design of an affordable model laboratory for mechanical ... · design of an affordable model...

Proceedings of the 2003 American Society for Engineering Education Annual Conference & ExpositionCopyright © 2003, American Society for Engineering Education

Session 1526

DESIGN OF AN AFFORDABLE MODEL LABORATORYFOR

MECHANICAL AND CIVIL ENGINEERING PROGRAMS

Bijan Sepahpour

The College of New JerseyDepartment of Engineering

Ewing, New Jersey 08628-0718609. 771. 3463

[email protected]

Laboratory experimentation is a critical final link for a thorough understanding of scientific andengineering theories. Development of the laboratory components plays a significant role in theenhancement and completeness of the engineering courses and programs. Twelve experimentsare presented for adaptation in undergraduate mechanical and civil engineering programs. Theseexperiments are related to topics in mechanics of materials and dynamics of machinery.Enthusiastic undergraduate students have been participating in the processes of research, designand development necessary for materializing all components of the Model Laboratory. Theirunderstanding of group dynamics and appreciation for cost-effective and superior designs hasenhanced. A comprehensive and user-friendly web site is constructed to provide all necessaryinformation for fabrication and application of these experiments and their associated apparatuses.This includes the outline of the experiments, the required equipment and time, complete set ofblueprints, detailed parts list, reliable sources, cost analysis, and degree of difficulty and the timeinvolved in machining and fabrication for each of the experiments. The cost-effectiveness,diversity, and high caliber of the proposed experiments make them suitable for use in themajority of undergraduate programs nationwide. As a package, they may lay the foundation fora starting laboratory course or selectively, each may be added to the existing archives ofexperiments at many undergraduate engineering programs.

I - INTRODUCTION

Laboratory experimentation is a critical final link for a thorough understanding of scientific andengineering theories. Every possible effort should be made not to deprive the future engineers oreducators from this vital component of their education. Many colleagues involved in theteaching and conducting of laboratory courses subscribe to this ancient Chinese proverb:

"When I hear, I forget; When I see, I remember; and When I do, I understand."

This paper describes the parameters involved in generation of an exemplary and yet affordableundergraduate laboratory designed for conducting experiments in Mechanics of Materials andDynamics of Machinery. The central role of the undergraduate students and the instrumentalrole of the coordinator in achieving this task are discussed.


Twelve (12) experiments and fifteen (15) associated apparatuses are nearly completed under thisplan. A full information package is generated for national dissemination through a web-site. Asa package, they may lay the foundation for a starting laboratory course or selectively, each maybe added to the existing archives of experiments at many undergraduate engineering programs.

Enthusiastic undergraduate students have been participating in the implementation processes ofresearch, design and development necessary for materializing all components of the ModelLaboratory. Their understanding of group dynamics and appreciation for cost-effective andsuperior designs has been enhanced.

Partial support of NSF, which started in January of 2002 has increased the momentum of theefforts that have started since 1998 for creation of the State of the Art Laboratory. Successfulimplementation of this project has resulted in several measurable outcomes as:

1. Generation of comprehensive blueprints for fabrication of apparatuses necessary forprecision experimentation in the areas of Mechanics of Materials and Dynamics ofMachinery.

2. Creation of detailed laboratory manuals-ready for distribution to students.

3. A well thought out and comprehensive plan for putting together an affordable modellaboratory that successfully addresses the fundamental requirements of undergraduatelaboratories in mechanical and civil engineering as well as engineering technology programs.

4. Enhancement of capabilities of future engineers/educators by their involvement in theprocesses of research, design and development and group dynamics.

5. Creation of a National Data Bank for submission and distribution of all informationnecessary for putting together an affordable model laboratory that may successfully addressthe fundamental requirements of undergraduate experimentation in mechanics of materialsand dynamics of machinery.

Collaboration with other colleagues may further enhance the quality of the proposed modellaboratory, which may then be considered for adaptation and implementation at national scale.

II � THE PROBLEM AND A POTENTIAL SOLUTION

Laboratory apparatus is generally expensive due to low production levels and specializedfeatures. Further, for larger class sizes; to avoid demonstration (rather than experimentation),multiple numbers of the same apparatus are usually required for controlling time constraints.One of the major contributing factors in making engineering programs expensive is the cost ofthe apparatus and equipment required for experimentation. These factors may pose somesignificant difficulties for low-budget programs in terms of justification of their cost.Consequently, students may be deprived from being sufficiently exposed to important conceptssuch as verification of the theory through experimentation, interpretation and analysis of data andgaining sufficient background for designing experiments.


