Vibration analysis of a small diesel engine using diesel-biodiesel fuel blends

Biodiesel as an environmentally friendly fuel has the potential to provide comparable engine performance results.  Biodiesel is a renewable fuel produced from vegetable and seed oils, animal fats or waste edible oils.  Sound and vibration caused by the combustion process in the engine might have direct effects on users.   One of the important characteristics of diesel fuels is high noise and vibration.  The present study was carried out to examine the vibration of different diesel-biodiesel fuel blends in power tiller engine.  The main goal was to present fuels with the minimum vibration.  So, the time domain signals were analyzed in five levels of engine speed, three axes and six fuel blends on the engine.  The signal processing and statistical approach were applied for data analysis.  The results showed that in all engine speeds, the dominant frequency is matched to the piston stroke frequency of the engine, as well as the frequency of vibration with the increase of engine speed.  The experiments indicated that the magnitude of vibration in the power tiller engine depends on the axis of measurement, engine speed and the fuel blends.  Vibration acceleration is significantly affected by engine speed and the increase in forward speed due to the increase in vibration acceleration rms.  The results of the experiments revealed that vibration acceleration is significantly affected by the axis of measurement.  The magnitude of vibration acceleration in vertical axis was more than that in the other two axes and magnitude of vibration acceleration in the longitudinal axis was more than that in the lateral axis.  Fuel blends had significant effect on the vibration.  It demonstrated that B100, B5 and B20 have the lowest vibration.  On the contrary, B15 and B10 have the highest vibration.   Keywords: vibration analysis, power tiller, time domain, frequency domain, diesel-biodiesel fuel blend

CONTEMPORARY AND FUTURE DEVELOPMENT OF 3D PRINTING TECHNOLOGY IN THE FIELD OF ASSISTIVE TECHNOLOGY, ORTHOTICS AND PROSTHETICS

3D printing is considered as a helpful technology that facilitates innovative assistive technology, orthotics, and prosthetics development. This technology could likely contribute to positive treatment outcomes. It could also mitigate the challenges encountered when using the traditional methods. Our team’s research in the application of 3D printing in prosthetics, orthotics and biomedical technology has shown beneficial results in its use. This article gives a general description on application of CAD/CAM, digitalization and 3d printing in this industry followed by short description of two spinal-related projects conducted in our research team. Technological and clinical challenges on utilization of this technology have been listed. Finally, this manuscript provides recommendation for broader applications and developments of the aforementioned technology through interdisciplinary practices. A glimpse into the future of 3D printing in the healthcare industry shows that this industry is poised to continue having a significant impact in this sector. It should be emphasized that assistive technology, orthotics, and prosthetics require a human touch and connection, and no digital tool or technology can replace such requirements. Indeed, multi-disciplinary collaboration is the key to the success of applications of 3D printing. Article PDF Link: https://jps.library.utoronto.ca/index.php/cpoj/article/view/42225/32491 How To Cite: Hassan Beygi B, Wong M.S. Contemporary and future development of 3D printing technology in the field of assistive technology, orthotics and prosthetics. Canadian Prosthetics & Orthotics Journal. 2023; Volume 6, Issue 2, No.10. https://doi.org/10.33137/cpoj.v6i2.42225 Corresponding Author: M.S. WONG, PhD The Department of Biomedical Engineering, The Hong Kong Polytechnic University, Hong Kong. E-Mail: [email protected] ORCID ID: https://orcid.org/0000-0002-4157-952

Design, development and test of the gearbox condition monitoring system using sound signal processing

