CADD for the Layman by K. Narayanan

* K. Narayanan is presently the CEO of STRUCT CADD SECTOR.

Introduction

Training on Computer Aided Design (CAD) applications is becoming as essential a requisite as the knowledge on the various underlying concepts of design which a student masters during his/her study curriculum.

Expertise on the design concepts alone, whatever be the domain of specialization and application, no longer helps the professional in arriving at a total solution for the design problem under focus. Though basic concepts and theories do play a vital role in framing the input data leading to an efficient design, it is the CAD software tool which ultimately provides the designer with an efficient and optimum design solution which involves carrying out multiple iterations together with fine tuning the input data. Most of the design solution mechanisms are so complex and tedious to perform that obtaining a complete solution by hand has become almost impossible.

With the increasingly available, affordable and truly powerful personal computers with very large data processing capacity, complicated design solutions are arrived at by putting these systems to use together with CAD software applications. Numerous CAD software packages, designed and developed to meet generic or highly specialized requirements of the design phases - from preliminary design to detailed three dimensional visualization - are becoming available more and more in the rapidly developing CAD application segment. The rate of awareness growth is, in fact, very high in India.

A number of design organizations across the world have already made their transition into computerization of the various design phases. The domains of application include the AEC (Architectural, Engineering & Construction) segment, Civil & Structural Engineering, Mechanical Engineering, Electrical & Electronics Engineering, and several other design disciplines.

CAD Flavours

Although the term "CAD" is used by one and all to mean its expansion "Computer Aided Design", the term "Design" is not understood well by many. The term "Design" can mean Visual Design which is governed by the aesthetics of the product or model, it can mean the Functional Design which is governed by the operational characteristics of the product or model, and it can mean the Strength Design which is governed by the material characteristics of the product or model. All these three components must be put together to obtain the total design solution of any product or model. Depending on the purpose of application, viz., Visual Design, Functional Design or Strength Design, the relevant CAD software must be put to use and such software applications are mostly developed to perform any one of the above operations only. Therefore, a complete CAD solution of a project at hand would mean the use of more than one CAD software tool for the different phases of the project.

Visual Design

Visual Design would involve developing a two or three dimensional view of the object or prototype with exterior or interior details. Multiple views of the same object is usually studied and additional cross sectional views are also sometimes drawn to assure its functionality for which it is designed. The visual design part is an inevitable part of any design problem and this always go hand in hand with the functional part. For instance, an Architectural plan of a residential building can be studied for its functionality only by putting the different parts of the building together. Here, the building plan which shows the location of the rooms and their connectivity to form a single functional system for living, can be easily visualized by transferring the ideas on paper and a variety of CAD software applications are available to serve this purpose.

Moreover, there can be more than one visual design for the same functional design. A good example is to consider a residential apartment with a living cum dining room, two bed rooms, a kitchen and a toilet. There can be another residential apartment which fully satisfies these functional requirements but having an entirely different appearance when looked from outside. The arrangement of the rooms may also differ even though the functionality is exactly the same.

Functional Design

Functional Design, which is the most important part among the three phases, would involve defining the required functions the model should perform. Functional Design influences the Visual Design to a great extent and sometimes the Visual Design is carried out in parallel with the Functional Design. In the above example, for the same functionality of a residential building, a number of visual designs are possible. This is possible by rearranging the components (the rooms) of the parent model (the building) without affecting the purpose.

Structural Design

Structural Design or Strength Design is always the final phase of design leading to implementation or manufacture of the model. This includes analyzing the model for the loads or pressure acting over the model and then studying the model behavior under these applied forces. The model behavior greatly depends on the type of material used, the sizes and shapes of the various components of the model, environmental factors, and so on. If the model is found to fail structurally, then, the sizes of those components which constitute the failure, are modified and the model is reanalyzed and redesigned to verify safety. Alternatively, the material strength of the model is increased without changing the sizes of components. Sometimes, minor changes in the visual design, without affecting the functionality, is also done so that the corresponding design is structurally safe.

Therefore, the Structural Design phase plays a substantial role in governing the cost of manufacturing the model. To minimize the cost of manufacturing, without altering the visual and functional design, Optimization techniques are also induced into the Structural Design phase thereby obtaining a safe solution with minimum quantity of material used. Such optimization techniques involve highly complex mathematical algorithms and are very difficult to perform without a suitable CAD software tool.

Example

Let us consider the example of a chair with four legs. Though the functional design is the same, which is to make the occupant of the chair comfortable, there can be hundreds of visual designs possible with the same type of material used for manufacturing the chair. Timber, Steel, Aluminium, Cane, etc., are some of the parent material used to make a chair and the strength characteristics of each of these material are totally different even though each material may fully satisfy the visual and functional aspects.

CAD tools available for Visual Design are vast and some of them are so powerful that a three dimensional model of the product (in this case, the chair) can be virtually constructed within the computer with all visual and material characteristics applied. Such models can be rendered photo-realistically and can even be viewed from different angles. This greatly helps the designer to locate flaws, if any, in the visual design and subsequently correct them. To exemplify, two residential apartments in the first example can be virtually constructed in the computer and each of these can be photo-realistically rendered and shown to the prospective customers. As tastes always differ, this display of alternatives in real-life colors and details, actually helps the prospective customer to select the alternative which he/she likes, in addition to recommending suggestions for minor improvements in the selected design.

Thus, CAD software tools play a very vital role in helping design several preliminary models quickly and then, select a suitable design from such generated alternatives. A detailed analysis and design can then be carried out on the selected model to arrive at the final solution for implementation.

Summary

These advantages have made more and more design organizations to switch over and take active part in the CAD revolution. The results are much encouraging and customers also prefer consulting CAD Solution Centres compared to conventional Design Centres. The customer also knows that he/she gets a better design from a CAD Solution Provider and any last minute modification made by him/her can be easily incorporated into the previous design to get a fully revised design, much faster. The CAD revolution has resulted in enormous man power requirements to operate on various CAD software tools. It is no more necessary to be an Engineer to use a generic CAD software tool for preparing functional layout and preliminary sketches of a model. With CAD supervisors appointed, most of the design organizations have even found Arts, Commerce and Science graduates very useful and productive in using generic CAD tools. This also greatly helps the jobless youth to obtain a CAD oriented working environment without much difficulty provided there is an inherent and genuine taste and talent in learning CAD. Overseas opportunities are also increasing day by day and there is acute shortage of CAD operators in the Asia Pacific, especially in Malaysia, Singapore, Hong Kong, Taiwan, Indonesia, Philippines and Bangkok.

Students who join CAD training courses must also make sure that the programme they are going to attend is Quality-oriented, cost-effective, fully practical- oriented with real-life design projects, and productive in terms of the type of CAD application to be trained on, meeting the requirements of the industry. It is always essential to make a comparative study before joining any CAD training centre to verify whether his/her requirements will be totally met by the training centre.