Interaction Models for 2D Finite Element Modelling on Touch Devices

The computational power of hand held devices have increased significantly during the last years. Today it is possible to run advanced finite element simulations on these devices. This opens up new possibilities for creating software for the early design stage and for educational purposes. Touch devices such as the iPad has become increasingly popular, and the number of users are growing every day. The multi-touch interface of the iPad has changed the interaction between computer and human. Some of the precision of using a mouse is lost, but is replaced by a more direct interaction with objects on the screen. The direct manipulation is what makes the multi-touch interface well suited for structural mechanics problems. The ability to give the user a feeling of being able to directly manipulate a model. The aim of this thesis is to develop an application to investigate how to take advantage of the new possibilities that the multi-touch interfaces creates in the field of structural mechanics. There are today on the market some available software tools for the early stage design process, but they are mostly PC software. To investigate how the multi-touch interface can be used for this type of applications an iPad application has been developed. The iPad application has been developed using Objective C and C++, where C++ is used for the FE computations for performance reasons. The developed application is a finite element application using beam elements. A geometry can quickly be modeled using developed direct manipulation methods. The application does not have the conventional user interface, instead the result is continuously recomputed once the model is stable. Which is determined using an eigenvalue analysis. The developed application is avalible in App Store under the name "Sketch a Frame". The created application uses the advantages of the multi touch interface. Creating new methods for the modeling process which has enabled the user to get a feeling of direct manipulation.