Book Description

Abstract: Bonded composite-metal assemblies present an interesting challenge to fixturing technology as it exists in its current form. Fixturing such an assembly has not yet been studied in depth. In particular, the aerospace industry, a common consumer of such technology, requires rethinking of the current status quo in design for assembly and fixturing techniques to improve accuracy, reduce assembly time and reduce fixturing and part assembly cost. This is especially true for the assembly of Unmanned Aerial Vehicles, or UAVs, which make use of this technology. In this thesis, several key technologies are investigated which have the potential to improve fixturing of composite-bonded assemblies. Kinematic constraint and fixturing serve to improve the accuracy of alignment by reducing the degree to which parts are overconstrained. This results in less induced stress and less potential for misalignment of parts in the fixture. Software that has been developed by Bozzo, Rush and Stephens is used to analyze both existing fixturing and redesigned fixturing setups. Flexible fixturing technologies have the potential to reduce prototype and small production run assembly time by reducing fixturing production time as well as accommodating various design changes common to prototype situations. While many such systems are already in existence, a selection of custom holding devices can be produced work in concert with the flexible fixturing systems already available. These features should be created with a product family design in mind, so future assemblies can reuse custom-made holding devices. Some of these technologies are then used to create a flexible fixturing conceptual design, which would be a replacement to the fixturing used in a subassembly of a composite-bonded UAV body. This fixturing is modeled using tolerance chains to determine the degree of accuracy expected. A subset of this fixturing is then assembled and tested to determine the actual accuracy that can be expected, as well as the repeatability and time savings over the original fixturing.