Introduction One of the ways used for minimizing the cost of maintenance and repairs of rotating industrial equipment is condition monitoring using acoustic analysis. One of the most important problems which always have been under consideration in industrial equipment application is confidence possibility. Each dynamic, electrical, hydraulic or thermal system has certain characteristics which show the normal condition of the machine during function. Any changes of the characteristics can be a signal of a problem in the machine. The aim of condition monitoring is system condition determination using measurements of the signals of characteristics and using this information for system impairment prognostication. There are a lot of ways for condition monitoring of different systems, but sound analysis is accepted and used extensively as a method for condition investigation of rotating machines. The aim of this research is the design and construction of considered gearbox and using of obtaining data in frequency and time spectrum in order to analyze the sound and diagnosis. Materials and Methods This research was conducted at the department of mechanical biosystem workshop at Aboureihan College at Tehran University in February 15th.2015. In this research, in order to investigate the trend of diagnosis and gearbox condition, a system was designed and then constructed. The sound of correct and damaged gearbox was investigated by audiometer and stored in computer for data analysis. Sound measurement was done in three pinions speed of 749, 1050 and 1496 rpm and for correct gearboxes, damage of the fracture of a tooth and a tooth wear. Gearbox design and construction: In order to conduct the research, a gearbox with simple gearwheels was designed according to current needs. Then mentioned gearbox and its accessories were modeled in CATIA V5-R20 software and then the system was constructed. Gearbox is a machine that is used for mechanical power transition from a productive source of power to a consumer, for torque meeting and for rotating speed needed for the consumer. In fact, gearbox is an interfere between power source and power consumer which produces a flexible communication between power source and power consumer. Needing to a gearbox as a machine which can generate harmony as an interface is unavoidable due to lack of harmony of torque and rotating speed of production source of power. So necessary calculations in order to attain to technical characteristics of gearwheels, bearings, shaft dimensions and other accessories of gearbox were done. This gearbox is from kinds of simple gearwheel which its input and output shaft are parallel to each other. Main accessories of gearbox are: 1.crust 2.shaft 3.gearwheel 4.thorn 5.bearing 6.cover. All of the design parameters were calculated and considered in designing of all of the accessories of gearbox. Electromotor rotating calibration: For this aim, a light-contact telemeter in model of Lutron was used as contact. Acoustic module of electro motor: A module was constructed in order to prevent from sound waves interaction resulting from an electromotor function with waves of gearbox function. Three layers of sound absorbent including common felt with 1mm width, polyethylene foam with 15 mm width and shoulder foam egg with 35 mm width were used for the module insulation. Material used for the body of this module was MDF. Based on field measurement, level of electromotor sound decrement using the acoustic module was 20dB. Investigated malfunctions in this research are relevant to gearwheel with one tooth fracture, one worn tooth and one tooth fracture and other worn tooth. Collection and storage of acoustic data: In this research, an audiometer in model of HT-157 made in Italy in order to obtain acoustic data and a laptop with a model of Lenovo-G550 for data storage and processing was used. Cool Edit Pro 2.0 software was used for data processing. Data storage was in PCM format and MATLAB R2014a software used for data processing. Data processing: Signal processing method in the frequency domain is used in order to reveal the defects. Fast Fourier Transform: Fast Fourier Transform FFT for application in electronic equipment specially analyzers have great importance. In this condition, sampling number is chosen exponentially as 2N which decreases the calculation volume significantly. Determination of defect kind of gearwheel using frequency spectrum analysis: In mentioned gearwheel, errors were generated synthetically. Defect kind of these errors was generated in separate gearwheels in order to investigate the defects more precisely and a gearwheel was considered as control gearwheel. Despite of this, the sound of all of the gearwheels in correct condition was stored. Results and Discussion Comparison of processed acoustic signals from gearwheels of gearbox in two correct and incorrect conditions was indicative of gearwheel involvement, frequency, their harmony and the changes resulted from defects. Gearwheel defect detection tests showed that at the speeds of 1496, 1050 and 749 rpm, investigated defects are recognizable with a comparison of the frequency spectrum of obtained signals in correct and incorrect conditions and according to the involvement frequency of gearwheel, its harmony and sided spectrum. Results of the frequency spectrum of signal analysis in speed of 1496 rpm pinion showed the defect of one tooth fracture in involvement frequency of gearwheels by 489, 350 and 249 Hz respectively which became apparent with a mentioned frequency domain increment. A worn tooth defect in a gearwheel was completely determinable as sided bands with equal distance around gearwheel involvement frequency in the signal frequency determination of the speeds of 1496 and 105 rpm pinion, but became a bit harder in less speeds. Investigation of frequency spectrum of acoustic signal resulted from gearwheel, is indicative of the ability of this method in gearbox condition investigation with high precision and minimum time. So the gearbox condition investigation is reached by investigation of the frequency spectrum of acoustic signal resulted from gearwheel. Conclusions In current research, acquisitive signals resulted from produced sound waves of constructed gearwheel were used for investigation and diagnosis. Recorded signal in time domain and processed frequency and exploited characteristics of signal in frequency domain for diagnosis were analyzed. Obtained results of this research can be summarized as follow: 1. Precision level in the diagnosis decreased by increasing in pinion speed. 2. There will be a decrement in gearwheel diagnosis after defects integration and signal behavior won’t be completely similar to the defect as individual. 3. Proper placement of audiometer is effective in diagnosis trend. 4. In frequency spectrum of obtained signals, particle velocity level is more efficient in diagnosis than the sound pressure level

