 Hello everyone, myself Professor Prithish Chittay, working as an assistant professor in mechanical engineering department, Valchian Institute of Technology, Solapur. Now, this will be our fourth session. In this fourth session, we will discuss geometrical modeling. In our last sessions, we have discussed the geometrical transformation, their numericals and the concatenation method. Now, what are the learning outcomes? The students will be able to explain the different types of geometrical modeling, like the wireframe, surface and the solid modeling. Also, they can describe the different schemes of solid modeling, like constructive solid geometry, CHG and boundary representations, that is B representations. These are the contents. First, we will discuss the geometrical modeling, after that we will discuss the different types of geometrical modeling, and after that we will discuss the different schemes based on the solid model. What is meant by geometrical modeling? First we will see what is meant by model. A model is mathematical representation of different geometrical entities, where we have to store these geometrical entities in the computer memory. In earlier days, it is really difficult to represent these models manually, it will take a very much time. But with the help of these different modeling softwares like the Katia, Unigraphics or the Solidworks, we can say that there is a time saving and the accuracy is more. So geometrical modeling, what is meant by geometrical modeling? This is the computer representation of any geometrical entity of mechanical component with the help of different geometrical softwares, which is called geometrical modeling. So where we can use the geometrical modeling? For the 3D modeling or maybe the 2D modeling, before 3D modeling we have to use the 2D sketches. In the Katia we have to use the 2D sketches. After that we can provide a third dimension that is called as 3D modeling or which is also called as part designing. And after combining each and every component that is 3D component, we can provide the assembly. Also we can provide the computer added drafting. Computer added drafting means providing the front view, top view and side view and the isometric view with the help of the part list which is very important or we can call it as the build of material and which is automatic in the different modeling softwares. Manually if you are doing this drafting part which is very difficult, right? So accuracy is also very more the efficient. So we can use the computer added drafting only by clicking on the one icon or the tool we can get the maybe the front view or maybe the top view or maybe the sectional side view maybe the right hand side view or maybe the left hand side view. And also we can create the build of material. This is one simple example. This is a pipe, a 3D pipe also with the help of we are having these sections here. So we can create these types of mechanical components in the different modeling softwares like Katia. Also we can provide the different types of analysis like the kinematic analysis, the structural analysis or maybe the static or the dynamic analysis, vibrational analysis, thermal analysis. These are the different types of analysis. There are different types of analysis softwares like maybe the ANSYS hyper words after that idea, NASTRON, LSDANA these are the different analysis software. We can do the analysis in the different modeling softwares like the solid words or maybe the Katia. But these analysis softwares is having the very efficient and the modeling softwares. But before analysis we have to mesh the different components to get the discretization that is to create the nodes and the elements. For the different meshing there are the different, suppose you want to create the meshing for the different components. Suppose you want to provide the meshing on this pipe or the elbow, here you can provide the meshing with the help of different softwares like the hyper mesh or also ANSYS also you can provide the meshing. The types of geometrical modeling, as we have discussed there are the three types of geometrical modeling, wire frame modeling, surface modeling and the solid modeling. First we will discuss the wire frame modeling. So these are the some examples of the wire frame modeling. Wire frame modeling is the very least important geometrical modeling. For example application the toolpath simulation. In the CNC programming there is a toolpath simulation you can provide the wire frame modeling there. But also the advantage is that it will take very less memory to save that particular component or the wire frame model into the computer memory than the surface model and the solid model. It consists of, you can see the different edges or maybe the points, maybe the XYZ points and the edges. It doesn't consist of any skin or the surface or maybe the mass and the volume. It doesn't consist of any skin or the surface or the mass and the volume. Because you want to calculate these properties you can't calculate in the wire frame modeling. So only the advantage is you can save this file very easily with the help of very less memory and also wire frame modeling is not using for the any modeling. So we are using the surface modeling and the solid modeling for the particular applications. So these are the some examples. Surface modeling. Surface modeling is the second type of the geometrical modeling which is very important applications in the aerospace after that the turbine blades right. After that the submarine gearboxes here for example this bonnet of the particular four wheeler. Suppose you want to model this we have to use the surface model. What it consists of? It consists of the edges and the points after that it consists of the skin or the surface after that it consists of the mass but it doesn't consist of the volume only it doesn't consist of the volume the volume will be there in the solid model. The thickness is very less here you can see this is the we can call as the condition or the requirement from the customer that we we doesn't want any thickness or very less thickness in the particular model for the bonnet it is it is required to be very less thickness. So suppose you want to create the bonnet model we have to use the surface modeling. So this is the surface modeling. We can provide any analysis the types of analysis suppose you want to calculate the different properties like the mass volume or the stress on the stress strain after that the one message stresses you can calculate in the surface modeling because it consists of the mass after that different types of surface modeling. The plane surface very simple which will be moving in the only one direction here after that the second one will be over the ruled surface which is moving to the two direction that is boundary one and boundary two. So as per this curve there will be the creation of the modeling here only this one here after that the edge surface the four boundaries will be there. So this one this will be one boundary this will be our curvature as per the requirement and the second one that will be only the linear part. So we want the two suppose the surfaces so you can provide the edge surface. Now the fourth type is tabulated surface suppose you want the combination of the curvature and the linear surface only provide this curvature and the linear surface you can get this a particular a planar and the curvature surfaces here. Solid model. Solid model consists of everything this is the most important type of geometrical modeling and which will be used for the different applications for the mechanical components. For example this is the application of the blower suppose you want to create the model of the any machine you can use the solid modeling right this is one example solid model consists of the different edges points after that the surface after that the thickness you can create or you can calculate the different properties or the parameters like the mass volume it consists of the volume you can calculate the stress strain and the one message stress deformation you can calculate with the help of different analysis software. So the solid modeling is very important suppose you want to calculate the suppose you want to develop any solid model you can create any solid model in the cut here or maybe the solid words with the help of different the tools or the accounts like the pad pocket example or maybe the shaft let's think about this equation or maybe the question how to distinguish between the surface and the solid model think about this now what are the different schemes of solid model the first scheme is constructive solid geometry here constructive solid geometry can provide the different Boolean operations for example here we are adding the two materials first one will be the rectangle and another material is the here the circular rectangular component and the circular component we are providing the union scheme or the union bound the Boolean operation that is a plus b after that here we are subtracting the one component from the another component that is a minus b here we are subtracting the another component from the first component that is b minus a after that this will be the intersection the intersection means the similar part which is present inside the first and second component which will be there as a union part the boundary representation the constructive solid geometry is also called as the C representation the boundary representation is called as B representation the boundary representation provide you each and every views for example maybe the front view the top view the left hand side view the right hand side view also you can get the isometric view right a part by part view you can get it with the help of the boundary representation boundary the boundary itself which called as the front view top view side view maybe the left hand side view or with the right hand side view isometric view you can get it inside that right so bound and which is very easily we can done with the help of the computer added drafting these are the references thank you