thickness of the MSS using histograms of ply orientation placement collected from all of the input Zones.

  

• Stiffened Laminate (Default) - Uses only ply count information from the selected Zones to generate an MSS that is tuned for those Zones. If the selected Zones have a higher percentage of 0° Plies for example, the resulting MSS will also have a higher percentage of 0° Plies (Zones are weighted based on area and thickness). This method will put the most prevalent ply orientations towards the outsides of the Laminate.

  

• Homogenized Stiffened Laminate - Similar objective to the above, except that this method attempts to homogenize the stacking sequence. For example, if all of the selected Zones happened to have an equal count of 0°, +45°, -45°, and 90° Plies, then the MSS would have a repeating pattern of [0/45/-45/90] throughout.

  

Family Generation Methods

The Laminate Family generation methods all produce a series of Laminates in a Family based off of the MSS. All methods take the MSS as the thickest Laminate in the Family and produce progressively thinner subsets of this Laminate based on a Drop Pattern and subject to the Layup Rules and Permutations.

Drop Patterns

• Triangle - Plies dropped from top to bottom going from thickest to thinnest Laminate.

• Upside-Down Triangle - Plies dropped from bottom to top going from thickest to thinnest Laminate.

• Diamond - Plies dropped from outside to inside going from thickest to thinnest Laminate.

• Hourglass - Plies dropped from mid-plane to outside going from thickest to thinnest Laminate.

• Interleaved - Ply drops arranged to minimize number of consecutive drops. Plies at the top, bottom, and mid-plane are carried through from thickest to thinnest Laminate.

• Interleaved Hourglass - Ply drops arranged to minimize number of consecutive drops. Plies at the top and bottom are carried through from thickest to thinnest Laminate

Layup Rules

Layup Rules are enforced through the Family generation process. If possible, the Family “shape” will be modified to accommodate the Layup Rules (symmetry, balance, max adjacent plies, ply %, etc.). If it is not possible to make a Laminate of a given thickness while maintaining the rules, it is skipped in the final Family produced.

Permutations

Two "Permutations" are available while producing Laminate Families. These work by producing the “Base” Families (with the Drop Pattern and applied Layup Rules) and creating additional modified copies. Both are intended to produce additional variety in the Families which can reduce manufacturing complexity at little or no sacrifice in weight.

• Ply Skip – Omit entire sequences in the Family.

• Midplanes – Increase coverage of midplane ply in the Family (if present).

Selecting multiple Drop Pattern and Permutation options generates many, many Laminate Families. The Design Study tool is a way to quickly identify Laminate Families that achieve the lowest possible weight with a target level of producibility.

The quickest and most robust Sizing approach recommended by Collier Aerospace engineers is sizing with Laminate Families - where the optimum Sizing result for each Zone is chosen from a predefined selection of Candidate Laminates. Since a Laminate Family consists of Laminates that are related to one another, a design with optimum weight and manufacturability is obtained in less steps.

Once you've selected a Laminate Family to use, assign it to desired Zones via Design Property and Size. For a more detailed tutorial see: How To Size with Laminate Families.

The HyperX Sequencing process studies many, many different Ply results to find the most manufacturable solution (considering details such as ply drops, ply count, and ply size). Additionally, Sequencing can trade weight vs manufacturability by swapping out Laminate results for Zones to find solutions that have better compatibility with adjacent Zones. The image below shows 3 adjacent Zones with Laminate results from Zone Sizing.

Once Global Plies have been produced by Sequencing, they can be reviewed and managed in the Ply Manager. Plies can be used to inform Analysis, map as-manufacture fiber directions, and view those on the model. Plies can also be imported from and exported to CAD software so you can combine that with the ability to generate Laminate Families from Plies to make a workflow that tightly incorporates your design and manufacturing software (making them a key part of how HyperX can fit into the Digital Thread).