Virtual assembly rapid prototyping of near net shapes

Virtual reality (VR) provides another dimension to many engineering applications. Its immersive and interactive nature allows an intuitive approach to study both cognitive activities and performance evaluation. Market competitiveness means having products meet form, fit and function quickly. Rapid Prototyping and Manufacturing (RP&M) technologies are increasingly being applied to produce functional prototypes and the direct manufacturing of small components. Despite its flexibility, these systems have common drawbacks such as slow build rates, a limited number of build axes (typically one) and the need for post processing. This paper presents a Virtual Assembly Rapid Prototyping (VARP) project which involves evaluating cognitive activities in assembly tasks based on the adoption of immersive virtual reality along with a novel non-layered rapid prototyping for near net shape (NNS) manufacturing of components. It is envisaged that this integrated project will facilitate a better understanding of design for manufacture and assembly by utilising equivalent scale digital and physical prototyping in one rapid prototyping system. The state of the art of the VARP project is also presented in this paper

Virtual bloXing - assembly rapid prototyping for near net shapes

Virtual reality (VR) provides another dimension to many engineering applications. Its immersive and interactive nature allows an intuitive approach to study both cognitive activities and performance evaluation. Market competitiveness means having products meet form, fit and function quickly. Rapid Prototyping and Manufacturing (RP&M) technologies are increasingly being applied to produce functional prototypes and the direct manufacturing of small components. Despite its flexibility, these systems have common drawbacks such as slow build rates, a limited number of build axes (typically one) and the need for post processing. This paper presents a Virtual Assembly Rapid Prototyping (VARP) project which involves evaluating cognitive activities in assembly tasks based on the adoption of immersive virtual reality along with a novel nonlayered rapid prototyping for near net shape (NNS) manufacturing of components. It is envisaged that this integrated project will facilitate a better understanding of design for manufacture and assembly by utilising equivalent scale digital and physical prototyping in one rapid prototyping system. The state of the art of the VARP project is also presented in this paper

The use of non-intrusive user logging to capture engineering rationale, knowledge and intent during the product life cycle

Within the context of Life Cycle Engineering it is important that structured engineering information and knowledge are captured at all phases of the product life cycle for future reference. This is especially the case for long life cycle projects which see a large number of engineering decisions made at the early to mid-stages of a product's life cycle that are needed to inform engineering decisions later on in the process. A key aspect of technology management will be the capturing of knowledge through out the product life cycle. Numerous attempts have been made to apply knowledge capture techniques to formalise engineering decision rationale and processes; however, these tend to be associated with substantial overheads on the engineer and the company through cognitive process interruptions and additional costs/time. Indeed, when life cycle deadlines come closer these capturing techniques are abandoned due the need to produce a final solution. This paper describes work carried out for non-intrusively capturing and formalising product life cycle knowledge by demonstrating the automated capture of engineering processes/rationale using user logging via an immersive virtual reality system for cable harness design and assembly planning. Associated post-experimental analyses are described which demonstrate the formalisation of structured design processes and decision representations in the form of IDEF diagrams and structured engineering change information. Potential future research directions involving more thorough logging of users are also outlined

Automated design analysis, assembly planning and motion study analysis using immersive virtual reality

Previous research work at Heriot-Watt University using immersive virtual reality (VR) for cable harness design showed that VR provided substantial productivity gains over traditional computer-aided design (CAD) systems. This follow-on work was aimed at understanding the degree to which aspects of this technology were contributed to these benefits and to determine if engineering design and planning processes could be analysed in detail by nonintrusively monitoring and logging engineering tasks. This involved using a CAD-equivalent VR system for cable harness routing design, harness assembly and installation planning that can be functionally evaluated using a set of creative design-tasks to measure the system and users' performance. A novel design task categorisation scheme was created and formalised which broke down the cable harness design process and associated activities. The system was also used to demonstrate the automatic generation of usable bulkhead connector, cable harness assembly and cable harness installation plans from non-intrusive user logging. Finally, the data generated from the user-logging allowed the automated activity categorisation of the user actions, automated generation of process flow diagrams and chronocyclegraphs

ESR studies of some iron(II) spin crossover complexes.

X-band ESR powder studies have been done on the spin transition in Mn 2- doped [Fe(bpp)2][CF3SO3] 2·H2O, [Fe(bpp)2][BF4] 2 and [Fe(5NO2-sal N(1,4,7,10))] complexes. The use of Mn 2+ as an ESR probe in the studies is based on the knowledge that the ion is very sensitive to changes in its surrounding environment, enabling the changes within the system during HS ↔ LS crossover to be observed. The computer simulations of the powder ESR spectra of Mn2+ ion in these complexes using the SimFonia simulation program, obtained from Broker, gave numerical values of D and E for Mn2+ in the [Fe(bpp)2][CF3SO 3]2·H2O and [Fe(bpp)2][BF 4]2 systems. The magnitudes of D for Mn2+ ion are very different in the HS and LS phases of both the [Fe(bPP)2 ][CF3SO3]2·H2O and [Fe(bpp)2][BF4]2 systems, indicating that the spin transition in these systems is accompanied by a phase transformation. The spears show that during the transition there are separate domains for each spin state. Attempts to simulate the powder ESR spew of Mn2+ in [Fe(5-NO2-sal-N(1,4,7,10))] complex were unsuccessful owing to their poor quality, and further ESR study of this system was not pursued. In summary, ESR studies of [Fe(bpp)2][CF3SO 3]2·H2O show that the phase transformation is coupled to the thermally-induced spin crossover, whereas in [Fe(bpp) 2][BF4]2 the phase transformation takes place first. The rate of HS → LS phase transformation in the [Fe(bpp) 2][CF3SO3]2·H2O system, when the HS state is formed by rapidly cooling the HS state, is the same as the HS → LS conversion reported in the literature using magnetic susceptibility measurements. The rate of HS → LS phase transformation in the [Fe(bpp) 2][BF4]2 system, when the HS state is formed by rapidly cooling the HS state, is twice the rate of the spin-state transition reported in the literature using Mossbauer spectroscopy. There is also no evidence of a phase change seen in the ESR spectra of the [Fe(5-NO2-sal-N(1,4,7,10))] complex. (Abstract shortened by UMI.) Source: Dissertation Abstracts International, Volume: 61-09, Section: B, page: 4745. Adviser: Bruce R. McGarvey. Thesis (Ph.D.)--University of Windsor (Canada), 1998