Motorsport Composite Fundamentals: Introduction

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Introduction

07.16

00:00	In this section of the course we're going to discuss the main composites used in automotive components.
00:05	These composites can be used in nearly all areas of a vehicle.
00:09	Exterior body panels and aero components, interior parts like dashboards and bucket seats, engine intakes or even highly stressed components like suspension arms and wheels.
00:21	There are a range of different composite materials and within these categories there's even more variation in how they're constructed, all of their own advantages and considerations.
00:31	But before we get into all of that we first need to understand what composite materials are and why we use them.
00:37	A composite consists of two or more materials which tend to have very different chemical and physical properties.
00:44	The result is a material with properties which surpass that of its individual elements to create something better for a certain application.
00:51	For example improve the stiffness although usually at the compromise of extra expense.
00:57	Composites shouldn't be mistaken for mixtures or solutions though as the individual elements remain separate and distinct rather than blending together.
01:06	Most commonly this involves a solid material reinforcement, commonly called the dispersed phase which is suspended in the matrix or continuous phase.
01:16	This matrix will be in liquid form during construction and then cure into a solid.
01:20	A typical example of this would be reinforced concrete where the reinforcement could be steel bars which are held in a matrix of cement.
01:29	Concrete is inexpensive and extremely strong in compression which is like trying to squeeze an object.
01:35	However, if loaded in tension or stretched in other words, it'll quickly break apart.
01:40	These steel bars and reinforced concrete composite resist tension and improve this property.
01:46	Composites come in many different forms, some using powders to reinforce the matrix.
01:51	However, in high performance applications like aerospace, yachts, bicycles or in our case motorsport, fibre reinforced polymers also referred to as fibre reinforced plastics are by far the most widely used and have the most ideal properties and therefore will be our focus in this course.
02:09	A quick note here, FRP stands for fibre reinforced polymer but it's also commonly used as shorthand for fibre glass reinforced polymer or plastic as well.
02:21	So, we just need to be aware of what's being discussed.
02:24	For our discussions we just need to understand that a polymer is a large molecule made up of a long chain of identical molecules and plastics are made up of polymers.
02:35	Regardless, for these composites, the reinforcing fibre is a solid material drawn out into a very thin thread or filament which is straight.
02:43	Although due to how thin it is, it can usually be bent very easily.
02:48	The polymer matrix is typically resin which is in a highly viscous liquid state during construction but cures into a solid.
02:55	Epoxy resins tend to be the gold standard for ultimate high performance in composites and top tier motorsport due to how they bond to the reinforcement.
03:05	With that said, polyester and vinylester resins also have their uses and are well suited to the type of work that we'll be doing in this fundamentals course.
03:13	Something to note though is that all the composites we'll discuss degrade as a result of exposure to UV light from the sun.
03:21	And this is mostly a result of the resin, not the reinforcement.
03:24	The outcome is discolouring of the composite and the matrix becoming brittle or even cracking or crumbling.
03:31	So, just keep in mind that this can be the case for all our composites although some resins are worse than others here.
03:38	Additives and finishes can be used to prevent this issue but we'll come back to discuss all of this in more detail later in the course.
03:45	While this isn't an engineering course, we must understand a few concepts moving forward.
03:50	Stress and strain are two of the most important concepts in material science and engineering.
03:56	Stress is defined as the force per unit area that acts on a material, developing inside the material when it is subject to load.
04:05	Strain describes the deformation of the material as a result of that load.
04:09	With help from this plot we can see that the stress and strain increase in a linear relationship as the material is loaded.
04:16	The stress and strain build up as the material deforms elastically, meaning that if the load was released, the material would return to its original form, so it's temporary deformation.
04:28	This occurs up until the yield point, which is where permanent deformation will begin and past this, the material won't return to its original form.
04:36	The increase in stress past this point will be less than the increase in strain.
04:41	This will continue until the material fractures or breaks.
04:45	Something that fails at a relatively low strain is described as brittle, whereas one that takes a lot of strain is ductile.
04:52	The area under the curve describes how tough the material is, in other words, how much energy it takes to break the material.
05:00	For motorsport composites, we generally are only interested in the elastic area of temporary deformation, and the two main properties here are strength and stiffness.
05:10	The strength of the material is how much stress it can take and recover from before it yields, while the stiffness is the resistance to deformation, which is the slope of the linear line from the plot.
05:22	In other words, a stiffer material will take more stress with less strain.
05:28	It's important to understand that strength and stiffness are not the same.
05:32	You can have a material that's very strong and not stiff, and vice versa.
05:37	Or of course, a material could be both strong and stiff.
05:40	The other property that's important to us is density, which describes the mass of the material per unit volume.
05:47	In other words, how much a certain amount of the material weighs.
05:51	FRPs are the go-to composites for motorsports due to their great strength to weight ratio.
05:56	This basically means they can be lightweight while still providing enough strength for the harsh loading conditions.
06:04	In saying that, the common FRPs used in motorsport, like fiberglass, carbon fiber and Kevlar, all have varying strengths, stiffnesses and density, as well as other properties like resistance to heat and more.
06:18	However, cost is usually a primary practical limitation.
06:21	This cost isn't so much about the raw materials themselves, in fact it's all relatively cheap, but more a result of the manufacturing process and the expertise and time these require.
06:33	Composite construction doesn't lend itself so easily to automation, meaning most of the parts will require some amount of human work, the techniques of which we'll also be covering later in this course.
06:44	With that covered, let's quickly go back over the key points to take away from this introductory module.
06:50	Composites are made up of multiple materials, typically a reinforcement material within a matrix, with the purpose of achieving an advantage over the individual elements.
07:00	In motorsport we mostly use fiber reinforced polymers, commonly referred to as FRP composites, like fiberglass, carbon fiber and Kevlar, as they offer great strength at a low weight.