Preface

Welcome to Applied Mechanics.

This is the written material for the mechanics, solid mechanics, machine elements and mechatronics courses at the School of Engineering in Jönköping, and it is being written while those courses are themselves being rebuilt.

Two convictions run through it. The first is that mechanics in the computer age is modelling rather than calculation. We set a problem up symbolically so that the structure of the answer and the influence of each parameter are visible before any numbers are committed, let the machine carry the algebra and the arithmetic, and spend the effort that saves on the idealisations and on whether the result is believable at all. Vectors, matrices and differential equations are the working language, visualisation is treated as part of the analysis rather than as decoration, and Python appears in the first part and never leaves. The language and the libraries are taught in their own right on the companion site python.ju.se, the preparatory course in scientific programming, so the chapters here can lean on NumPy, SymPy and Matplotlib without stopping to explain them.

The second is that the parts our students analyse should be parts they have made. Nearly everything here is designed for 3D printing and printed in the workshop, loaded on test equipment built in the department, and assembled into things that move. Material data comes from the students’ own specimens rather than from a datasheet, which is slower, occasionally embarrassing, and worth it, because a number you measured yourself is one you can defend. The school teaches within the CDIO framework, in which students conceive, design, implement and operate real systems. This book is the analysis those projects are meant to rest on.

The book is unfinished and will be for some time yet. The introduction sets out how it is arranged, why 3D printing runs through all of it, and what we are trying to build.