Issue 2
JTAM, Sofia, vol. 46 Issue 2 (2016)

One Approach to the Synthesis, Design and Manufacture of Hyperboloid Gear Sets with Face Mating Gears. Part 1: Basic Theoretical and CAD Experience

Valentin Abadjiev, Emilia Abadjieva


Hyperboloid gear drives with face mating gears are used to transform rotations between shafts with non-parallel and non-intersecting axes. A special case of these transmissions are Spiroid1 and Helicon gear drives. The classical gear drives of this type are the Archimedean ones. The objective of this study are hyperboloid gear drives with face meshing, when the pinion possesses threads of conic convolute, Archimedean and involute types, or the pinion has threads of cylindrical convolute, Archimedean and involute types. For simplicity, all three types transmissions with face mating gears and a conic pinion are titled Spiroid and all three types transmissions with face mating gears and a cylindrical pinion are titled Helicon. Principles of the mathematical modelling of tooth contact synthesis are discussed in this study. The presented research shows that the synthesis is realized by application of two mathematical models: pitch contact point and mesh region models. Two approaches for synthesis of the gear drives in accordance with Olivier’s principles are illustrated. The algorithms and computer programs for optimization synthesis and design of the studied hyperboloid gear drives are presented.

JTAM, Sofia, vol. 46 Issue 2 pp. 03-26 (2016), [Full Article]

Roughness Measurement of Dental Materials

Assen Shulev1, Ilia Roussev1, Simeon Karpuzov1, Georgi Stoilov1, Detelina Ignatova1, Constantin von See2, Gergo Mitov2
1Institute of Mechanics, Bulgarian Academy of Sciences, Acad. G. Bonchev St., Bl. 4, Sofia 1113, Bulgaria
2Steiner Landstraße 124 A-3500, Krems-Stein, Austria

This paper presents a roughness measurement of zirconia ceramics, widely used for dental applications. Surface roughness variations caused by the most commonly used dental instruments for intraoral grinding and polishing are estimated. The applied technique is simple and utilizes the speckle properties of the scattered laser light. It could be easily implemented even in dental clinic environment. The main criteria for roughness estimation is the average speckle size, which varies with the roughness of zirconia. The algorithm used for the speckle size estimation is based on the normalized autocorrelation approach.

JTAM, Sofia, vol. 46 Issue 2 pp. 27-36 (2016), [Full Article]

Mechatronic Scanning System with Integrated Micro Electro Mechanical System Position Sensors

Vladimir Stavrov1, Dimitar Chakarov2, Assen Shulev2, Mihail Tsveov2
1AMG Technology Ltd., Botevgrad, Bulgaria
2Institute of Mechanics, Bulgarian Academy of Sciences, Acad. G. Bonchev St., Bl. 4, 1113 Sofia, Bulgaria

In this paper, a study of a mechatronic scanning system for application in the microbiology, microelectronics research, chemistry, etc. is presented. Integrated silicon micro electro mechanical system (MEMS) position sensor is used for monitoring the displacement of the scanning system. The utilized silicon MEMS sensors with sidewall embedded piezoresistors possess a number of key advantages such as high sensitivity, low noise and extremely low temperature dependence. Design of 2D scanning system with a travel range of 22 × 22 μm2 has been presented in present work. This system includes a Compliant Transmission Mechanism, (CTM) designed as a complex elastic mechanism, comprising four parallelograms. Computer aided desigh (CAD) model and finite element analysis (FEA) of the Compliant Transmission Mechanism mechanisms have been carried out. A prototype of the scanning system is fabricated, based on CAD model. An experimental set-up of an optical system and a correlation technique for digital image processing have been used for testing the scanning system prototype. Results of the experimental investigations of the prototyped scanning system are also presented. Key words: Scanning system, micro electro mechanical system (MEMS) sensor, piezoresistors, transmission mechanism, finite element analysis (FEA) simulations, experimental set-up, digital image processing.

