Juan Manuel Munoz-Guijosa

Development of Personalized Annuloplasty Rings: Combination of CT Images and CAD-CAM Tools

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 timelines 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.

Analytical model for predicting the friction coefficient in point contacts with thermal elastohydrodynamic lubrication

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.

Models for Predicting Friction Coefficient and Parameters with Influence in Elastohydrodynamic Lubrication

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 Carreaus 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 models 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.

Towards a safety index for assessing head injury potential in service robotics

There are many standards worldwide dealing with safety issues in robots and adequate protections for their industrial use. Two main safeguard actions are considered to avoid mechanical risks, namely physical or non-physical protections and design guidelines for robots and their components. Nevertheless, there is a lack of specific standards for service robots. Safety in these robots needs a new point of view. It requires a strategy to be changed from pre-contact to post-contact safety, since it is not possible to avoid human–robot interaction. On the other hand, in automotive industry crash test results are used for assessing car safety by means of safety indices. In this paper, quantitative head injury indices for automobiles are analysed and a new safety index for robots NIR is derived. The similitude between NIR and indices used in automotive industry lets the new index to take advantage of previous results and knowledge available in automotive field. Results with NIR are compared with those given by experimental tests with robots. The effects of main parameters on the new index are analysed and results are compared with other safety criteria in order to clarify differences and benefits.

Optimising lubricated friction coefficient by surface texturing

Surface texturing has proved to be a very useful tool for expanding the behaviour under hydrodynamic and elastohydrodynamic regimes instead of mixed or boundary lubrication regimes, and therefore for reducing the friction coefficient under high-load low-speed conditions. This article presents the texturing of different copper test-samples using photolithography and chemical etching to measure the friction coefficient using a point contact machine. The effects of texture size, texturing density, the initial roughness of the samples and the operating conditions have all been studied. Some combinations of texturing density and texture size achieve up to 30% reduction in the friction coefficient. Taking into account experimental data, artificial neural networks are used as a tool for both predicting and optimising the friction coefficient on the textured surface for any given operating condition.

Elastohydrodynamic Models for Predicting Friction in Point Contacts Lubricated with Polyalphaolefins

This paper shows the results of a comparison between theoretical models for predicting friction in point contacts under elastohydrodynamic lubrication and the experimental results obtained in a Mini Traction Machine (MTM). The types of models used are two variations of the Newtonian Theory, applicable to polyalphaolefins (PAO): the Limiting Shear Stress Model and the Carreau’s model. The experimental stage includes a wide variation of the operating conditions, by using different control parameters, such as temperature, contact materials, slide-roll ratio, sliding velocity and load.

Stress - Strain Simulations for Optimising the Design of Shape - Memory Polymer Based Annuloplasty Rings

Shape-memory polymers are active materials that provide a mechanical response to temperature changes. They have a high capability for recovering from deformations (much greater than shown by shape-memory alloys) which combined with a lower density and cost has favoured the appearance of numerous applications for manufacturing actuators, especially for the aeronautics, automobile and medical industries.

Analysis of different multiaxial fatigue criteria in the prediction of pitting failure in spur gears

The aim of this article is to study the appearance of pitting in spur gears by taking account of different multiaxial fatigue criteria. The stress levels undergone by the teeth are considered in order to be able to predict their life and compare the fatigue strength of gear materials. The process begins calculating the stress field inside the teeth flanks due to the pressure and shear stress in the contact along the mesh. Once the stresses are known, the appearance of failure is studied by using different multiaxial fatigue criteria: Dang Van, Crossland and Liu-Mahadevan criteria. The accuracy of each criterion to predict pitting in gears is analysed using experimental data.

Royal Manufactures Promoted by the Spanish Crown during the 18th and 19th Centuries: An Approach to European Industrialisation

This work presents the Royal Factories promoted by the Spanish crown in the 18th and 19th centuries in the context of European industrialisation. They are classified together with the main types of factories and some specific examples are described. The article includes a discussion on the conditions that promoted their proliferation as the precursors of present-day state-owned industry, as well as the main causes that led to their decline.

Methods to Promote Creativity and Technological Transfer

The different technological advances commented in previous chapters provide a broad range of tools for promoting the development process of novel biodevices, and multidisciplinary teams are sometimes needed to master and integrate all of them, so as to maximize their benefits for the development process.