mechanical engineering systems design

Saturday, April 22, 2023 1

Mechanical Engineering Systems DesignEng. R. L. NkumbwaCopperbelt University, 2010Zambia

Saturday, April 22, 2023 Eng Nkumbwa @ CBU 2Saturday, April 22, 2023 2

Who is a ‘Mechanical Engineer’?

Mechanical Engineers are associated with the production and processing of energy and with providing the means of production, the tools of transportation and the techniques of automations.

(Shigley, 2004).


Mechanical Engineering Design

Mechanical Engineering Design involves all the disciplines of mechanical engineering including; mechanics of fluids and solids, manufacturing processes, mass and solids, momentum transfer and electrical and information technology theory.


Design Process Elements

To understand the total design process, answering the following questions may help us understand how design proceeds: How does it begin? Does the Engineer simply sit down at a desk with a

plunk sheet of paper and fold down some ideas? What happens next? What factors influence the decision making? How does the design process ends?

Saturday, April 22, 2023 Eng Nkumbwa @ CBU 5


Complete Design Process Phases

Recognition of Need

Presentation

Evaluation

Analysis & Optimisation

Problem Synthesis

Definition of Problem or Need


Design Process Example


Complete Design Process Phases

The process begins with recognition of a need and a decision to do something about it.

After many iteration, the process ends with the presentation of the plans for satisfying the need.

Depending on the nature of the design task, general design phases may be repeated through the life cycle of the product, from inception to termination.


Steps of the Design Process

Recognition and Identification: Sometimes but not always, design begins

when someone recognizes a need and decides to do something about it.

Recognition of a need and phrasing the need often constitute a highly creative act, because a need may be only a vague dissatisfaction, a feeling of uneasiness or a sensing that something is not right.



Definition of the Problem: This must include all the specifications for the

object that is to be designed. The specifications are the input and output

quantities, the characteristics and dimensions of the space the object must occupy and all the limitations on the quantities.

The specifications define the cost, the number to be manufactured, the expected life, the range, the operating temperature and the reliability.



Synthesis of a scheme connecting possible system elements is sometimes called the “Invention of the Concept”.

This is the first step in the synthesis task.



Research and Make Notes about:Analysis and OptimizationEvaluationPresentation


Design Considerations

Sometimes the strength required of an element in a system is an important factor in the determination of the geometry and the dimensions of the element.

In such a situation we say that strength is an important design consideration.


Design Considerations

When we say design consideration we are referring to some characteristics that influence the design of the element or perhaps the entire system.

Usually quite a number of such characteristics must be considered in a given design situation.


Important Design Considerations

Functionality Strength / Stress Distortion / Deflection / Stiffness Wear Corrosion Safety Reliability Manufacturability Utility Cost



Friction Weight Life Volume Liability Lubrication Noise Styling (Aesthetics) Shape



SizeControlThermal PropertiesSurfaceMarketabilityMaintenanceRe-Manufacturing / Resource RecoveryEnergy Consumption



Some of these factors have to do directly with the dimensions, the materials, the processing and the joining of the element of the system, and it should be noted that, throughout this design course, we will be giving attention to these factors.


Design Cost Profile


Design Changes & Time Used


Wrap-Up

How is Design Course - so far?Any feedback please…References as outlined in the Syllabus

mechanical engineering systems design

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