3D Modeling & CAD for Motorsport: Facts About Forces
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Facts About Forces
03.34
| 00:00 | - How we design a component and how that component is used will affect the loads that are applied to it. |
| 00:05 | That's why it's a good idea to have an understanding of how these forces act and how they'll affect our components. |
| 00:11 | So in this module, we'll be covering the 5 fundamental forces. |
| 00:14 | Let's start with compression and tension. |
| 00:18 | An easy way to visualise these two forces is by looking at an engine's connecting rod. |
| 00:23 | During the compression stroke, the conrod is placed in compression because we have two opposing forces trying to squeeze it together. |
| 00:30 | The crankshaft is rotating and trying to push the conrod up, while the pressure in the cylinder is trying to push it down. |
| 00:36 | Now let's look at what happens during the exhaust stroke. |
| 00:39 | The piston and conrod are initially moving up and expelling exhaust gas from the cylinder. |
| 00:44 | But when the piston reaches the top of the stroke, the conrod is placed in tension because the two opposing forces are trying to stretch it apart. |
| 00:52 | The inertia of the piston wants to keep travelling up but the crankshaft is trying to pull the conrod back down. |
| 00:59 | Next, let's look at shear. |
| 01:01 | A simple example of a shear force would be a bolted joint between two plates. |
| 01:05 | If opposing forces are applied to each plate, then the bolt is placed in shear where the forces have the effect of trying to cut through or rip the bolt in two. |
| 01:15 | This is a really important concept to understand and we'll be diving into it in much more detail soon in a dedicated module. |
| 01:22 | Next we have a bending force. |
| 01:24 | This is where a load is applied for example into the middle of a beam. |
| 01:28 | We can visualise this by looking at a bookshelf that's supported at both ends. |
| 01:33 | If enough load is applied to the centre of the bookshelf, it'll bend. |
| 01:37 | When this happens, the top of the shelf is placed in compression while the underside is placed in tension. |
| 01:43 | If a sufficient load is applied to the centre of the bookshelf, it'll end up failing. |
| 01:48 | The last force we need to understand is torsion which is another way of describing a twisting force. |
| 01:55 | This is what happens to a fastener every time we use a torque wrench to tighten it. |
| 01:59 | We're applying torque to the head of the fastener which has the effect of twisting it. |
| 02:03 | The reason that we need to understand these forces is that components tend to be stronger when forces are applied in certain ways. |
| 02:12 | It's difficult to apply a blanket rule when designing for automotive purposes but it's generally safe to say that most materials can withstand the most stress and are the most reliable in compression and tension so we want to factor this into our design, doing our best to make sure that loads are applied purely in tension or compression wherever possible. |
| 02:33 | This is often achieved by using a triangle which is one of the strongest geometric shapes. |
| 02:37 | Let's look at what happens when a load is applied to one point in a triangle. |
| 02:42 | Here we can see that it's distributed down each side, applying a compressive force to these two members. |
| 02:49 | At the same time, the third side of the triangle is placed in tension. |
| 02:53 | This is why it's really common to see triangular shapes used in many areas of motorsport design. |
| 02:58 | For example, suspension wishbone, which in its simplest form is just a triangle. |
| 03:04 | Triangles are also incorporated into tube frame chassis designs and roll cages in order to add strength and rigidity. |
| 03:12 | The key point to take away from this module is that it's very important to properly understand the different types of forces that'll be applied to the components that we are designing in CAD software and how they can affect the component. |
| 03:25 | Have a good handle on this and you'll be well on your way to designing and building strong, stiff and safe parts. |
