Saturday, January 31, 2009
Friday, January 23, 2009
Belts --Weekly update
Belts
Highlights of the topic covered till 24.01.2009
1. Velocity ratio
2. Length of the belt : open belt drive, crossed belt drive
3. Ratio of tensions , flat belt, V belt , rope drive
4. Angle of lap should be in radians
5. value of Alpha varies for open and cross belt drive
6. Power transmitted = product of velocity and difference in tensions
7. centrifugal tension = mass X square of velocity of belt
8. Maximum tension = centrifugal tension + tight side tension
9. Conditions for maximum power
10. Initial tension
11. Derivation for length of belt for open and crossed belt drive
12. slip, creep , stresses in belts
Problems in finding the power transmitted
Steps:
1. Find out the tensions .T1.T2 ,Centrifugal tension ,Maximum tension
2. For finding these tensions you need to calculate the mass and velocity and the angle of lap
3. For finding the angle of lap you need to calculate the value of Alpha.
4. If mass is not given directly , find it out using the value of density and assume the length as 1m.
Refer the formulae chart and the assignment problems
Students are advised to submit the problems [ 1 to 10 ] before 30.01.2009 , [ 11
Highlights of the topic covered till 24.01.2009
1. Velocity ratio
2. Length of the belt : open belt drive, crossed belt drive
3. Ratio of tensions , flat belt, V belt , rope drive
4. Angle of lap should be in radians
5. value of Alpha varies for open and cross belt drive
6. Power transmitted = product of velocity and difference in tensions
7. centrifugal tension = mass X square of velocity of belt
8. Maximum tension = centrifugal tension + tight side tension
9. Conditions for maximum power
10. Initial tension
11. Derivation for length of belt for open and crossed belt drive
12. slip, creep , stresses in belts
Problems in finding the power transmitted
Steps:
1. Find out the tensions .T1.T2 ,Centrifugal tension ,Maximum tension
2. For finding these tensions you need to calculate the mass and velocity and the angle of lap
3. For finding the angle of lap you need to calculate the value of Alpha.
4. If mass is not given directly , find it out using the value of density and assume the length as 1m.
Refer the formulae chart and the assignment problems
Students are advised to submit the problems [ 1 to 10 ] before 30.01.2009 , [ 11
Sunday, January 18, 2009
Kinematics of Machines - belts
In order to facilitate the students, who missed my class and the students who need to have a quick review of the topics discussed, this initiative is taken.
• Belts – an introduction, materials used for belts
• Type of belting- open, crossed, compound, quarter belt drive etc
• Application of belts , direction of rotation
• Velocity ratio
• Criteria for selection of belts
• Simple problems related to velocity ratio
• Angle of lap, tension in belts[ tight side tension and slack side tension ],velocity of the belt
• Co efficient of friction, ratio of tension , power transmitted
• Power transmitted with respect to open and cross belt drive for the same speed criteria
• Relation among these parameters, respective equations was discussed.
• Simple problems in belts
Also download the material which is uploaded in rapidshare, in which you can find the basics of belts and simple problems
The link :
http://rapidshare.com/files/185303690/belt.pdf
• Belts – an introduction, materials used for belts
• Type of belting- open, crossed, compound, quarter belt drive etc
• Application of belts , direction of rotation
• Velocity ratio
• Criteria for selection of belts
• Simple problems related to velocity ratio
• Angle of lap, tension in belts[ tight side tension and slack side tension ],velocity of the belt
• Co efficient of friction, ratio of tension , power transmitted
• Power transmitted with respect to open and cross belt drive for the same speed criteria
• Relation among these parameters, respective equations was discussed.
• Simple problems in belts
Also download the material which is uploaded in rapidshare, in which you can find the basics of belts and simple problems
The link :
http://rapidshare.com/files/185303690/belt.pdf
Thursday, January 8, 2009
Mechanical Engineering: The Ever- Evolving—and Growing—Profession
by Avram Bar-Cohen
Three years have passed since an article called “Mechanical Engineering — The Ever-Evolving Profession” was published by Mechanical Engineering Online. As predicted, the mechanical engineering profession has indeed evolved since the article was published in August 2005. The marketplace, the profession, and the public at large have affirmed the critical role to be played by mechanical engineers in the 21st century.
In 2006, for instance, ME undergraduates supplanted electrical and computer engineering as the single largest group of engineering students in the United States. Mechanical engineering enrollment has increased by 25 percent since 1999, and in 2006 totaled approximately 80,288, 7 percent more than the electrical and computer engineering student population—the next largest group (Michael Gibbons, Databytes, Prism Magazine, January 2008). More than 16,000 ME undergraduate degrees were awarded in 2006.
