Fundamental Design Principles

  • Research and analysis of existing solutions

Background research and study of the state-of-the-art technology related to the initiated project is an essential stage to be undertaken prior to the active phase of product design and development. You, as a designer, should study and review as many existing solutions available on the market as possible, if any.

  • Ergonomics

Ergonomics is a discipline dealing with the interactions among humans and other elements of a system; ergonomics is also the name of the profession that studies and implements design principles and methods to optimize human comfort and safety in aggregate with system performance.

  • Occam’s razor

In general, Occam's Razor states that the simplest explanation is usually true. For example, if your electronic appliance suddenly stopped working, first check the cable or the charge of the battery – a good chance is that the problem was there. In engineering, using Occam's Razor means to do something (design, test, analyze, model, etc.) in the simplest manner possible, and simpler is usually better.

  • Independent Functions. Keep the functions of a design independent from one another.

Independent functionality is the key factor in different engineering design domains. Independent functionality may lead to functional independence and decomposition. The goal of decomposition is to simplify the complex design problem in order to facilitate the decision-making process, to increase system reliability and, potentially, to save different types of resources.

  • Creativity and brainstorming

In engineering design, the goal is to create, design and build new product or system, while implementing new solution compared to the existing products available on the market. The most important stage in the design process, especially during conceptual design, is idea generation which is a very absorbing and demanding task.

Among a variety of different methods intended for removing mental blocks suppressing intellectual abilities, the brainstorming is the one most commonly used for the stimulation of creativity.

The brainstorming must follow few main principles, among them:

  1. All participants have equal roles, however one of the team members should bear an additional role of moderator.
  2. Only one conversation should be ensured at a time.
  3. The length of the brainstorm session should be about 20-30 minutes, during this time the team must generate as many ideas as possible.
  4. In the session, the team should stay focused on the topic.
  5. Any idea is a good idea, seemingly crazy ideas should be allowed to be expressed and people should be encouraged to generate all kind of novel ideas.
  • Lateral thinking

It is a mental process of generating ideas and solving problems not directly, with a frontal attack, but by evaluation of a situation and approaching problem from a non-standard direction.

Four principles of the lateral thinking process:

  1. recognize the dominant ideas that polarize perception of a problem,
  2. search for different ways of looking at things,
  3. relax the rigid control applied to the vertical thinking, and
  4. use chance to encourage other ideas. This last factor has to do with the fact that lateral thinking involves low-probability ideas which are unlikely to occur in the normal course of events.
  • Duality of innovation & design

In practice, design process possesses duality in its nature. On the one hand, design requires from you concentration on one problem only (this is what is formulated in the literature as “staring at one problem for extended period”). On the other hand, creative design calls for the broad outlook and open-minded approach.

  • Engineering design practice

Engineering design practicedepend on two major factors:

  1. Background, experience and preferences of the designer;
  2. Available technology, i.e., hardware and software, that can be used as a support for designer process.

Correspondingly, the most qualified and experienced design engineer, that uses the state-of-the-art computer technology, with high probability will produce a top-quality product.

  • Units and measurements

In general, engineers in the North America are burdened with two systems of units and measurements: the English or USCS (US Customary System) and the metric or SI (Système International d’Unités).

Therefore, understanding both unit systems is essential for the US and Canadian engineers’ activities, including design.

  • Fasteners & methods of attachments

Fasteners are the devices that mechanically join two or more objects together, and they are essential for the assemblies of most engineering products, as well as for the installation of various devices (e.g., machinery and robots in the production or testing facilities, furniture and appliances in homes and offices, etc.). Hundreds of standard fasteners are available on the market, but during product development engineers or designers can also use custom-made devices.

  • Off-the-shelf components in design

From the Occam’s razor we know that design should be as simple as possible. Instead of designing some components from the scratch, you can use standard elements available on the market. Therefore, while accomplishing a design project, a good practice is to find as many off-the-shelf parts and units for the product as possible.

  • Modular design

The principle of modular design allows end user to customize, repair and reuse products by simple replacement of a faulty component.

  • Freezes

In engineering design freezes mark the end points of various development stages.

At each stage the possibility of further engineering changes significantly decreases after development reaches corresponding freeze point.

  • Accuracy, repeatability, and resolution

Accuracy – indicates how close a measured value is to the real quantity of what is being measured. Accuracy cannot be defined without reference to an actual physical value of the object.

Repeatability – describes how well a system or device (e.g. a robotic end effector) can reproduce an outcome (position) in unchanged conditions.

Resolution – is the smallest variation the system can display, such as resolution of a screen or a picture, or measure, as it is in a coordinate measuring machine. In the industry, resolution is especially important in mechanical processing and surface finishing.

  • Sensitive directions

While designing it is important to estimate in what directions of the 3D part dimension accuracy is the most important. During assigning dimensions, you can use either parallel (baseline) or series (chain) dimensioning approaches. Parallel dimensioning is the one where all dimensions in one direction refer to the same origin which is called baseline, or datum. In the series dimensioning, dimension of a part feature in a series can refer to the end of the previous feature, until the very first dimension refers to the datum.

  • Reference features

In engineering drawing, a reference is a relation with the datum from which the measurements are made on the part. In engineering, datum is used for geometric dimensioning and tolerancing and it is a feature on an object (a point, a surface, a line, an axis, or a plane) used to create a reference system for measurements.

  • Managing friction

Any mechanical design that has moving parts will have friction. Whenever possible, you should avoid kinetic (sliding) friction.

The best way to avoid kinetic friction in rotary motion is to replace it with the rolling friction by means of rolling bearings.

  • Centers of Action

If forces are applied through the centers of mass, rigidity, and friction, there will be no moments and hence minimal errors. The entire structure has better balance and stability.

  • Preloads and press fits

If the fit between objects is loose, it is impossible to predict position of one object with respect to the other. To remove the slack in the system, it is recommended to apply load (preload) between the objects as part of manufacturing and assembly. Extreme type of load between two objects is press fit.




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