Module 2

Conceptual Design
Conceptual Design is an early phase of the design process, in which the broad outlines of
function and form of something are articulated. It includes the design of interactions,
experiences, processes and strategies. It involves an understanding of people's needs - and
how to meet them with products, services, & processes. Common artefacts of conceptual
design are concept sketches and models.
It is a process in which we initiate the design and come up with a number of design concepts
and then narrow down to the single best concept. This involved the following steps.

 Identification of customer needs: The mail objective of this is to completely

understand the customers’ needs and to communicate them to the design team
 Problem definition: The mail goal of this activity is to create a statement that describes
what all needs to be accomplished to meet the needs of the customers’ requirements.
 Gathering Information: In this step, we collect all the information that can be helpful
for developing and translating the customers’ needs into engineering design.
 Conceptualization: In this step, broad sets of concepts are generated that can
potentially satisfy the problem statement
 Concept selection: The main objective of this step is to evaluate the various design
concepts, modifying and evolving into a single preferred concept.

Generation, Selection & Embodiment of Concept

Concept generation and the final selection of a concept through proper evaluation are critical
decision making steps in product development. The primary aim of concept generation and
evaluation is to ensure that the product can perform all of the major functions. This may be
done by simple calculations, sketches, circuit diagram, proof-of-concept models, or by a
detailed written description of the concept. The stage of concept generation and evaluation
should minimize the possibility of misrepresenting a solution, which may actually be effective,
and consider different ramification of a final decision. For example, not considering the
customer’s need during the concept generation and evaluation phase may lead to the failure
of the product in the market.
Typical steps involved in concept generation and evaluation is shown below.

Creative thinking is critical for concept generation for a product development. The process of
creative thinking can be viewed as a step to move from an unstructured idea to a well-
structured, from an implicit to an explicit design.
Conceptual Decomposition
An effective way to solve a complex problem is to decompose it into smaller parts that are
easier to manage and then recombine all the ideas or designs to arrive at the final solution.
There are two main approaches towards conceptual decomposition.
Decomposition in Physical Domain

Decomposition of a bicycle in physical domain for product design purpose

Decomposition in Function Domain
In functional decomposition, the system functions are descried as the transformation
between an initial stage and the desired final state. The process of functional decomposition
describes the design problem in terms of flow of energy, material and information.
Generating Design Concepts
The design concepts are necessary to build the functions of the product. In other words, the
design concepts provide the answer “how” for the intended function of a product. Usually, a
design team is formed in which every team member spends several hours working individually
on a few subsets of the overall problem for example, how to identify the sub-functions, and
so on, Next, the team members would assemble together to discuss and improve the concepts
developed individually and in turn, a number of small design concepts would be generated.
Morphological Chart
The morphological chart is a method to arrange all the functions and sub-functions in a logical
order. The morphological chart also enlists the possible “how”s for each sub-functions with
an aim to realize the combinations of ideas comprising several design concepts. Following is
the typical procedure to develop a morphological chart.

 Establish the functions that the design product must perform

 List the functions, one per row, in a chart.
 For each function (row), list a wide range of sub-solutions, one per column.
 Select an acceptable set of sub-solutions, one for each function.
Table shows an example of a morphological chart for the packing of parts like nuts and screws,
etc. In the chart, some of the alternatives along a row may be combined to give a single
solution, e.g. for picking up the parts, a vacuum arm could be used and for orienting parts,
step feeder can be used. If every solution on each row is compatible with all the solutions on
the other rows the number of the possible solutions to the system is a multiple of all the ideas
on the rows, the possibilities would be enormous.
Embodiment Design
The embodiment design phase will take the abstract design concept and mold it into a system
that can actually be produced. Most of the activities in this phase are devoted to finalizing the
product architecture, determining the shape and form of the parts that will satisfy the
required function, and quantifying the important design parameters. The decisions during this
phase should be as much as possible be justified by mathematical and physical proof or
validation. Embodiment design is briefly classified into three sections.

 Product Architecture that involves arranging physical elements to carry out functions.
 Configuration Design that provides preliminary selection of materials and
manufacturing process and modelling or sizing of parts.
 Parametric Design that involves applying the concept and principles of design for
manufacturing to finalize the dimensions and the tolerances.