In the annual U.S. News & World Report issue devoted to graduate engineering education, mechanical engineering was identified as the most popular engineering Ph.D. discipline and third among engineering master’s degrees. Moreover, the same issue quoted Edward Hensel, who heads the ME department at Rochester Institute of Technology, who said that “there’s a powerful pent-up demand in industry for mechanical engineers.” It also quoted Prof. Larry Silverberg, associate ME chair at North Carolina State University, who explained the relative abundance of research funding by noting that “… so many of the critical problems in the forefront now lie in the area of mechanical engineering.” (Thomas K. Grose, USN&WR, March 26, 2008).
Mechanical design and manufacturing, written off even by many MEs as hopelessly antiquated skill-sets, are playing a pivotal role in the development and commercialization of new products and systems in the U.S. Black & Decker’s powerful new family of cordless power tools was made possible by a Watertown, Mass., startup’s production ramp-up of novel lithium-ion batteries from a handful of units in late 2005 to millions per year in 2007. (Kevin Bullis, Technology Review, June 2008).
Mechanical gears—specifically, a hub-mounted epicyclic (planetary) gear system—underpin Pratt & Whitney’s recently introduced “game changing” Geared Turbo Fan jet engine, which dramatically reduces fuel consumption and noise. Low pressure-drop compact heat exchangers—yet another “classic” ME knowledge domain—are a key element in the high-efficiency Mercury 50 gas turbine manufactured by Solar Turbines. (Lee Langston, Mechanical Engineering, May 2008).
Against this background, the ASME-led Global Summit on the Future of Mechanical Engineering concluded that unique skills in system integration—across technologies and across time zones—will place mechanical engineers on the critical path for the development of a broad range of 21st-century products and systems (Harry Hutchinson, Mechanical Engineering, June 2008).
The recent sea-change in the perceptions of mechanical engineering validates and confirms our commitment to this profession. However, if the challenges posed by the reemergence of world-wide scarcity in energy, water, food, and shelter are to be met, along with the economic pressures confronting the U.S., the education of mechanical engineers and the structure of the ME profession in this country must be radically altered.
Nothing short of a concerted effort on the reprofessionalization of mechanical engineering, including transformative changes in engineering education at the undergraduate and graduate levels, in ASME’s interactions with the broader engineering community, and in the relationship between engineers and their employers will suffice.
Avram Bar-Cohen is Distinguished University Professor and chair of the Department of Mechanical Engineering at the University of Maryland.
Coutesy: http://memagazine.asme.org/
Three years have passed since an article called “Mechanical Engineering — The Ever-Evolving Profession” was published by Mechanical Engineering Online. As predicted, the mechanical engineering profession has indeed evolved since the article was published in August 2005. The marketplace, the profession, and the public at large have affirmed the critical role to be played by mechanical engineers in the 21st century.
In 2006, for instance, ME undergraduates supplanted electrical and computer engineering as the single largest group of engineering students in the United States. Mechanical engineering enrollment has increased by 25 percent since 1999, and in 2006 totaled approximately 80,288, 7 percent more than the electrical and computer engineering student population—the next largest group (Michael Gibbons, Databytes, Prism Magazine, January 2008). More than 16,000 ME undergraduate degrees were awarded in 2006.
In the annual U.S. News & World Report issue devoted to graduate engineering education, mechanical engineering was identified as the most popular engineering Ph.D. discipline and third among engineering master’s degrees. Moreover, the same issue quoted Edward Hensel, who heads the ME department at Rochester Institute of Technology, who said that “there’s a powerful pent-up demand in industry for mechanical engineers.” It also quoted Prof. Larry Silverberg, associate ME chair at North Carolina State University, who explained the relative abundance of research funding by noting that “… so many of the critical problems in the forefront now lie in the area of mechanical engineering.” (Thomas K. Grose, USN&WR, March 26, 2008).
Mechanical design and manufacturing, written off even by many MEs as hopelessly antiquated skill-sets, are playing a pivotal role in the development and commercialization of new products and systems in the U.S. Black & Decker’s powerful new family of cordless power tools was made possible by a Watertown, Mass., startup’s production ramp-up of novel lithium-ion batteries from a handful of units in late 2005 to millions per year in 2007. (Kevin Bullis, Technology Review, June 2008).
Mechanical gears—specifically, a hub-mounted epicyclic (planetary) gear system—underpin Pratt & Whitney’s recently introduced “game changing” Geared Turbo Fan jet engine, which dramatically reduces fuel consumption and noise. Low pressure-drop compact heat exchangers—yet another “classic” ME knowledge domain—are a key element in the high-efficiency Mercury 50 gas turbine manufactured by Solar Turbines. (Lee Langston, Mechanical Engineering, May 2008).
