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The purpose of this research project is to investigate the effectiveness and viability of composite chassis components through the design and implementation of structural “sandwich” panels. These will be pursued for an increased strength-to-weight ratio as well as higher stiffness as compared to a conventional tubular frame.
Design Process
Sandwich Panel
To start, the design of the structural “sandwich” panel is achieved by utilizing two outer carbon fiber layers and inserting a core structure between them, typically with aluminum honeycomb, foam, or Nomex.
Each carbon fiber layer is created by using multiple carbon fiber lamina at different orientations to create a laminate, bonded together with epoxy resin. The orientation stacking of the carbon fiber lamina is to maximize material properties in multiple directions, in order to retain high stiffness and low deformation properties in a multitude of loading situations.
Additionally, the core material of the panel is utilized to effectively transfer loads across the entire of area of the carbon fiber panel, as well as resist shear loads and bending stresses across the carbon fiber. The material of the core structure is determined based upon the application.
In the case of a structural chassis panel, where thermal conductivity is a minimal issue and structural rigidity is the top concern, aluminum honeycomb seems to be the most applicable core material.
Need to look more into why aluminum as opposed to other core materials
This also means we need to understand all the dimensions associated with honeycomb, how that affects each material, what each material’s use case is
Essentially need to make a decision matrix for core material selection
Need to also dive further into carbon fiber
i.e. exam the differences between uni-directional, twill weave etc.
look into how laminae/ply stacking works (essentially what orientations should we utilize to make panels that work best for our application)
Need to also examine epoxies that work for this application
that means we need to consider if the epoxy will interface well with every material used in the sandwich panel, how long it takes to dry/cure, etc.
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Mounting Solutions
In terms of mounting components to the panels or even mounting the panels themselves to a tubular area of the car, there are various solutions to accommodate each specific application.
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A commonly used solution is using thru-bolts, which can end up leading to shear and moment in the core material or compression and bearing stress if an axial load is placed on it. This means that selecting a core material and evaluating the loads of each mounting joint go hand in hand together, as they can both directly affect the effectiveness of the joint and panel as a whole.
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Potted inserts are another viable mounting solution, which utilizes an insert that is placed in a cutout section of the core material and adhered to the panel by a potting adhesive, which constrains the insert in all six degrees of freedom.
Additionally, thru-bolts could be used in a different configuration, where a custom mounting bracket is created that bolts onto the panel, and any moving part/anything experiencing load is mounted to the bracket, and not directly onto the panel.
need to examine each one of these mounting capabilities
Strengths, weaknesses, ease of manufacturing, cost, etc.
Decision matrix
Manufacturing Process
To manufacture the… blah blah blah
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later tonight
Testing Methodology
In order to test the viability and capabilities of the structural composite panels, both empirical testing and FEA simulation shall be utilized.
To start, materials testing, which includes tensile, 3-point bend, shear, and compression testing, shall be employed to understand the material properties of the composite paneling, as well as ensure the panels are viable at least in the early stage to continue research, in pursuit of a fully composite panel chassis. Each material test will result in critical numerical data, such as yield and ultimate strength, elastic modulus, as well as fracture toughness and flexural modulus. Each one of these data points can then be used to characterize the composite material as a whole. Additionally, this data can be used in hand calculations or brought into a Finite Element Analysis program such as ANSYS, to then predict and understand how the material, based on its properties, will react in situations relevant to the ASC and FSGP competitions.
In terms of FEA testing, ANSYS, utilizing its ACP program, can accurately represent the composite structure in junction with the data collected from the empirical testing, which allows us to simulate the entire chassis structure as one piece, helping us account for the complex geometry of the chassis and load cases of the ASC regulations, which would be hard to replicate in an empirical testing setup.
need to go into specifics on how each empirical test will be conducted to get accurate results
Also explain how each material property will be extracted/calculated given the test results
need to explain a little bit more about how ANSYS/FEA testing works as it pertains to a composite structure
I (noah) can fill in this section but we need to essentially explain the features of pre-ACP and post-ACP on ANSYS, how they reflect the IRL sandwich panels in a simulation setting, and how we plan on using it to prove to ASC that our panels actually pass regs