The necessary and sufficient conditions for creating meaningful laboratory components ofengineering courses and programs may be described as:

1. Availability of laboratory coordinators with high levels of dedication, enthusiasm andknow-how,

2. Availability of the required space,3. Availability of the apparatus and equipment required for conducting experiments.

Assuming that the first two of these conditions are in place, strategies for satisfying the lastcondition must be developed. To populate the available space with the minimum requiredapparatus and equipment, the cost factors must be brought under control.

Computer software and hardware prices are continuously dropping; making the majoringredients of the necessary laboratory equipment attractively affordable. Unfortunately, such isnot the case for the required apparatus. Even for non-profit organizations; materials,components and machining costs are unavoidable. The high cost of such products may beexplained by the following two main factors:

1. The limited number of orders, 2. Significantly higher Design Costs built into the final cost.

However, if blueprints of the designs of the apparatuses are available, a major cut may beexpected in the final cost. Such designs and blueprints may be generated in-house incollaboration with undergraduate students. Prototypes of such units may be constructed andtested to ensure the high quality and reliability of the suggested designs. Potential fabrication ofthe tested designs may also be conceived at the facilities of such programs. Enthusiasticengineering students, the machinists and technicians of the department may collaborate with thecoordinator in achieving such a task.

Comprehensive blueprints of the designs along with their corresponding laboratory manuals maybe distributed to all engineering programs. Engineering faculty at other institutions may consideradopting this model and joining forces to create a large "Data Bank" for compilation of theresults of their valuable efforts.

To implement such a model, in September of 1997, the author proposed to the administration ofThe College of New Jersey (TCNJ) a two-phase plan for creation of the State of the ArtLaboratories for the Mechanical Engineering Specialty of the engineering programs. Phase one,targeting the generation of the apparatuses required for conducting precision experimentation inthe area of Mechanics of Materials and phase two focusing on the design and fabrication of theapparatuses for experiments in the area of Dynamics of Machinery. This activity wouldofficially start in September of 1998 and spread over a period of four years; each phase takingabout two-three years.

The proposal was approved and TCNJ has provided support on a continuous base since theinception of the project. Further, National Science Foundation (NSF) provided additionalsupport since January of 2002 which has increased the level of activity in the project and hasadded momentum to it.


III - INVOLVING STUDENTS

"Introductory courses for all students should offer a serious encounter with both the process andessential concepts of mathematics, science, engineering, and technology. The course should beproblem driven, emphasize critical thinking, have hands-on experiences, and be taught in thecontext of topics that students confront in their own lives� ." [1]

Engineering students at TCNJ take their first Mechanical Laboratory course simultaneously withthe Mechanics of Materials course in the second semester of their sophomore year. Students, ingroups of three to four, are charged with the task of designing an experiment that examines thevalidity of a physical law/engineering principle/formula or a technique/approach that measures acertain quantity. This requirement is carefully matched with the theoretical content of the twointerdependent courses.

In this process, the coordinator will be able to discover groups/students with high level of interestand enthusiasm. Some of these proposed experiments may be expanded/fine tuned intomeaningful and affordable entities. Alternatively, the coordinator may discover the need for acertain experiment, define the problem for a group of interested students/class and collaboratewith them in the brainstorming, prototyping, testing and conceiving the final unit. This trendmay continue through the second, third and the final laboratory course. In exceptional cases, thecontinued efforts of the student(s) may be justifiable for credits towards an independent studycourse or even a senior design project.

Incorporation of design all through an engineering curriculum provides opportunities for youngengineers to recognize their full potential and increase their confidence level significantly. Thus,they would be better prepared to meet the most critical demands of today�s industry. [2]

The proposed model and approach would provide opportunities for undergraduate students toget involved in the process of design and development of the apparatuses required for theplanned experiments. This would be a process through which the serious students may develop amuch deeper appreciation of the subject matter as well as the design and development process ina realistic environment. Equally important, it would enhance their chances for receivingResearch/Teaching Assistantship or Full Scholarships in graduate engineering programs. Severalcase studies (shown later) reflect on the promising nature of this approach/model.

IV� DESIGN OF THE EXPERIMENTS AND THEIR ASSOCIATED APPARATUSES

"Everything must be made as simple as possible, but not simpler." (Albert Einstein)The following criteria have been incorporated in the design of the experiments and the associatedapparatuses:

• Safety • Simplicity and Practicality in Fabrication• Affordability/ Control of Cost • Use of Reliable Sources for Components• Durability • Use of Non-Corrosive & Aesthetically Pleasing Materials• Simplicity of Operation • NO use of Discontinued Parts/Components• Time Factor in the Experiment • Application of Software for Initial Prototyping


Table (1) provides a listing of the parameters involved in the successful implementation of theproject.

