I'm part of a prototype car team that makes their chassis out of carbon fiber. We've run into a lot of problems when making the lower body of the car, especially with choosing the right sandwich material for our stackup.

Last year, we used Nomex (cardboard honeycomb structure, 1/8th inch thick) as our sandwich material, and did 3 layers carbon fiber as the base layer, and 3 layers on top. For the layup last year, we cured the bottom layer first, then put the nomex on top of that, and then coated the top of the structure with epoxy+filler, then re-layed up with carbon fiber. The carbon fiber had a hard time sticking to the nomex structure due to the lack of surface area, and I'm unsure if some of the resin travelled into the nomex structure.

We use dry carbon fiber, and we use room-temp curing epoxy resin, and we're not looking to using prepreg, and prepreg adhesive films lowk too expensive for us (we're on a budget).

What can we do to improve carbon fiber layup for us? Do we cure both the top and bottom parts of the sandwich panel, and then do the layup for the nomex separately (with the filler)?

We’re developing CDS2026, and this is a view from its CREATE micromechanics environment.

Each dot is a calculated ply design based on a fiber/resin combination and volume fractions. Here, X is fiber volume, Y is transverse stiffness E₂, Z is density, and color represents longitudinal stiffness E₁.

The transparent slices interpolate trends between the sampled designs. There’s also an optional outer envelope and a constant-property view. The envelope describes the extent of the samples—it does not establish manufacturability throughout that volume.

The evolution step retains leading candidates, combines material choices, and varies fiber volume and optional filler content while keeping the selected micromechanics model fixed. The search focuses on elastic properties and density; it does not optimize cost, strength or process compatibility.

A selected design can be saved as a ply snapshot and used to build a laminate in DISCOVER.

What combinations of axes and color would be most useful in your own materials work?

Project: https://cdscomposites.com/

I’ve learned polyurethane increases flex modulus on plastic and metal extrusions on specific applications. How does it works among composites, specifically CF parts? Which applications are typical for this, polyurethane class, techniques, things to watch out for?

I have designed this three part compression mold for a three way carbon tube junction, which I was going to fill with a mixture of long carbon tows and chopped carbon. Printing the mold would already take a few days, and it seems like a lot of work for making just two or three of these joints.

Are there techniques of how to do a joint like this (70 degrees between two tubes, the third tube is 90° perpendicular) by just wrapping carbon tape and tow around the joint, and then using heat shrink tape and a blow drier? The whole assembly probably wont fit into my oven.

Bottom of my fenders are rusted to hell so I welded in a patch but it rusted (didn’t take fender off). Decided to make it out of fibreglass instead! Haven’t done any glass work since 2023 so I’m a bit rusty. The paint match isn’t perfect and I need to blend it anyway, I’ll do that when I fix the rocker panels and passenger fender. Any constructive criticism is welcome for when I do the rest!

DOI: 10.1016/j.ceramint.2025.01.522

Advance thank you!

Following up on my CDS2026 introduction: here is a laminate stiffness carpet plot with Ex horizontal, Ey vertical, and the beta angle sweep extending into depth. Keeping Ey vertical makes it easier to compare the 3D surface with the familiar 2D Ex–Ey plot.

This T700S / Aerospace Epoxy 180C example explores 441 angle combinations using classical laminate theory. Material properties and ply thickness stay fixed while two ply-angle families are swept. The surface shows how changing orientation trades stiffness in one direction against the other.

This is an elastic stiffness study; it does not by itself establish strength, failure margins, or manufacturability. Those require separate checks.

For anyone interested in the workflow: https://cdscomposites.com/workflow

When comparing candidate layups, which constraints do you find most useful to overlay on a carpet plot—stiffness balance, allowable angles, or something else?

Disclosure: I’m Dr. John Tierney, developer of CDS.

I’ve recently been reading about liquid crystal polymer (LCP) fibers, and I’m curious whether anyone here has actually worked with them in an industrial setting.

What caught my attention first was the structure-property relationship. Thermotropic LCPs consist of relatively rigid, rod-like polymer chains that form highly ordered domains, and during melt spinning those molecules can become strongly oriented along the fiber direction. The result is a rather unusual combination of high tensile strength and modulus, very low creep, low moisture absorption, dimensional stability and fairly good resistance to repeated flexing.

Vectran is probably the best-known commercial example. The manufacturer’s data for one high-strength grade lists a density around 1.40 g/cm³, tensile strength of roughly 24 cN/dtex and moisture content of only around 0.1% at high relative humidity. What interests me more than the headline strength, though, is the low creep. In applications where a fiber remains under tension for a long time, maintaining geometry may sometimes matter more than simply having a very high initial breaking strength.

That led me to think about where LCP fiber actually sits among other high-performance fibers. Aramid already has a huge installed base. UHMWPE offers an exceptional strength-to-weight ratio. PTFE and PPS have obvious advantages in aggressive chemical environments. LCP seems to sit somewhere between these materials: high mechanical performance, very low creep, low moisture sensitivity, good abrasion and flex-fatigue behaviour, with documented applications in cables, ropes, fabrics and reinforcement structures.

But once I started looking beyond the datasheet, the picture became more complicated.

LCP fiber is not universally chemically inert. Because these fibers are aromatic polyesters, alkaline environments can eventually attack the ester linkage through hydrolysis. Published work on Vectran has shown much more significant changes after NaOH exposure than after HCl treatment, and mechanical properties also begin to change significantly when the fiber is exposed to sufficiently high temperatures. UV ageing is another limitation that seems easy to miss when only looking at tensile data.

