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This paper is concerned with the calibration and validation of a finite‐element model of dry sliding wear in metals. The model is formulated within a Lagrangian framework capable of accounting for large plastic deformations and history‐dependent material behavior. We resort to continuous adaptive meshing as a means of eliminating deformation‐induced element distortion, and of resolving fine features of the wear process such as contact boundary layers. Particular attention is devoted to a generalization of Archard’s law in which the hardness of the soft material is allowed to be a function of temperature. This dependence of hardness on temperature provides a means of capturing the observed experimental transition between severe wear rates at low speeds to mild wear rates at high speeds. Other features of the numerical model include: surface evolution due to wear; finite‐deformation J₂ thermoplasticity; heat generation and diffusion in the bulk; non‐equilibrium heat‐transfer across the contact interface; and frictional contact. The model is validated against a conventional test configuration consisting of a brass pin rubbing against a rotating steel plate.

This paper reports on the development of a simple manufacturing process for polymeric multilayer substrates utilising the thermoplasticity of thermoplastic resin. Features and defects noted in manufacturing trials of the substrates are also reported. The process involves a polymer‐based thick film conductive paste screen printed on a hole‐punched thermoplastic resin film and dried. The films are stacked to form multiple layers and are then compressed into one unit. As the extremely thin thermoplastic resin film layers are equivalent to a single layer, a feature of this substrate is its exceptional thinness. As thermoplastic resin is used as a base material, the soldering process and other connecting technologies which may be used in place of solder connection are also examined.

Among the wide selection of organic based surface coating materials, the fluorocarbon plastics have always been of particular interest for their ability to withstand aggressive chemical environments. The first widely known fluorocarbon was P.T.F.E. which has outstanding chemical resistance. Unfortunately this material is not a true thermoplastic and this fact has limited its application as a lining for tanks and vessels. Attention was turned to other fluorocarbon compounds and several alternatives have been used in industry, and although chemical resistance is slightly inferior to P.T.F.E. the chemically related fluorocarbons which possessed true thermoplasticity have been very useful to chemical engineers and those involved in the choice of lining materials. It is always attractive to the engineer to apply a suitable anti‐corrosive lining to an existing carbon steel vessel, rather than replace with an exotic material of construction. Lined carbon steel is usually a cheaper solution and much more readily available.

The purpose of this paper is to present a variational mesh h-adaption approach for strongly coupled thermomechanical problems.

The mesh is adapted by local subdivision controlled by an energy criterion. Thermal and thermomechanical problems are of interest here. In particular, steady and transient purely thermal problems, transient strongly coupled thermoelasticity and thermoplasticity problems are investigated.

Different test cases are performed to test the robustness of the algorithm for the problems listed above. It is found that a better cost-effectiveness can be obtained with that approach compared to a uniform refining procedure. Because the algorithm is based on a set of tolerance parameters, parametric analyses and a study of their respective influence on the mesh adaption are carried out. This detailed analysis is performed on unidimensional problems, and a final example is provided in two dimensions.

This work presents an original approach for independent h-adaption of a mechanical and a thermal mesh in strongly coupled problems, based on an incremental variational formulation. The approach does not rely on (or attempt to provide) error estimation in the classical sense. It could merely be considered to provide an error indicator. Instead, it provides a practical methodology to adapt the mesh on the basis of the variational structure of the underlying mathematical problem.

The purpose of this paper is to evaluate the energy consumed to fabricate nylon parts using selective laser sintering (SLS) and to compare it with the energy consumed for injection molding (IM) the same parts.

Estimates of energy consumption include the energy consumed for nylon material refinement, adjusted for SLS and IM process yields. Estimates also include the energy consumed by the SLS and IM equipment for part fabrication and the energy consumed to machine the injection mold and refine the metal feedstock required to fabricate it. A representative part is used to size the injection mold and to quantify throughput for the SLS machine per build.

Although SLS uses significantly more energy than IM during part fabrication, this energy consumption is partially offset by the energy consumption associated with production of the injection mold. As a result, the energy consumed per part for IM decreases with the number of parts fabricated while the energy consumed per part for SLS remains relatively constant as long as builds are packed efficiently. The crossover production volume, at which IM and SLS consume equivalent amounts of energy per part, ranges from 50 to 300 representative parts, depending on the choice of mold plate material.

The research is limited to material refinement and part fabrication and does not consider other aspects of the life cycle, such as waste disposal, distributed 2 manufacturing, transportation, recycling or use. Also, the crossover volumes are specific to the representative part and are expected to vary with part geometry.

The results of this comparative study of SLS and IM energy consumption indicate that manufacturers can save energy using SLS for parts with small production volumes. The comparatively large amounts of nylon material waste and energy consumption during fabrication make it inefficient, from an energy perspective, to use SLS for higher production volumes. The crossover production volume depends on the geometry of the part and the choice of material for the mold.

The purpose of this paper is to prepare a kind of novel multi‐layer core‐shell latex, and to evaluate the effect of the preparation methodology.

Core‐shell poly(siloxane)/polystyrene/polymethyl methacrylate (PSi/PSt/PMMA) latex particles were prepared by seeded‐emulsion polymerisation with three stages. The core of cured PSi was prepared with octamethyl cyclotetrasiloxane (D4) and tetraethoxysilane (TEOS) by co‐condensation. Using vinyltriethoxysilane (VTEOS) as coupling agent, functional PSi particles with vinyl groups on surfaces were prepared by hydrolysis and condensation of VTEOS in core formation stage. Then, the functional PSi particles were used as seeds to copolymerise with styrene and methyl methacrylate sequentially in shell stage I and stage II to form PSi/PSt/PMMA latex particles.

