The Results of Changing the Current Solution Concept of Universal Motor Gear Reducers with Helical Gears

By analysing and comparing the existing solutions of universal gear reducers with helical gears of the leading manufacturers, it can be noticed the effort to increase the load capacity of the gear reducer within the same axis height. In this way, the manufacturers can offer smaller (cheaper) gear reducers, as well as to simultaneously increase the values of the largest gear ratios. This concept enables the offer of lower-stage (cheaper) gear reducers with higher gear ratios in certain segments of gear ratios. By these efforts, it is reached the maximum, but the further increase is possible only by changing the current concept of universal gear drives. Within this paper, it is given an overv…

Computer Simulation Paradigm Regarding the Structure and Mechanical Characteristics of Human Long Bones

Given the complex form of the long bones, a quality method of geometrical modeling which provides a good result is that of the 3D modeling by reconstruction, using the principles of reverse engineering. One of the important problems that shall be taken into consideration while modeling is the one concerning the real structure of the bones. This aspect presents a lot of importance because from the point of view of the mechanical behavior, the bones are neither homogenate structures. In this paper a study of the long bones structures is undergone, and in relation to the modelated element (the human tibia) it is divided in areas (called constructive-anatomical entities) of different mechanical…

The experimental study of the hybrid fixation in ACL reconstruction

Abstract The article is approaching an interesting topic regarding ACL reconstruction using the hamstring tendons (semitendinosus and gracilis) as the graft. The initial graft fixation after ACL reconstruction is mechanical and it must assure the stability of the system until the biologic integration takes place. No fixation system is as strong as the native ACL insertion. Therefore, hibrid fixation like an improvement of simple fixation is a field worth studying. The fixation shown in this article is the Hybrid fixation consisting of direct fixation with interference screw and an extra cortical fixation over a cortical screw.

Different Methods of Artificial Intelligence Used for Optimization the Turning Process

In this paper, we realize a comparative study between some heuristics methods applied in turning operation in order to find optimal cutting parameters. We consider five different constraints aimed to achieve minimum total cost of machining. We have chosen the Simulated Annealing (SA) – a local search method, and Weighted-Sum Genetic Algorithm (WSGA) – a non-Pareto approach of a multi-objective optimization algorithm, based on a weighted aggregation of objectives. The aggregation may be with fixed weights or with random (variable) weights. The simulations showed that, even if it produces better results than the SA, WSGA with fixed weights, does not lead to optimum results, highlighting in th…

Vertical wind turbine with self-limitation system of speed

A review on biomechanics of the hallux valgus pathology and its surgical treatments

Abstract The present paper aims at an interdisciplinary field, regarding biomechanics aspects of the Hallux Valgus, which is a frequent deformity in our days. Owing to the importance of the study theme and the social impact, we consider it very important that the state of the art should be as detailed as possible, due to this condition being frequent in women and older people. The review will target recent research of the biomechanics of the foot, the test subjects being in normal conditions and also patients affected by Hallux valgus deformities; likewise, it will define important geometrical elements, which are required for the engineering approach of the issue. As well, the 3D modelling …

Experimental Studies Regarding Mechanical Behaviour of Textile Reinforcements Laminated Composite Materials

The aim of this paper is to determine the mechanical properties of textile reinforcements laminated composite material and to establish the influence of thickness about these properties. The composite material used for this is a laminated sheet of HGW 2082. In order to study the mechanical behaviour of these kinds of materials we select two experimental tests: uniaxial test and bending test. For the uniaxial test we have measured the maximum load, the maximum extension, the maximum tensile stress and the maximum tensile strain. Also, using an optical extensometer we measured the major and the minor strains. For the bending test we measured the maximum load and the maximum bending deflection…

Contributions regarding 3D modelling of biomechanics of the foot

Within this paper, a detailed study is elaborated regarding the human foot during both orthostatic and gait, the main goal being to develop 3D models which are very useful in the foot motion and loading state research. In order to elaborate the accurate 3D modelling of the human foot assembly, a thorough biomechanical study is done. Such a study was required due to the fact of the high anatomical complexity of the motions within the foot, taking into consideration the 26 bones and 33 joints consisting it. The research aims the CAD modelling of the biomechanics of the healthy subjects alongside with predisposed pathological conditions. The resulting models will have important utility in both…

Theoretical and Experimental Research on Mechanical Behavior of Layered Composites Laminates

The aim of the research of the experiment was to determine the mechanical characteristics of the composite layered material. There has been two types of experimental tests i.e. test for determining the tensile modulus of elasticity of the material, the maximum voltage and the elongation at break of the material. The second type of test is the flexural test was intended to determine the maximum load that the breaking is produced by bending.

Studies on predictive virtual models based on finite element analysis of the behaviour of geomembranes

The study shown in this paper presents the behaviour of geomembranes used at the ecological landfills. For this goal was used a method designed to elaborate the virtual models of 3D geomembrane with one ply or 2 plies disposed at 30°, 45° and 90° and based on this model there were developed a number of 20 particular cases. For each situation it was realized the nonlinear analyses for all the developed cases with different vertical pressures representing different loads for the waste layer (1m, 2m, 10m, 15m, 20m). The main results are obtained in graphical form and represent the Maximum tensions Von Mises and total displacements of the geomembrane.