JTAM, Sofia, vol. 46 Issue 2 pp. 37-50 (2016), [Full Article]

Automatic Bone Drilling – More Precise, Reliable and Safe Manipulation in the Orthopaedic Surgery

George Boiadjiev1,2, Rumen Kastelov3, Tony Boiadjiev4, Kamen Delchev2, Kazimir Zagurski5
1Faculty of Mathematics and Informatics, Sofia University, 5 J. Boucher Blvd, 1164 Sofia, Bulgaria
2Institute of Mechanics, Bulgarian Academy of Sciences, Acad. G. Bonchev, blok 4, 1113 Sofia, Bulgaria
3Orthopaedic and Trauma Clinical Centre of Ministry of Domestic Affairs, 79 Skobelev Blvd, 1606 Sofia, Bulgaria
4Institute of Information and Communication Technologies Bulgarian Academy of Sciences, Acad. G. Bonchev St., Bl. 2, 1113 Sofia, Bulgaria
5Institute of System Engineering and Robotics Bulgarian Academy of Sciences, Acad. G. Bonchev St., Bl. 2, 1113 Sofia, Bulgaria

Bone drilling manipulation often occurs in the orthopaedic surgery. By statistics, nowadays, about one million people only in Europe need such an operation every year, where bone implants are inserted. Almost always, the drilling is performed handily, which cannot avoid the subjective factor influence. The question of subjective factor reduction has its answer – automatic bone drilling. The specific features and problems of orthopaedic drilling manipulation are considered in this work. The automatic drilling is presented ac- cording the possibilities of robotized system Orthopaedic Drilling Robot (ODRO) for assuring the manipulation accuracy, precision, reliability and safety.

JTAM, Sofia, vol. 46 Issue 2 pp. 51-64 (2016), [Full Article]

Internal Heat Source in Thermoelastic Microelongated Solid Under Green Lindsay Theory

Praveen Ailawalia1, Sunil Kumar Sachdeva2,3, Devinder Singh Pathania4
1Department of Applied Sciences and Humanities, Maharishi Markandeshwar University, Sadopur, Ambala, Haryana, India
2Department of Applied Sciences, D.A.V Institute of Engineering and Technology, Jalandhar, Punjab, India
3Research Scholar, IKG Punjab Technical University, Jalandhar, Punjab, India
4Department of Applied Sciences, Guru Nanak Dev Engineering College, Ludhiana, Punjab, India

The present study deals with two dimensional deformation, due to internal heat source in a thermoelastic microelongated solid. A mechanical force is applied along the interface of elastic half space and thermoelastic microelongated half space. The problem is in the context of Green Lindsay (GL) theory. The analytic expressions for displacement component, normal force stress, temperature distribution and microelongation have been derived. The effect of internal heat source and microelongation on the derived components have been depicted graphically.

JTAM, Sofia, vol. 46 Issue 2 pp. 65-82 (2016), [Full Article]

Motion of a Point Mass in a Rotating Disc: A Quantitative Analysis of the Coriolis and Centrifugal Force

Soufiane Haddout
Department of Physics, Faculty of Science, Ibn Tofail University, B. P. 242, 14000 Kenitra, Morocco

In Newtonian mechanics, the non-inertial reference frames is a generalization of Newton’s laws to any reference frames. While this approach simplifies some problems, there is often little physical insight into the motion, in particular into the effects of the Coriolis force. The fictitious Coriolis force can be used by anyone in that frame of reference to explain why objects follow curved paths. In this paper, a mathematical solution based on differential equations in non-inertial reference is used to study different types of motion in rotating system. In addition, the experimental data measured on a turntable device, using a video camera in a mechanics laboratory was conducted to compare with mathematical solution in case of parabolically curved, solving non-linear least-squares problems, based on Levenberg-Marquardt’s and Gauss-Newton algorithms.

JTAM, Sofia, vol. 46 Issue 2 pp. 83-96 (2016), [Full Article]