# Type of Activity1 Brainstorming and Design of the Experiments and the Apparatuses2 Meeting Minutes and Progress Reports for Each Experiment3 Prototyping4 Generation of Technical Drawings for each of the Apparatuses5 Selection of Components and Identification of Suitable Sources6 Fabrication and Compilation of Notes on Best Approach for Machining7 Instrumentation and Interfacing8 Testing, Calibration, Generation of Data and Measure of Accuracy9 Generation and Finalizing Laboratory Manual for Each Experiment

10 Loading of All Necessary Information and Helpful Links on the Web Site

Table 1: Parameters involved in the successful implementation of the project.

Table (2) shows the current status of the listed experiments in terms of their:• Design,• Material and Component Cost per One Unit and per 2 Units,• Required Fabrication Time and Degree of Difficulty.

Upon completion of the design, fabrication and full testing of each of these proposedexperiments, a full information package is generated and loaded on a web-site for nationaldissemination. The cost-effectiveness, diversity, and high caliber of the proposed experimentsmake them suitable for use in the majority of undergraduate programs nationwide. As a package,they may lay the foundation for a starting laboratory course or selectively, each may be added tothe existing archives of experiments at many undergraduate engineering programs.

A condensed description of each of the twelve (12) experiments and the associated fifteen (15)apparatuses (listed in Table 2), is presented in "Appendix B." This package provides additionalinformation on:

• Equipment Requirement• Fabrication Requirement

• Optional Interface with LabVIEW


#EXPERIMENT

/APPARATUS

DEGREE OFDIFFICULTYIN DESIGN(SCALE OF

1 � 10 )

DESIGNSTATUS

COST OFMATERIAL

ANDCOMPON.PER UNIT

RECOMM-ENDED

QUANTITY

FABRICATION& ASSEMBLYTIME /1 UNIT

FABRICATION& ASSEMBLYTIME/2 UNITS

DEGREE OFDIFFICULTYIN FABRIC.(SCALE OF

1 � 10 )

1 UNIVERSAL FRAME

7 95 %* $ 950 2 3 5 3

2 UNIVERSAL SUPPORTS

5 95 %* $100 / SET 2 SETS 18 30 5

3HIGH MECH. ADV. LOADER

8 95 %* $ 350 2 25 40 6

4 DATA ANALYSIS

8 95 %* $ 80 1 SET NA NA NA

5 MOMENT OF INERTIA

7 95 %* $ 200 1 SET 8 NA 3

6DEFORM. OFNON-PRISMAT. BARS

7 ½ 95 %* $ 350 2 12 20 5

7 COMBINED STRESSES

9 ½ 95 %* $ 2700 ONE 120 NA 8

8STRESSES IN A TRUSS FRAME

8 ½ 85 % $ 1050 2 30 50 8

9 STRESSES INAN I�BEAM

7 85 % $ 700 2 20 35 6

10THIN-WALLED PRESSURE VESSEL

7 ½ 80 % $ 1550 2 50 70 8

11 BUCKLING OF COLUMNS

9 90 % $ 450 2 30 48 7

12EXCEPTIONAL LOADS IN DEFLECTION

8 95 %* $ 750 ONE SET 50 NA 7

13 IMPENDING MOTION

5 95 %* $ 300 2 35 55 6

14 DIFFERENTIAL PULLEYS

8 90 % $ 950 ONE SET 35 NA 7

15MECH. ADV. &MOTION OFGEAR TRAINS

9 ½ 90 % $ 2100 2 50 85 8

TABLE 2: The Proposed Experiments/Apparatuses.( * = The remaining 5 % is reserved for ongoing potential optimizations, additions and minor changes)


V - CASE STUDIES

1. Universal Combined Stress Apparatus (UCSA) and an Example of Team Work

While most commercially available apparatuses provide data for a single type of load, no sucheducational apparatus for generation of Simultaneous Combined Stresses existed. Creation ofsuch an apparatus would be a remarkable addition to the engineering laboratories at anyinstitution.This unique apparatus and experiment is designed to investigate the state of stresses in combinedloading scenarios. Eight (8) Rectangular Rosette Strain Gauges are strategically installed on twodifferent sections of the specimen (6061-T6 Aluminum Tubing with 1/8" wall, 3.75" O.D. and42" Length/Height) to generate 24 strain readings leading to the values of the correspondingeight (8) Principal Stresses ( σ1 , σ2 ) and Maximum Shear Stresses ( τ max. ). Specifically, it isdesigned for:

1. Generation of Incremental Precision Torque for application of pure torque,2. