Computer Aided Engineering

3-D printing has entered the consumer market because of recent radical price declines. Consumers can save substantial money by offsetting purchases with DIY pre-designed 3-D printed products. However, even more value can be obtained with distributed manufacturing using mass customization. Unfortunately, the average consumer is not technically sophisticated enough to easily design their own products. One solution to this is the use of an overlay on OpenSCAD parametric code, although current solutions force users to relinquish all rights to their own designs. There is thus a substantial need in the open source design community for a libre 3-D model customizer, which can be used in any design repository to democratize design. This study reports on the design, function, and validation of such software: the Free Open Source 3-D Customizer. It is demonstrated with a case study of the customization of 3-D printable external breast prosthetics. The results showed that novice users can adjust the available parameters according to their needs and save these to a new file on a website. This PHP (recursive acronym for PHP: Hypertext Preprocessor) library is free and open source and has potential for increasing the usefulness of online repositories to enable distributed manufacturing using consumer customized 3-D printable products.

The decline of critical habitat structures, such as large old trees, is a global environmental challenge. The cavities that occur in these trees provide shelter and nesting sites for many species but can take centuries to develop. Artificial cavities, including nest boxes and carved logs, offer an increasingly important conservation response. However, current methods of designing, manufacturing and deploying such habitats have constraints that limit innovation, feasibility and effectiveness. In response, this article aims to provide new and broadly useable methods that can improve the design of habitat structures for cavity-dependent animals. To address the shortcomings of existing methods, we develop an approach that uses computer-aided design techniques of generative and parametric modelling to produce structures that satisfy stakeholder needs, computer-aided manufacturing techniques of 3D printing and augmented-reality assembly to build functional prototypes, and computer-assisted techniques of laser scanning and data-driven design to support installation, monitoring and iterative improvement of designs. We demonstrate this approach through a case-study project that designs and instals habitat structures for the powerful owl Ninox strenua, a cavity-dependent and threatened bird. Through a comparison with existing methods, our pilot study shows that computer-aided design and manufacturing can provide novel and useful approaches to develop artificial habitat-structures. Computer-aided design finds geometries that approximate the complex characteristics of natural tree cavities and automatically produces new versions to suit diverse sites or species. Computer-aided manufacturing integrates materials that match the performance of naturally occurring habitat structures and facilitates the assembly of complex geometries by non-experts. Computer-assisted techniques produce precisely fitting and easy-to-instal designs, which support gradual improvement through ongoing prototyping and evaluation. These capabilities highlight how advanced design techniques can improve aspects of artificial habitat-structures through geometric innovation, novel construction techniques and iterative exploration. Significantly, computational approaches can result in designs that can perform well, are easy to construct and instal and are applicable in many situations. Our reusable workflow can aid in the tasks of practical conservation and support ecological research by effectively negotiating the needs of both humans and target species.

Beam-like members such as shafts, levers, frame components, beam structures, etc. are regularly designed and constructed in the field of mechanical and civil engineering. It is pertinent to know the structural integrity of the design before construction or fabrication. Beam deflection and stress calculations can be cumbersome and results from commercial simulation packages are not devoid of truncation and/or round-off errors because they are based on numerical schemes. To reduce or eliminate these issues, a computational tool, CABDA, has been designed and developed on matlab. The algorithm is based on analytic equations of beam deflection and bending stress theories; a design flow chart and graphic user interface were done to implement the algorithm. Experiments and simulations have been carried out for steel and brass rectangular beams which were compared with results obtained from CABDA for the same beam model. Average deflection errors recorded for steel beam are-0.4 and-0.015; for brass beam are-0.69 and-0.1 for experiment and simulation respectively. Average bending stress error recorded is-0.19 for simulation. It is observable that simulation results compare closely but CABDA gives exact results and therefore is very appropriate for simple beam problems.

During the practice of industrial design, digital methods are used to support the generation, development and specification of creative three dimensional (3D) form. Despite the increasing capabilities of digital methods, the distinctive nuances of current practice continue to use non-digital methods, particularly during the creative concept generation activities. This paper reports on a research project that combined emerging and established digital design technologies to define an approach for total ‘Digital Industrial Design’ (DID) that employs only digital methods (e.g. no pens/paper) with no post-process finishing (e.g. smoothing/painting of rapid prototype parts). The paper concludes that DID has the greatest potential for change and benefit during concept generation, where haptic feedback modelling and monochrome 3D printing have the capacity to replicate some of the qualities of tactile form-giving associated with workshop-based sketch modelling. To maximise impact, the case study was translated into in a web-based resource (http://www.lboro.ac.uk/microsites/lds/did/).

Mixing of high-viscosity liquids (e.g. glycerol–water solutions) is challenging and costly and often requires employing active mixing methods. Two-phase flow micromixers have attracted attention due to their low cost, simple structure, and high performance. In the present work, we investigate the mixing of similar fluids with viscosities equal to or higher than that of water in a two-phase (gas-liquid) slug-flow micromixer, as an economical passive design. Various cases are studied, in which the liquid samples to be mixed are either water or glycerol–water solution. The performance of the proposed slug-flow micromixer is compared with that of a single-phase micromixer with similar geometrical configuration. We demonstrate that mixing efficiencies higher than 90% are attainable for species with viscosities of about 54% higher than that of water (O(10−3) kg m−1 s−1); a result that is not attainable in the corresponding single-phase micromixer. Moreover, a mixing efficiency of more than 80% is achieved at the outlet of the micromixer for solutions with viscosities of 160% higher than that of water.