Product Architecture
Product architecture design is the stage when the arrangement of the physical components
of a product is realized to enable the product to carry out its required function. The basic
layout and the architecture of the product is established by defining the basic building blocks
of the product in terms of the function of these building blocks and the nature of their
interfaces. These basic building blocks are also known as chunks. Each chunk is made up of a
collection of components that would carry out a specified function. Thus the architecture of
the product is given by the relationships among the components in the product and the
functions that the product is being made to perform as a whole. There are two different styles
of product architecture. One is the modular architecture and the other is the integral
architecture. In the case of modular architecture, the building blocks implement only one or
a few intended functions and the interactions between two building blocks are well defined.
In the case of integral architecture, the implementation of a function is carried out by only
one or few building blocks often leading to poorly defined interactions between the building
blocks. Usually, a typical product architecture contains a combination of both the modular
and the integral architecture.

Schematic presentation of a modular architecture

Schematic presentation of a complex modular architecture

Failure mode and Effects Analysis (FMEA)

By performing FMEA we can determine all possible ways by which the components can
possibly fail in service and establish the effects of the failure on the system thus improving
the performance and quality of the product.
Design for Reliability
By designing for reliability the capacity for the product to operate without failure in the
service environment increases.
Robust Design
By performing the process of robust design high quality in product can be assured as it
reduces the variability in performance and manufacture over a wide range of operating
conditions. The following are typical steps undertaken towards the approach for robust
design.

 System design: This relates to what we have referred to as the product architecture
where the engineering principles are used to determine the basic configuration of the
system.
 Parametric design: Statistical methods and techniques are used to set nominal values
for the design variables that minimize the variability from uncontrollable variables in
the environment.
 Tolerance design: Extensive statistical methods are used to set the widest required
tolerance s on the design variables without increasing their variability.
Tolerance
Permissible tolerances must be placed on dimensions of a part to limit the acceptable
variations in the size of a part. A small tolerance means greater ease of interchangeability of
parts and less play or vibration but this obviously leads to increased cost in manufacturing.
Dimensions are used to specify the size and locations of the features. Tolerances determine
the acceptable variations to the ideal or nominal dimensions.

Taguchi Designs & DOE (Design of experiments)

A Taguchi design is a designed experiment that lets you choose a product or process that
functions more consistently in the operating environment. Taguchi designs recognize that not
all factors that cause variability can be controlled. These uncontrollable factors are called
noise factors. Taguchi designs try to identify controllable factors (control factors) that
minimize the effect of the noise factors. During experimentation, you manipulate noise
factors to force variability to occur and then determine optimal control factor settings that
make the process or product robust, or resistant to variation from the noise factors. A process
designed with this goal will produce more consistent output. A product designed with this
goal will deliver more consistent performance regardless of the environment in which it is
used.
A well-known example of Taguchi designs is from the Ina Tile Company of Japan in the 1950s.
The company was manufacturing too many tiles outside specified dimensions. A quality team
discovered that the temperature in the kiln used to bake the tiles varied, causing nonuniform
tile dimension. They could not eliminate the temperature variation because building a new
kiln was too costly. Thus, temperature was a noise factor. Using Taguchi designed
experiments, the team found that by increasing the clay's lime content, a control factor, the
tiles became more resistant, or robust, to the temperature variation in the kiln, letting them
manufacture more uniform tiles.
Taguchi designs use orthogonal arrays, which estimate the effects of factors on the response
mean and variation. An orthogonal array means the design is balanced so that factor levels
are weighted equally. Because of this, each factor can be assessed independently of all the
other factors, so the effect of one factor does not affect the estimation of a different factor.
This can reduce the time and cost associated with the experiment when fractionated designs
are used.

Design Optimisation
Design optimization is an engineering design methodology using a mathematical formulation
of a design problem to support selection of the optimal design among many alternatives.
Design optimization involves the following stages:

 Variables: Describe the design alternatives

 Objective: Elected functional combination of variables (to be maximized or minimized)
 Constraints: Combination of Variables expressed as equalities or inequalities that
must be satisfied for any acceptable design alternative
 Feasibility: Values for set of variables that satisfies all constraints and
minimizes/maximizes Objective.