Wyniki wyszukiwania - BazTech

1

Optimization of gear teeth in the wind turbine drive train with gear contact’s uncertainty using the reliability-based design optimization

Lee Changwoo, Park Yonghui

Archive of Mechanical Engineering

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2022

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LXIX, nr 4

713--728

EN

Although gear teeth give lots of advantages, there is a high possibility of failure in gear teeth in each gear stage in the drive train system. In this research, the authors developed proper gear teeth using the basic theorem of gear failure and reliability-based design optimization. A design variable characterized by a probability distribution was applied to the static stress analysis model and the dynamics analysis model to determine an objective function and constraint equations and to solve the reliability-based design optimization. For the optimization, the authors simulated the torsional drive train system which includes rotational coordinates. First, the authors established a static stress analysis model which gives information about endurance limit and bending strength. By expressing gear mesh stiffness in terms of the Fourier series, the equations of motion including the gear mesh models and kinematical relations in the drive train system were acquired in the form of the Lagrange equations and constraint equations. For the numerical analysis, the Newmark Beta method was used to get dynamic responses including gear mesh contact forces. From the results such as the gear mesh contact force, the authors calculated the probability of failure, arranged each probability and gear teeth, and proposed a reasonable and economic design of gear teeth.

2

Acute effects of different orthoses on lower extremity kinetics and kinematics during running; a musculoskeletal simulation analysis

Sinclair Jonathan, Ingram Jane, Taylor Paul John, Chockalingam Nachiappan

Acta of Bioengineering and Biomechanics

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2019

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Vol. 21, no. 4

13--25

EN

The current investigation aimed to examine the effects of different orthotic conditions on the biomechanical mechanisms linked to the aetiology of chronic pathologies using musculoskeletal simulation. Methods: 16 male and 20 females ran over an embedded force plate at 4.0 m/s, in five different conditions (medial, lateral, no-orthoses, semi-custom and off the shelf). Kinematics of the lower extremities were collected using an eight-camera motion capture system and lower extremity joint loading also explored using a musculoskeletal simulation approach. Differences between orthoses conditions were examined using 2  2 mixed ANOVA. Results: External instantaneous load rate was significantly reduced in the off the shelf orthoses (male = 1290.60 and female = 1567.10 N/kg/s), compared to the medial (male = 1480.45 and female = 1767.05 N/kg/s) and semi-custom (male = 1552.99 and female = 1704.37 N/kg/s) conditions. In addition, peak patellofemoral stress was significantly lower in the off the shelf orthoses (male = 68.55 and female = 94.91 KPa/kg) compared to the lateral condition (male = 70.49 and female = 103.22 KPa/kg). Finally, peak eversion angles were significantly attenuated in the medial orthoses (male = –6.61 and female = –7.72 deg) compared to the lateral (male = –9.61 and female = –10.32 deg), no-orthoses (male = –8.22 and female = –10.10 deg), semi-custom (male = –8.25 and female = –9.49 deg) and off the shelf (male = –7.54 and female = –8.85 deg) conditions. Conclusions: The current investigation shows that different orthotic devices/ configurations may provide distinct benefits in terms of their effectiveness in attenuating the biomechanical parameters linked to the aetiology of chronic running injuries.

3

A simple tridimensional processing of acceleration measurements for dynamic movements monitoring of sportsmen

Neneman K., Łuczyk A. W., Szostak S., Pleskacz W. A.

International Journal of Microelectronics and Computer Science

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2016

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Vol. 7, nr 2

47--53

EN

Measuring, monitoring and analysis of dynamic movements in sports is becoming more important than ever. Many methods used currently may only be applied in the artificial environment of a laboratory. Other methods require too much processing to be used during a real-time competition. To overcome these difficulties acceleration measurements and a simple method to process them have been proposed. Data processing is based on search and recognition of the characteristic points in the tridimensional representation of acceleration measurements. Three different dynamic movements have been measured: run, jump and punch. The presented results show that the measurements of acceleration and proposed processing may be used to extract movement parameters of a sportsman and monitor the level of his tiredness.

4

Wybrane aspekty eksploatacji pojazdu w warunkach ruchu miejskiego

Witaszek K., Witaszek M.