Against this background, the ASME-led Global Summit on the Future of Mechanical Engineering concluded that unique skills in system integration—across technologies and across time zones—will place mechanical engineers on the critical path for the development of a broad range of 21st-century products and systems (Harry Hutchinson, Mechanical Engineering, June 2008).
The recent sea-change in the perceptions of mechanical engineering validates and confirms our commitment to this profession. However, if the challenges posed by the reemergence of world-wide scarcity in energy, water, food, and shelter are to be met, along with the economic pressures confronting the U.S., the education of mechanical engineers and the structure of the ME profession in this country must be radically altered.
Nothing short of a concerted effort on the reprofessionalization of mechanical engineering, including transformative changes in engineering education at the undergraduate and graduate levels, in ASME’s interactions with the broader engineering community, and in the relationship between engineers and their employers will suffice.
Avram Bar-Cohen is Distinguished University Professor and chair of the Department of Mechanical Engineering at the University of Maryland.
Coutesy: http://memagazine.asme.org/
Friday, January 2, 2009
Viva for Engg practices lab-II
Part -II
1. How will you perform taper turning operation in the lathe?
2. How are air conditioners working?
3. What is a refrigerant?
4. What are the common refrigerants used?
5. Explain the functionality of centrifugal pumps.
6. What is a foundry?
7. What are patterns?
8. Explain Knurling operation on lathe.
9. What is smithy?
10. What is an impeller?
11. differentiate window air conditioning and centralized air conditioning
12. Differentiate facing and turning
13. What is a truss?
14. Explain feed and depth of cut with respect to lathe.
15. What is the name of the workholding device in the lathe , give its types.
1. How will you perform taper turning operation in the lathe?
2. How are air conditioners working?
3. What is a refrigerant?
4. What are the common refrigerants used?
5. Explain the functionality of centrifugal pumps.
6. What is a foundry?
7. What are patterns?
8. Explain Knurling operation on lathe.
9. What is smithy?
10. What is an impeller?
11. differentiate window air conditioning and centralized air conditioning
12. Differentiate facing and turning
13. What is a truss?
14. Explain feed and depth of cut with respect to lathe.
15. What is the name of the workholding device in the lathe , give its types.
Practical exam ......
- Each of the student need to perform 2 exercises for 100 marks
- The student has to go to Mech / civil lab and ECE or EEE lab
- first fifteen of the batch will go to the mech or civil lab which contains 15 exercises.
- civil lab means exercises in carpentry and plumbing ,mechanical lab contains lathe and welding . [ total exercises includes 15]
- After completion in the first 1.5 hours the student needs to go to the next lab which may be EEE or ECE [ Which contains 15 experiments] and the student needs to choose one.
- The weightage for each lab is 50 marks .
-For instance if the roll no. of the student in Batch -I is XX006 he falls under the first fifteen and need to go to mech/civil lab, for the first exercise after completion ,he need to go to the EEE /ECE lab.
- If the student roll no. is XX038 the first exercise is in EEE/ECE lab and the second exercise is in mech/civil lab.
-Students are therefore advised to come early to identify the batch and the lab
-Students without uniform /lab coat ,shoes will not be permitted for the exams
- observation and record need to be submitted during the examination
- viva voce has a proportionate weightage. hence advised to prepare for the same
[ refer my earlier posts for FAQs in viva ]
All the best my dear students...
Subramanian.N. ,Senior Lecturer
- The student has to go to Mech / civil lab and ECE or EEE lab
- first fifteen of the batch will go to the mech or civil lab which contains 15 exercises.
- civil lab means exercises in carpentry and plumbing ,mechanical lab contains lathe and welding . [ total exercises includes 15]
- After completion in the first 1.5 hours the student needs to go to the next lab which may be EEE or ECE [ Which contains 15 experiments] and the student needs to choose one.
- The weightage for each lab is 50 marks .
-For instance if the roll no. of the student in Batch -I is XX006 he falls under the first fifteen and need to go to mech/civil lab, for the first exercise after completion ,he need to go to the EEE /ECE lab.
- If the student roll no. is XX038 the first exercise is in EEE/ECE lab and the second exercise is in mech/civil lab.
-Students are therefore advised to come early to identify the batch and the lab
-Students without uniform /lab coat ,shoes will not be permitted for the exams
- observation and record need to be submitted during the examination
- viva voce has a proportionate weightage. hence advised to prepare for the same
[ refer my earlier posts for FAQs in viva ]
All the best my dear students...
Subramanian.N. ,Senior Lecturer
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