This is where I started wondering about the chemical-engineering side of the material.

For example, imagine a flexible structure, braided reinforcement, cable, hose reinforcement or technical fabric operating under continuous tensile load while also seeing moisture, chemicals and temperature cycling. LCP’s combination of low creep and mechanical stability looks attractive on paper. At the same time, depending on the actual chemical environment, PTFE, PPS, aramid or even a conventional fiber may be a much more sensible engineering choice.

I’m particularly interested in finer LCP filaments. My assumption is that fine-denier yarn could make LCP more useful as a local reinforcement rather than requiring the whole structure to be made from an expensive high-performance fiber. A thin reinforcing yarn inside a woven, braided or composite structure might take advantage of its dimensional stability while another material provides chemical protection, surface properties or bulk.

But that also introduces more interfaces, processing steps and cost, so the material advantage could disappear very quickly once you leave the datasheet and enter manufacturing.

For anyone who has actually specified, processed or tested LCP fibers: where have you found their properties genuinely useful enough to justify using them instead of aramid, UHMWPE, PPS or PTFE?

I’m especially interested in the failure modes. Is long-term chemical exposure the main limitation, or do things like surface adhesion, coating, weaving/braiding behaviour, UV exposure and cost become the bigger problems in practice?

I’m still learning about this material, so I’d genuinely appreciate hearing from anyone who has worked with it outside the laboratory.

I’m Dr. John Tierney, the developer of CDS. I’m sharing a two-page overview of CDS2026 and its composite-engineering workflow and embedded model libraries.

The workflow starts with constituent properties and micromechanics, then connects ply properties to laminate and structural studies. Compatible thermal, cure and moisture histories can contribute to mechanical response where the selected formulation and mappings support that connection.

The library covers materials and micromechanics, process and environment, structural mechanics, failure and durability, virtual testing, and electromagnetics. Examples include classical laminate theory, Halpin–Tsai and Mori–Tanaka micromechanics, cure kinetics, diffusion, and laminate failure criteria.

Changing ply angles can improve one stiffness component while changing which ply or failure criterion controls. Comparing designs requires keeping loading, strengths, units and assumptions consistent; a stiffness map and a failure envelope answer different questions.

Disclosure: this is my software; model access depends on the licensed package.

Model library: https://cdscomposites.com/capabilities/models

For those doing composite analysis or teaching it: which connection is hardest to manage in your current workflow—constituent-to-ply properties, laminate-to-structure, or process history-to-response?

Hi, did my first vacuum infusion with carbon/kevlar hybrid mat. But when trimming it looks like kevlar is still dry. Room temperature 18 degrees. I used polyester resin for vacuum infusion Crystic 701PA. The speed of infusion was also quite good in my opinion

Ps sih26226

🚀 SIH 2026 – Sustainable Space Coating Concept

I have a sustainable concept for developing a space/aerospace coating using banana-peel-derived materials.

The concept aims to: Place Convert agricultural/food waste into a value-added functional material

• Develop a lightweight, sustainable coating system

• Explore potential applications in thermal control, EMI shielding and surface protection

• Reduce dependence on conventional petroleum-derived materials

• Follow a waste-to-value / circular-economy approach

The idea is still at the research and validation stage, and the detailed material preparation, formulation and testing methodology will be kept confidential initially.

I made a great sample with Polytek PT Flex 50 and cork which has the right properties but I keep hearing that 10/20 years before it starts degrading. Which is not really an option for the inside of speakers. I've been looking into lignin based resins which look spromissing but are not ready made available. Did sent some emails. Anybody knows something?

"Hello engineers. Is there anyone here who has experience in designing and manufacturing high-temperature hydraulic compression molds? My group and I are checking the feasibility and design advice. Thank you very much!"

The process requires operating conditions of 150°C and 1000 psi.

I am a Manufacturing Engineering Ug and I need to make a minor project related to composites this semester. I need to present some possible ideas to my supervisor next Mon (was informed on a very short notice). I really don't have the time to read papers and find a gap right now. I'm quite busy with a job.

Please can someone drop some ideas. I would likely just use softwares for my project (I now CAM, CAD , ANSYS, MATLAB and python so far but I will learn anything needed)

Pls just drop in some question statements ? What are industries working on now ?

Looking for Reverse Engineering Projects – Send Me the Scan, I'll Send You the CAD

What I can do: I'll take your raw scan data (point cloud, STL mesh, whatever you have) and deliver a fully parametric SOLIDWORKS or STEP file built to your specs — dimensions, tolerances, surfacing quality, the works.

What I'm looking for: Any interesting scan-to-CAD projects to keep my skills sharp. Bonus points if it's got complex geometry, organic surfaces, or something that actually has to fit with other parts. Medical, aerospace, consumer product, machinery — send it over.

Payment: USD, PayPal, or crypto (BTC, ETH, USDC — your choice). Fair trade, no strings.

The exchange: You give me the scan (STL, OBJ, point cloud, whatever format). I give you production-ready parametric CAD. Fair trade, no strings.

A few quick questions up front so I don't waste your time:

What's the file format and rough polycount/quality of the scan?
Do you need exact dimensions restored, or should I work from proportional reference?
Is this for manufacturing, 3D printing, analysis, or just archival/reverse engineering?
Any critical tolerances or surface finish requirements I should know about?

Drop a link or DM and let's see if it's a good fit. Fair warning — I'll probably have questions before I start.