Logistyka

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2015

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nr 4

6637--6644, CD2

PL

Wśród licznych czynników decydujących o bezpieczeństwie ruchu samochodowego oraz jego wpływie na środowisko naturalne istotną rolę odgrywają parametry pracy pojazdu. Wysokie natężenie ruchu zwiększa zanieczyszczenie powietrza i ilość wypadków drogowych. Ma to miejsce w ruchu miejskim. W pracy przedstawiono wyniki badań wybranych parametrów pracy pojazdu przy poruszaniu się w takim ruchu. Analizowano: prędkość jazdy, czas postojów, udział jazdy na poszczególnych biegach, przy różnych stopniach otwarcia przepustnicy i prędkościach obrotowych wału korbowego silnika. Określono także wpływ tych czynników na zużycie paliwa. Stwierdzono, że jazda na najwyższym biegu, możliwym w danych warunkach i przy ograniczonej prędkości obrotowej, wynikającej ze stosunkowo niewielkiego (ok. 30%) otwarcia przepustnicy, poprawia ekonomikę jazdy.

EN

Among numerous factors that determine traffic safety and its influence on environment vehicle operating conditions play an important role. High street traffic volume increases air pollution and number of accidents. It takes place in urban traffic. This work presents a study of chosen operating conditions of a passenger car in such type of traffic. Cruise speed, idle time, gear use, throttle position and rotational speed were studied. Their influence on fuel consumption was determined. It was stated, that use of the highest, possible gear as well as moderate rotational speed, resulting from relatively low throttle opening (about 30%), has beneficial influence on driving economy.

5

Identyfikacja parametrów chodu swobodnego i biegu metodami numerycznymi

Głowiński S.

Logistyka

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2015

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nr 4

7483--7490, CD2

PL

Ocena chodu i biegu ma istotne znaczenie przy identyfikacji chorób związanych z układem ruchu. W celu wyznaczenia określonych parametrów można wykorzystać specjalistyczne oprogramowanie jak BTS, SkillSpector oraz czujniki ProMove mini. Pacjent porusza się ze stałą prędkością na bieżni. Uzyskane wyniki są następnie przekształcane za pomocą funkcji trygonometrycznych dla prawej i lewej kończyny, przez co uzyskuje się kąty w odpowiednich stawach. Znormalizowanie danych na poszczególne kroki i podział na fazy w każdym kroku pozwala na wyznaczenie asymetrii podczas ruchu. Poprzez zastosowanie metod numerycznych, za pomocą szeregu trygonometrycznego Fouriera oraz sumy sinusów uzyskuje się parametry każdego ze stawów w poszczególnych fazach kroku. Można je wykorzystać do planowania trajektorii egzoszkieletu wspomagającego proces rehabilitacji. Dokładność dopasowania określa się za pomocą błędu średniokwadratowego.

EN

The identification of typical parameters of gait and running is very important in estimation of diseases associated with human motor system. In order to determine the specific parameters, the specialized software like BTS, SkillSpector an ProMove mini sensor can be used. The user is moved at a constant speed on a treadmill. The results obtained are then converted by using of trigonometric functions for right and lef leg, thereby forming angles in the respective joints. The data for each step are standardized, and phasing in every step to determine the asymmetry in the motion. Through the use of numerical methods (eg. Matlab package), trigonometric Fourier series and the sum of sines, parameters are obtained of each of the joints in the individual phases step. They can be used to plan the trajectory of the exoskeleton eg. supporting the rehabilitation process. The accuracy of the fit is determined by a mean square error.

6

Lubrication in helical gears

Mordukhovich G., Anderson N.

International Journal of Applied Mechanics and Engineering

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2002

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Vol. 7, no 3

911-921

EN

A method to determine elastohydrodynamic film thickness in helical gears is developed by combining the Dowson-Higginson EHD formulation with helical gear geometry and kinematics. Comparisons are made to traditional gear film thickness models. This analysis is then used to characterize film thickness and lambda ratio in automotive planetary gearset. Methods to measure surface roughness in fine pitch gears are described.

7

A contribution to the optimal choice of the HCR-gears regarding frictional losses

Krizan B., Basan R., Lovrin N.

International Journal of Applied Mechanics and Engineering

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2002

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Vol. 7, Spec. is

249-254

EN

High transverse contact ratio (HCR) gears are non-standard involute gears with a transverse contact ratio ea>2 which proved adequate for use in automobiles, trucks, aircrafts and ships. The paper deals with the dependence of the sliding friction losses on HCR spur gears geometry such as pressure angle, tooth height, gears centre distance resp. addendum modification coefficients sum, addendum modification coefficients sum distribution and other parameters. The calculations are based on the comparison between the values of the sliding friction loss geometrical factor, which comprises the influence of the magnitude, and form of the toothing. A proper choice of these parameters is necessary for achieving good gearbox efficiency. The calculations results are shown in diagrams which can be a tribological guideline to a designer in choosing gears optimal geometrical parameters.