The effect of acoustic system variables on sound signals of Melon varieties

Introduction Cucumis melo includes a wide range of varieties. The acoustic is production, transmission and energy received form medium vibrations. Acoustic or sonic tests applies for grading productions, ripening determination of fruit firmness and sorting of broken eggs and so on in agriculture. Currently these methods are generalized for measuring non-spherical fruits properties. The primary objective of the present research was to investigate the effect of acoustic system variables such as impact places, impactor material type, pendulum angle and sound level meter position on acoustics response of two different melon varieties, including Zard-Eyvanekey and Sousky-Sabz. These results can be useful for designing acoustic implements related to agricultural products. Materials and Methods This research was conducted on 65 samples of Zard-Eyvanekey and Sousky-Sabz varieties (export varieties). A laboratory recording system used to acquire the acoustic impulse information that was comprised a mechanical excitement mechanism (an impactor such as pendulum), sound level meter, a lap-top computer and software to control the experimental setup and to analyze its results (Cool Edit Pro 2.0 Software), and melon-bed. The impactor consists of diameter and long copper rod 3 mm and 256 mm, respectively. The ball mass was 72.13 gram. The acoustic signal was sensed by a sound level meter (SLM) type 2270 B&K company Denmark. The samples locate on soft cushion for keeping because this bed prevents vibration distortion and causes free vibration. We consider three measurements on equator or mid-section of each fruit (approximately 120 degree) for diminishing inherent diversity of sample shapes. The sound level meter was placed at a distance of 2-5 mm from the fruit surface. The effects of sound level meter, impactor ball and pendulum angle on sound signals were investigated. The effects of other parameters were analyzed by factorial test in randomized complete plot by three replications for each sample. The treatments were 36 and 65 melons of each variety were selected. Results and Discussion The average samples peaks were 10576 and 28663 at 90 and 180 degrees respect to impact place, respectively. Other factors such as impactor ball type (steel), impact angle (70 degrees) and variety type (Zard-Eyvanekey) were constant. The resonance frequency was 123.05 Hz for both SLM position. The averages of peak sound pressure level were 55.29 and 52.38 dB at 90 and 180 degrees positions, respectively. It concluded that the change of sound pressure meter (SLM) position of 90 to 180 degree caused to increase sound pressure level but had no effect on reach the time to peak and resonance frequency. The effect of impactor ball material and impact angle of pendulum on recording signals approximately resemble up and did not state here. The factor levels were sound level meter position respect to impact place (two levels), impactor ball material (three levels) and impact angle of pendulum (three levels). We found that effect of sound level meter position; ball material and impact angle variables on sound pressure level values and interaction effect of sound level meter impact angle on FFT magnitude was significant at 1% level in both varieties. None of the variables and interactions has effect on the resonance frequency in both varieties. It can be concluded from tables that resonance frequency was more suitable than sound pressure level and FFT magnitude in acoustic tests. The increment of angle caused to increase impact velocity because the length and mass of pendulum rod were constant. We can state the above conclusion about impact velocity (excitement velocity) too, e.g. the impact velocity (excitement velocity) had no effect on resonance frequency while it effected on sound pressure level and FFT magnitude. This conclusion coincides to others researchers. Conclusions The impactor ball, pendulum angle, sound level meter position and variety type factors did not showve significant effect on resonance frequency but they had significant effect on FFT magnitude and sound pressure meter. Because of the high pressure level and measurement easily, it was recommended the position 90 degrees of microphone respect to impact place for acoustics measurements. The maximum sound pressure levels were 54.43, 54.81 and 55.11dB for glass, steel and plastic, respectively. Other factors such as SLM position (180 degrees respect to impact), impact angle (70 degrees) and variety type (Zard-Eyvanekey) were constant. Because of receiving high pressure level from impact angle of 70 degrees respect to 20 and 45 degrees, it was recommended for acoustics measurements. It can be used the lower angles by considering the low background sound

Statistical evaluation of the effect of water percentage in water-diesel emulsion on the engine performance and exhaust emission parameters

This research presents the results of statistical significance tests for evaluating the main effect of water-diesel emulsion usage (containing 2%, 5%, 8% and 10% by vol.) and engine load on the engine performance and emission parameters. To exclude inevitable random errors of measurements, the mean values of measured data were compared using Duncan's multiple range tests (MRT). The decrease in heating value and increase in fuel density and viscosity were observed with increasing water content. Although the fuel pour point decreased with water presence, but it didn't depend to water percentage. The combustion of emulsions significantly decreased the engine power and torque at 1% probability level (P < 0.01) due to the reduction in the heating value of emulsions. The lowest brake specific fuel consumption (BSFC) was observed for E2. Generally higher brake thermal efficiency was found for emulsions due to more complete combustion. The significant decrease (P < 0.01) in combustion temperature for E5, E8 and E10, increased the engine CO and decreased its CO2. Emulsion usage decreased engine NOx through reducing combustion temperature when compared to neat diesel. As a whole, E5 with highest improvement in the engine HC, NOx and CO2 could be the best suggestion to decrease undesirable engine emission