Intro to Mechanisms

CMU’s Introduction to Mechanisms

Yi Zhang, Susan Finger and Stephannie Behrens have prepared an on-line introduction to mechanisms consisting of eight chapters and almost 100 figures. Access it at the link:

Four-bar linkage analysis: Slider-crank

The slider-crank is an important mechanism with a wide range of applications. Here are my notes on its kinematic analysis.

Slider-crank analysis

Slider-crank analysis

Four-bar linkage analysis

Four-bar linkage analysis: 4R quadrilateral

The four-bar linkage is a basic machine component. It comes in two primary forms the 4R quadridlateral and the slider-crank. Here are my notes for the analysis of the 4R quadrilateral.

Four-bar linkage analysis

Four-bar linkage analysis

DC motor torque and power

A copy of my notes on DC motor torque and power can be downloaded at the link:

Motor Torque and Power

Motor Torque and Power

DC motor basics

The basic principles of DC motors are presented by Joe Wolfe of the University of New South Wales (Sydney, Australia) at the link:

Phyclips from UNSW

Phyclips from UNSW

Northwestern University (Chicago, Illinois) presents the basics of a DC motor in the Wiki page:

Northwestern University Wiki page

Northwestern University Wiki page

Mechanical Properties of Steel

The MatWeb site provides detailed information about materials such as the tensile strength of various compositions of steel.

MatWeb:  Material Property Data

MatWeb: Material Property Data

For example the search “low carbon steel” results in the list of links to information:

Total Materia

Unified Numbering System for Materials

There are a variety of numbering systems for materials such as steel. The unified numbering system (UNS) uses a letter to designate a material category followed by five numbers constructed from the existing materials designations to coordinate all of these numbering systems.

The unified numbering system (UNS) is described in Wikipedia at the link: Unified numbering system

Some of the category letters for steel are:
– G for AISI/SAE carbon and alloy steels;
– S for stainless steels; and
– T for tool steels.

Generally, the standard designation is inserted after the letter defining the material category. For example, AISI/SAE 1018 carbon steel has the UNS designation G10180.

The AISI-SAE steel alloy designation system is listed in Total Materia.
Also see Wikipedia at the link:  SAE steel grades

Koenigsegg Door

Koenigsegg door system

The doors of the Koenigsegg CCX open using the “dihedral synchro-helix door actuation” system. You can see this movement on the video

Material Properties Charts

Cambridge University provides a useful overview of materials properties such as the chart below.

Elastic Modulus v. Density

Elastic Modulus v. Density

The tutorial can be accessed at the link:

Jansen and Klann Legs

Comparison of Klann and Jansen leg linkages

Joseph Klann provides a useful comparison of the leg designs for his Mondo Spider and Theo Jansen’s Strandbeest at the link:

This link may be unreliable so here is an interesting article comparing the leg designs:  Mechanical Spider Using Klann Mechanism

This is a youtube video prepared by William Thielicke that illustrates the two leg mechanisms.