Recent Patents on Mechanical Engineering - Volume 1, Issue 2, 2008

Microfluidic devices are being researched and developed for a variety of applications. This paper reviews the latest invention disclosures and recent research on micropumps with a particular emphasis on their application in biomedical fields. A brief description of the available actuation schemes, flow directing concepts and liquid chamber configurations for micropumping is provided with illustrative diagrams. Current mechanical micropump designs have been proposed, yet micropumps are yet to be commonly utilized in several biomedical applications. Thus, there is a need for new and novel pumping concepts that address the barriers to market of these devices. This paper reviews the latest micropump design concepts as put forth in recent patent applications. Various applications of micropumps used in biomedicine are reviewed, such as in micro total analysis systems and drug delivery devices.

Helical baffles offer a possible alternative to conventional baffles in shell-and-tube heat exchangers. They have advantages in increasing heat transfer efficiency, maintaining a reasonable pressure drop, anti-fouling and prolonging service time. In order to make best use of these advantages, various inventions are proposed. This paper initially introduces the helical baffled shell-and-tube heat exchangers and has a brief description of some old patents, and then outlines recent patents in this area and finally concludes with future developments expected in the helical baffled heat exchanger.

Exhaust Heat Recovery Unit (EHRU), also known as Exhaust Heat Exchanger, is a system that recovers the wasted thermal energy from the exhaust and makes use of it if possible. The heat recovery method is the main focus of EHRU. There are three common groups of EHRU. Each of them makes use of a different heat recovery mechanism: by coolant, by Stirling engine and by thermoelectric module. This paper shows patents in EHRU in recent years. It firstly explains the heat recovery mechanism of the three groups and the requirements. Then, it describes the working principle of how the thermal energy is recovered in respective invention and also shows the problems addressed by the inventors. Finally, it estimates the trend of the researches in the following years.

This paper presents a reliability analysis procedure that couples traditional and modified first and second order reliability methods in rectangular plates modeled using Ritz method. Both reliability methods are applicable to the implicit limit state functions through numerical models, like those based on the Ritz method. For traditional reliability approaches, the algorithms FORM and SORM use a Newton-Raphson procedure for estimate design point. In modified approaches, the algorithms are based on heuristic optimization methods such as Genetic Algorithms, Particle Swarm Optimization and Ant Colony Optimization. Numerical applications in static, dynamic and stability problems are used to illustrate the applicability and effectiveness of proposed methodology. These examples consist in a rectangular plates subjected to inplane external loads, material and geometrical parameters which are considered as random variables. The results show that the predicted reliability levels are accurate to evaluate simultaneously various implicit limit state functions with respect to static, dynamic and stability criterions. This manuscript also includes relevant recent patents in structural reliability analysis.

This paper reviews more than 25 patents filed mainly since year 1997 that propose technologies to improve surface coordinate measurement technique under contact-based and non-contact based systems. The patents surveyed have identified the need to develop a device that brings a novel application approach for 3D surface profile measurement. This paper presents outlined features of developed 3D surface profile measurement device, which is based on the contact based technique combined with several systems and sub-systems. Systems comprise of a profile measuring head (hereafter PMH), an object movement unit, data acquisition and reconstruction software. Sub-systems comprise of a PMH that contains closely packed variable resistors with long arms, multiplexed circuit, calibration module and a controller to drive stepper motors etc. This device interfaces with computer for automatic operations like control movement of work piece and PMH, data acquisition under a systematic way, and data reconstruction.

This paper presents the most recent and important research trends on the tribological behavior of different types of composite materials. For this the invention, methods, techniques, and design related to this area are discussed. The different trends of the friction and wear behavior of composite materials under different operating conditions are observed. The investigators showed that, the variation of friction coefficient and wear rate depends on normal load, sliding velocity, lubrication, and vibration etc. In this article, an attempt is made to provide an opportunity for the future researchers to identify the recent trend of these areas. It is expected that the applications of these results will contribute to the improvement of different concerned mechanical processes. This review article also includes relevant patents.

In this paper loads and stresses exerted on the bevel gears of a differential (differential of Peugeot 405 as a case study) in different operating conditions have been analyzed by using an improved Finite Element Method. For this purpose, various loading conditions, vehicle dynamics and power train forces on differential components have been defined. It has been shown that combination of turning and braking lead to the most severe loading condition. Then, according to the obtained forces, the mechanical behavior of the differential components has been numerically analyzed with a new FEM. In the proposed FEM, the tooth is considered as an identical substructure connected to the next in the circumferential direction while conventional methods assume each tooth as an isolated structure. Also various loading types and element sizes are examined to identify the appropriate loading and meshing. Then stresses and strains have been calculated and compared with standards and data bases. Results have been produced on the basis of strength and fatigue criteria by taking into account the bending and pitting of the gears. It has been shown that the pitting has the major role in designing the gears; and using these results material and hardness for the gears have been selected considering the recommended safety factors.

This paper provides an overview of the application of Accelerated Life Testing (ALT) models for reliability estimation to mechanical components. The reliability is estimated by considering a classical test plan using a sample system tested only under accelerated conditions. The time transformation function is considered as log-linear and three types of estimation are studied using parametric, Extended Hazard Regression (EHR) and semiparametric models. The paper is illustrated by a simulation example based on Ball bearings testing. The results are used to analyze and compare these estimation methods. The simulations have been repeated with and without censoring data in order to examine the asymptotic behavior of the different points estimate.

Topics such as passenger's safety, seat performance in the crashes, energy absorption by the seat, are the major concern in vehicle design. Automobile seat, as a member which is in direct interaction with the passenger, has a major rule in providing passenger's safety. Statistics show that rear-side collisions, which cause severe injuries, have the forth rank among other type of crashes. Moreover, three out of four injuries caused by such crashes, are neck injuries. Therefore, seat design has a major rule in reducing the severity of the neck injuries. In this study, the measurement of the energy index by using FEM based method has been introduced, and the technique to increase the energy absorption by the seat structure has been investigated, and the effect of design parameter-variation on the severity of injuries has been studied via the simulation of rear-side collision. In this article most important patents are also discussed.

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