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This article presents analytical friction prediction models applicable to lubricants in point contacts under thermal elastohydrodynamic lubrication (TEHL). The types of models used consider the heat generated and its penetration into the bulk of the contacting solids. Therefore, the increase in temperature is determined, which causes important variations in the operating conditions. The article sets out the hypotheses assumed, the theoretical calculation procedures and the ensuing equations for determining the friction coefficient under TEHL. An experimental stage is performed on a mini-traction-machine, which allows the measurement of friction coefficient in ball–disc contacts under a wide range of control parameters involved in TEHL, such as lubricant bath temperature, load, average velocity, slide-to-roll ratio, and contacting materials. The experimental results for different lubricants are compared to those given by the models, and show the proposed models to be accurate for predicting the friction coefficient.

This study is focused on obtaining intelligent structures manufactured from shape memory polymers possessing the ability to change their geometry in successive or 'step-by-step' actions. This objective has been reached by changing the conventionally used shape memory activation systems (heating resistance, laser or induction heating).The solution set out consists in using Peltier cells as a heating system capable of heating (and activating) a specific zone of the device in the first activation, while the opposite zone keeps its original geometry. By carefully reversing the polarity of the electrical supply to the Peltier cell, in the second activation, the as yet unchanged zone is activated while the already changed zone in the first activation remains unaltered.We have described the criteria for the selection, calibration and design of this alternative heating (activation) system based on the thermoelectric effect, together with the development of different 'proof of concept' prototypes that have enabled us to validate the concepts put forward, as well as suggest future improvements for 'intelligent' shape memory polymer-based devices.

This paper analyses the applicability of artificial neural networks for predicting the lubricated friction coefficient. We will consider their use as faster and simpler alternatives to simulations based on theoretical behaviour equations. The development of several different artificial neural networks is presented. They have been trained through tribological tests on a mini‐traction‐machine, which furnishes the friction coefficient in point contacts. Once the training has been completed the networks are applied as tools for predicting the results in different operating conditions. Their advantages and disadvantages are analysed compared with conventional simulation tools. Copyright © 2013 John Wiley & Sons, Ltd.

Although the use of personalized annuloplasty rings manufactured for each patient according to the size and morphology of their valve complex could be beneficial for the treatment of mitral insufficiency, this possibility has been limited for reasons of time-lines and costs as well as for design and manufacturing difficulties, as has been the case with other personalized implant and prosthetic developments. However, the present quality of medical image capture equipment together with the benefits to be had from computer-aided design and manufacturing technologies (CAD-CAM) and the capabilities furnished by rapid prototyping technologies, present new opportunities for a personalized response to the development of implants and prostheses, the social impact of which could turn out to be highly positive. This paper sets out a personalized development of an annuloplasty ring based on the combined use of information from medical imaging, from CAD-CAM design programs and prototype manufacture using rapid prototyping technologies.

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Abstract:This article shows different friction prediction models applicable to lubricants in point contacts under an elastohydrodynamic regime. The types of models used are two variations of the Newtonian theory, the Limiting Shear Stress model and the one based on Carreau's equation. The article sets out the theoretical calculation procedures and the ensuing equations for calculating the friction coefficient.The aims of the article are to study the effect of the parameters with influence on friction and to compare the model's results with those given by an experimental stage performed on a mini traction machine. This test system allows the measurement of friction coefficient in point contacts (ball-disc) under a wide range of variation of parameters such as temperature, slide-roll ratio, lubricant, material, load, or velocity.