When writing a book on this subject, it is difficult to decide what to leave out. The world of mechanical design engineering is very broad and covers a wide range of subjects. This book is specifically aimed at the student design engineer who has left full- or part-time academic studies and requires a handy reference handbook. Some of the titles may seem a little obscure, but in my experience, working in a wide range of industries from machine tools to aerospace, I have used these subjects regularly.
The chapters on beams and torsion are included for obvious reasons. Why a chapter on limits and fits? Some student engineers have difficulty in determining the correct type of fit to specify and select either a combination that is too loose or one that is expensive to attain. The chapter on lugs and shear pins is important in the design engineer’s armory, as you will meet this design feature time and time again.
It is quite surprising that some lug designs are either underor overdesigned and have failed with very expensive results. I have addressed issues with mechanical fasteners, more specifically bolts and screws. I have not discussed other forms of fasteners such as rivets, and so forth, because there was insufficient space to do the subject full justice. This may be left to future publications. Because thick-wall or compound cylinders are not the exclusive province of the hydraulic or pneumatic engineer and are used quite extensively in mechanical engineering as connection features, I felt the subject should be covered.
The chapter covering helical compression springs will be useful to the student engineer. I debated whether to include tension and torsion springs but decided against that for the time being. This may be included in future publications. The helical compression spring is the most commonly used spring, which justified coverage in its own chapter. I introduce the subject of analytical stress analysis using the Mohr’s circle.
It is surprising that there are so many student engineers who have only had a passing reference to the circle; it has been used by me extensively in my career, as it helps to explain quite complex stress issues. Two chapters are devoted to stress analysis covering both analytical and experimental analysis. Although the chapter on experimental stress analysis may be considered rudimentary, it will give the reader an introduction to the subject. Fatigue and fracture have become very important subjects in engineering.
At times, fatigue and fracture can produce a number of catastrophic failures, ranging from the early comet disasters to a number of bridges and walkways failing. In most cases, a premature failure due to fatigue can be attributed to design errors, and the design engineer must be on his guard when designing components that are subject to cyclic loading. The chapter on gear systems should be self-explanatory. Sooner or later, the engineer will be faced with a problem regarding gearing, and some of the examples shown will be of assistance. Finally, the chapter on cams and followers I consider important because the information here will be useful in a motion control problem; this will give the reader an insight into the issues associated with cams and followers.
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