Working Model 2D is a motion simulation package fronted by its own graphical editing environment. By defining connected systems formed from rigid bodies, motors and springs, and defining constraining forces and torques, the user can build mechanical systems whose dynamic performance can be investigated at the click of a button. The program accepts imported data from popular CAD packages in DXF format in addition to systems created within its own environment, and furthermore will accept inputs from other applications such as Excel and Matlab to add control inputs to the models. An embedded Basic‐like script language has access to the system’s database and features, and may be used to enhance the use of the system, for example creating batch processes, iterative simulations and even customise the environment via new dialogue boxes. It should be noted that there are limitations to the script facilities if not running on a PC platform.
In use, the editing environment is simple and intuitive to use ‐ elementary models can be constructed and run within minutes of loading the software for the first time. Object parameters can be edited in full, allowing access to fundamental physical properties such as density, coefficients of friction and elasticity. Running the simulation shows the motion of the mechanical systems constructed by the user, giving an instant qualitative appraisal of performance. For more detailed analysis a number of virtual metres can be associated with points of interest on the model, displaying measurable quantities in a number of alternate formats such as digital or bargraph. Vector quantities can be shown as coloured arrows at their point of influence for further qualitative evaluation, and there is a range of input devices for applying input conditions to the model by sliders and buttons. The aesthetic dimension is not ignored with a full drawing suite allowing change of line styles, colours and component patterns, and the editor will map an externally generated bitmap onto a component.
As an educational tool the system seems ideal for confirming the solution of simple analyses, and as a handy adjunct to the design process for mechanisms, the system has much to offer the reluctant design engineer. The limitations of the two dimensional workspace and simple models for the inclusion of air resistance and electrostatics are no real hindrance to the utility of the software, particularly when considering the price.
