Polytechnic 4th Semester (ME 40052) | Mechanical Engineering
Introduction to Computer-Aided Design (CAD)
Computer-Aided Design (CAD) is a technology used to create, modify, analyze, and optimize designs using computer software. It enhances the efficiency, accuracy, and flexibility of the design process. CAD is widely used in engineering, architecture, product design, and manufacturing.
Example:
A car company uses CAD software to design a new vehicle model. The software helps in creating detailed 3D models, performing stress analysis, and generating technical drawings for manufacturing.
CAD Hardware and Software
1. CAD Hardware
To run CAD software efficiently, certain hardware components are required:
✔ High-performance Computer (Workstation): Used for processing complex designs and simulations.
✔ Graphics Processing Unit (GPU): Required for rendering 3D models and real-time visualization.
✔ Input Devices:
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Mouse & Keyboard: For basic operations.
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Graphics Tablet: For hand-drawn sketches and annotations.
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3D Scanner: Converts physical models into digital CAD models.
✔ Output Devices: -
Monitor: High-resolution screens for better visualization.
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Plotters & Printers: For printing technical drawings and blueprints.
2. CAD Software
CAD software helps in creating 2D and 3D designs with precise measurements and engineering data.
✔ Popular CAD Software:
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AutoCAD – Used for 2D drafting and 3D modeling.
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SolidWorks – Used for mechanical product design.
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CATIA – Used in aerospace and automobile industries.
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Fusion 360 – Cloud-based CAD for 3D modeling.
✔ Types of CAD Software:
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2D CAD: Used for making technical drawings and schematics.
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3D CAD: Used for creating realistic 3D models with textures and simulations.
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Cloud-based CAD: Allows multiple engineers to work on the same design from different locations.
Product Modelling in CAD
Product modeling is the process of creating a virtual representation of a product in a CAD system. It includes:
✔ Wireframe Models: Shows the basic structure of a design using lines and curves.
✔ Surface Models: Creates smooth surfaces without showing internal features.
✔ Solid Models: Fully defined 3D models with volume, mass, and material properties.
✔ Parametric Models: Can be modified easily by changing design parameters.
Example:
A mobile phone design is first created as a wireframe model, then converted into a solid model with materials and textures, and finally tested for strength and durability.
Automatic Drafting in CAD
Drafting is the process of creating detailed technical drawings required for manufacturing. In the past, engineers used manual drawing boards, but CAD now allows for automatic drafting, which saves time and improves accuracy.
✔ Features of Automatic Drafting:
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Dimensioning: Automatic measurement labels for components.
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Annotations: Adding text descriptions and symbols.
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Standardization: Uses predefined templates and symbols.
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Layering: Organizing different parts of a drawing into separate layers.
✔ Example:
A machine component drawing with multiple views (front, top, side) is automatically generated in CAD software.
Engineering Analysis in CAD
CAD software is not only used for designing but also for analyzing a product's performance before manufacturing.
✔ Types of Engineering Analysis in CAD:
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Structural Analysis: Checks the strength and durability of a design.
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Thermal Analysis: Tests how heat will affect a component.
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Fluid Flow Analysis: Simulates airflow, water movement, and cooling systems.
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Motion Analysis: Tests how mechanical parts will move and function together.
✔ Example:
A bridge design is tested in CAD software for stress and wind resistance before construction.
Finite Element Method (FEM) in CAD
The Finite Element Method (FEM) is used in CAD to break down complex structures into small elements and analyze their behavior under different conditions.
✔ Steps in FEM:
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Preprocessing: Creating a 3D model and defining materials.
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Meshing: Dividing the model into smaller finite elements.
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Simulation: Applying forces, temperature, or pressure to test performance.
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Postprocessing: Analyzing results to improve the design.
✔ Example:
A car chassis is tested in FEM software to ensure it can withstand road impacts without breaking.
Design Review and Evaluation in CAD
Once a product is designed, it must be reviewed and evaluated for errors, cost efficiency, and performance.
✔ Design Review Process:
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Checking for errors or missing details.
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Comparing the design with industry standards.
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Evaluating material selection and cost-effectiveness.
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Testing design changes and optimizing for production.
✔ Example:
An aircraft wing design is reviewed for aerodynamics and structural strength before final approval.
Group Technology (GT) Centre in CAD
Group Technology (GT) is a concept where similar parts are grouped together to improve manufacturing efficiency.
✔ Features of Group Technology in CAD:
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Parts are classified based on shape, size, and function.
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Reduces duplication of designs.
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Improves standardization and automation.
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Saves time by using predefined templates.
✔ Example:
In an automobile factory, similar engine components are designed using standard templates to reduce errors and speed up production.
Conclusion
Computer-Aided Design (CAD) is an essential tool in modern manufacturing that improves design efficiency, accuracy, and cost-effectiveness. It allows engineers to create, analyze, and modify products in a virtual environment before actual production. With the integration of FEM, automatic drafting, and engineering analysis, CAD has become a vital part of modern mechanical engineering and manufacturing industries.
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