FTIR, TEM, DSC and XPS showed that the PSi/PSt/PMMA latex particles had multi‐layer core‐shell structure with cured PSi as core, PSt as shell I and PMMA as shell II.

In the present work, PSi/PSt/PMMA latex particles having multi‐layer core‐shell structure with cured PSi as core, PSt as shell I and PMMA as shell II were prepared. This methodology can be employed to prepare new functional materials for various applications.

Multi‐layer core‐shell particles offer a new area of material science that has wide applications in coatings or modified polymer materials production.

The method developed in the study reported in this paper provides a new strategy to develop new types of core‐shell materials with multi‐layer structure.

The main purpose of this paper is to present and compare two different models for bubble growth and foam formation and to conduct a thorough assessment in terms of their numerical implementation and prediction accuracy.

The two models are assessed and validated against experimental measurements. The first model is known as a single bubble growth model and treats the foaming process as a single bubble growing in a large pool with enough gas available for growth, while the second model (cell model) takes into account the finiteness of gas supply availability as well as the effects of surrounding bubbles. The models are based on the application of the conservation of continuity and momentum principles and on constitutive equations to represent the viscosity of the melt. The models are numerically implemented using a finite difference scheme and their predictions are compared against experimental measurements.

The results demonstrate that the single bubble model predicts an infinite bubble growth with time due to the assumption of unlimited supply of the blowing agent. Meanwhile the cell model gives an equilibrium bubble size because it accounts for gas depletion. From this work, it was concluded that the cell model is the best model that adequately describes experimental data.

The problem of bubble growth and foam formation is of great importance in the process industry as it plays a key role in diverse technological fields such as the production of foamed plastics.

The findings here are important for the appropriate modeling of bubble growth and foam formation and for scheduling and optimizing the process. A simple model will suffice for the early stage of the process while a cell model is more appropriate for the entire duration of the process.

The purpose of this paper is to determine the most‐practical means of transforming computer‐aided‐design models of custom clubfoot pedorthoses into functional pedorthoses for testing on patients in a clinical trial.

The materials used in conventional orthosis fabrication are not yet available for solid free‐form fabrication; therefore, to fabricate the pedorthoses, several approaches were considered, including direct manufacturing, additive‐based moulding, laser cutting of foam and combinations of several of these approaches.

The chosen approach of additively manufacturing the custom hard shell, and moulding the polyurethane‐foam insert, resulted in accurate, durable and effective pedorthoses that fit well, and could be adjusted as needed. The pedorthoses that were produced are currently being tested on the respective patients for their improvement in mobility and degree of clubfoot correction, and will continue through early 2010.

Additive manufacturing provides an ideal approach for generating the custom, end‐use hard‐ and soft‐layer patterns: each pedorthosis is truly unique; and the soft layer has regions of variable thickness. The advantage of this approach is the reduction in labour and the increase in degrees of design freedom available, compared to conventional methods of fabricating orthotic devices. Replacement inserts can be moulded in a matter of hours using this silicone‐moulding approach.

Several new approaches for fabricating custom orthotic devices were explored, and the related results are discussed. The goal of this paper is to convey the potential of the fabrication procedure used and lessons learned on this project to the rapid prototyping and orthotic communities.

Explores the possibility of preparing elastic and hard ebonite coatings, utilizing the properties of oligobutadienes without ending functional groups. Examines the vulcanization processes leading to formation of rubberizing ebonite coatings on samples of oligobutadienes. Finds that the most effective bonding material for non‐solution compositions is ebonite coatings.

The area of microfluidic systems has greatly enhanced the in vitro field of tissue engineering. Microfluidic systems such as microchannelled assays are now widely used for mimicking in vivo cell behaviour and studies into basic biological research. In certain cases engineered tissue cell design use 3D ordered geometrical configurations in vitro (such as microchannel assays) to reproduce native in vivo functions. The most common approach for manufacturing micro‐assays is now rapid prototyping (RP) technology. The choice of assay material is dependent on the proposed cell type and ultimately the tissue application. However, many RP technologies can be unsuitable for cell growth applications because of the construction methods and materials they employ. The purpose of this paper is to describe a comparison between two different RP 3D printing methods of fabrication and investigates the merits of each technology for direct cell culture applications using micro‐assays, while also examining the dispensing accuracy of both techniques.

Using a Thermojet and Spectrum Z510 printer pre‐designed micro‐assays incorporating different size microchannels are dispensed. The base materials of both methods are examined for cytotoxic effects while in solution with primary tendon fibroblasts (PFB) cells. After obtaining favorable results from the toxicology experiments, PFB cells are seeded onto the thermojet structures with a view to investigate cell adherence, encapsulation and how the channel width influences cell alignment.

This research concluded that the thermojet had a higher degree of accuracy when manufacturing structures that incorporate microchannels when compared with the Spectrum Z510. Both techniques show that the accuracy of the build decreases with reduction in channel width. The fact that the Spectrum Z510 structures have to be infiltrated with a hardening glue as a post‐processing technique (since the dispensed material is water‐based and hence soluble) causes a cytotoxic effect compared to the thermojet plastic which is not cytotoxic in solution with PFB cells. Seeding the PBF cells directly onto the thermoplastic structure caused problems due to the hydrophobic nature of the material and this necessitated the technique of soaking the structures in a collagen bath to penetrate the surface and reduce the interactions of hydrophobic species enhancing cell attachment and proliferation. Without this coating the thermojet structures induced strong hydrophobic interactions at the surfaces of the microchannels with the culture media resulting in non‐attachment and poor cell mortality.

This research paper describes a comparison between the base materials and methodology of two 3D printing techniques for applications in basic biological studies. This is achieved by analysing the dispensing accuracy of both technologies and the interaction between cells and surface at the interface.