Analysis the amount of lubrication and roughness of raceways on dynamic behavior on the ball bearing

The operating principle of rolling bearings generates vibrations that come from the periodic change in the stiffness of the bearing. The vibration level of the bearing depends on a large number of factors such as waviness, surface roughness of the raceways, deviation of the raceway radius, exploitation conditions, amount of lubrication in the bearing and other. This paper presents the influence of the roughness of the raceways and the amount of lubrication on the level of vibrations of the ball bearing, designation 6006. The determination of the influence of these parameters was done experimentally. The experiment was performed according conditions prescribed by ISO 15242-2, and the analysi…

Studies of the Solar Radiations' Influence About Geomembranes Used in Ecological Landfill

Abstract The study shown in this paper presents the behavior of geomembranes used at the ecological landfills. The influences of the solar radiations has a great importance regarding the correct mounting of the geomembranes. The mathematical model developed for the determination anytime and anywhere in the world for the next values and parameters: apparent solar time, solar declination, solar altitude, solar azimuth and incidence angle, zone angle, angle of sun elevation, solar declination, solar constant, solar flux density, diffuse solar radiation, global radiation, soil albedo, total radiant flux density and relational links of these values. The results of this model was used for creatio…

Biomechanical Study of the Osteoporotic Spine Fracture: Optical Approach

Background and objectives: Osteoporotic spine fractures represent a significant factor for decreasing quality of life in the elderly female population. Understanding the mechanisms involved in producing these fractures can improve their prevention and treatment. This study presents a biomechanical method to produce a vertebral fracture, conducted on a human spine segment, observing the displacements and strains in the intervertebral disc, endplate, and vertebral body. Materials and Methods: We performed two tests, one corresponding to an extension loading, and the second to an axial loading. Results: The maximum displacement in the target vertebral body presented higher values in the case o…

Implementing some Evolutionary Computing Methods for Determining the Optimal Parameters in the Turning Process

In this paper, we comparatively present two heuristics search methods – Simulated Annealing and Weighted Sum Genetic Algorithm, in order to find optimal cutting parameters in turning operation. We consider five different constraints aiming to achieve minimum total cost of machining. We developed a customizable software application in Microsoft Visual Studio with C# source code, flexible and extensible that implements the optimization methods. The experiments are based on real data gathered from S.C. “Compa” S.A Sibiu, a company that manufactures automotive components and targets improving of product quality and reducing cost and production time. The obtained results show that, although the …

Experimental Study Regarding of Bending Behaviour of Stabilizator Link

Abstract This paper presents an experimental study of the behavior of anti-roll power link subjected to bending, power link coming from an Opel Astra G. The power link is made of PA66 GF30 polyamide. For this study, there were used a universal testing machine (Instron 5587) and a real-time strain measurement optical system (Aramis). The results showed are those obtained in the case of a compression force of 1,000 [N] namely: major Strain ε1, minor strain ε2, equivalent von Mises strain, displacement on X axis, displacement on Y axis (compression force direction), displacement on Z axis.

Designing a Specialized Devices for Correction of the Axis Deviation at the Human Leg

The presented article is an original contribution which implies the design of a specialized device for high tybial osteotomy (HTO) optimization. In the papers are presented the sources that imply HTO, the axial deviations of the human lower member from the correct position. This sources are the gonarthosys owed to the usage of the knees cartilages or owed to some diseases (such as the Blount disease) and the vicious consolidated fractures. After presenting the needs to realize such a specialized device for HTO, the principal requests the device shall fulfill are underlined. Starting from these , two sub ensembles were projected, one for the tibial positioning and for the execution of the ho…

Customizable Patient-Specific Cutting Guide for High Tibial Osteotomy

Abstract The paper is an interdisciplinary medical and engineering approach that aims to optimize the accuracy of the High Tibial Osteotomy surgical intervention. The axial deviations of the human inferior limb are presented in the first part of the paper. Without altering the shape of the bones, these deviations cause the wear of the knee’s articular cartilage by gonarthrosis. One of the most common and effective treatment modalities for eliminating axial deviations is High Tibial Osteotomy. Because the surgical procedure involves 3D spatial bone cutting, the accuracy of the procedure and thus the success of the operation and the recovery of the patient is dependent on the execution of the…

Parametric Modeling CAD-CAM of the Ankle and Pathological Related Situations

It is primary object of the present study to create a 3D model of the human ankle and an axis system that will show the position the tibia and the foot on a healthy subject. Regarding this scope of the study, the first step in obtaining the 3D model of the bones is scanning. The graphic modeling software used is Catia V5 R20. It is another object of the present study to create an axis system that will be very easy to maneuver and on which we can show different pathological situations, not only on a healthy subject, creating their assembly reference systems considering the mechanical and anatomical axes existing and creating prerequisites for the study of different possible pathological situ…

Modular device used in the surgery of the human tibia

Analysis of Possible Concept Solutions of Chain Drives

Possible concept solutions of chain drives are analysed in this paper in order to point out the benefits of chain drive application and, in particular, the possibility of application of multi-level chain drive. The paper also analyses the possibility of replacing the gear drives with chain drives, which, in the case of short-term drive and using the same direction of rotation, enables a slightly simpler drive solution. The paper doesn’t consider difference between the roller and gear chains application because these two types of chains can be used very successfully. Also, the possibility of using timing belt drive is not considered, but it can be also used very successfully in this type of …