¶ title: 2023_ST_TN_A02_CFRP_Rods
description: Link: https://rocket-team.epfl.ch/en/rocket_ss/structure/Nordend/2023_ST_TN_A02
published: true
date: 2025-05-21T19:10:02.755Z
tags:
editor: markdown
dateCreated: 2023-08-18T09:25:33.298Z
¶ title: 2023_ST_TN_A02_CFRP_Rods
description: Link: https://rocket-team.epfl.ch/en/rocket_ss/structure/Nordend/2023_ST_TN_A02
published: true
date: 2024-12-30T21:17:34.010Z
tags:
editor: markdown
dateCreated: 2023-08-18T09:25:33.298Z
¶ title: 2023_ST_TN_A02_CFRP_Rods
description: Link: https://rocket-team.epfl.ch/en/rocket_ss/structure/Nordend/2023_ST_TN_A02
published: true
date: 2023-12-01T02:40:41.805Z
tags:
editor: markdown
dateCreated: 2023-08-18T09:25:33.298Z
¶ CFRP Rods Technical Note
¶ 1. Introduction
Carbon Fiber Reinforced Polymer (CFRP) rods play a crucial role as an integral component of the internal structure. They serve as the "skeleton" of the rocket.
The CFRP Rods are cut from a homemade CFRP plate, which production procedure can be found here.
¶ 2. Reference Documents
| Ref | Description | Doc. ID | Issue |
|---|---|---|---|
| [G01] | Internal Structure | 2023_ST_TN_G02 | 2023 |
¶ 3. Definitions and Abbreviations
| --- | --- |
| CFRP | Carbon Fiber Reinforced Polymer |
| FoS | Factor of safety |
| FEM | Finite element method |
| ST | Structure |
| ERT | EPFL Rocket Team |
| EPFL | École Polytechnique Fédérale de Lausanne |
¶ 4. Design
¶ 4.1. Requirements
Engineering requirements :
- 2 M6 holes at each end for interfaces
- Unified clamping solution, positioning, thickness and width across the modules
- Different length depending on the module needs
- Easy access to the rocket's interior
¶ 4.2. Role and characteristics
- Strength-to-Weight Ratio : One of the most notable features of CFRP rods is their exceptional strength-to-weight ratio. They can withstand high mechanical loads and stresses while adding minimal weight to the overall structure.
- Customizability : CFRP rods can be designed and engineered to meet the specific requirements of the rocket's internal structure. Engineers can adjust the orientation and arrangement of the carbon fibers within the composite to optimize the material's mechanical properties for the intended application.
- Manufacturing Process : CFRP rods are manufactured through a multi-step process. It involves impregnating carbon fibers with a polymer resin, usually epoxy, to create a composite material. This material is then cured under controlled conditions to solidify the resin and form the desired shape. The manufacturing process can be tailored to achieve specific mechanical properties and dimensions.
- Cost and Complexity : While CFRP rods offer significant advantages, their manufacturing process can be complex and often requires specialized equipment. As a result, they may be more expensive to produce compared to traditional materials. However, the benefits in terms of weight savings and performance often outweigh the cost considerations in aerospace and other high-performance applications.
¶ 4.3 Material Properties
CFRP rods are characterized by their remarkable strength-to-weight ratio, corrosion resistance, and flexibility. These properties stem from the synergistic combination of carbon fibers' high tensile strength and stiffness with the polymer matrix's durability.
The following specs are from the CFRP used this year for the rods manufacturing
Exact carbon spec sheets can be found here
| Material | Density [t/mm3] | E1 [MPa] | E2 [MPa] | E3 [MPa] |
|---|---|---|---|---|
| Carbon UD | 1.6e-9 | 1.64e5 | 1.17e4 | |
| Carbon Woven | 1.57e-9 | 6.65e4 | 6.65e4 | 1.e4 |
| Material | Nu12 | Nu13 | Nu23 | G12 [MPa] | G13 [MPa] | G23[MPa] |
|---|---|---|---|---|---|---|
| Carbon UD | 0.316 | 5.5e3 | 5.5e3 | 5.5e3 | ||
| Carbon Woven | 0.05 | 0.35 | 0.35 | 5e3 | 4.5e3 | 4.5e3 |
| Material | Tensile stress, fiber direction [MPa] | Compressive stress, fiber direction [MPa] | Tensile stress, transverse direction [MPa] | Compressive stress, transverse direction [MPa] | Shear stress [MPa] |
|---|---|---|---|---|---|
| Carbon UD | 2720 | 1690 | 64 | 304 | 120 |
| Carbon Woven | 800 | 924 | 800 | 924 | 79 |
¶ 4.4. Layup
The rods are composed of 17 layers of UD Carbon, woven in the following order :
¶ 4.5. Part Variants
The CFRP Rods are present under different variants in Nordend's internal structure, only the length and hole positioning is variant-specific
| --- | --- |
| Common Dimensions |
| Width | 30 [mm] |
| Depth | 3.9 [mm]|
| --- | --- |
| Length | 500 [mm] |
| --- | --- |
| Length | 600 [mm] |
| --- | --- |
| Length | 330 [mm] |
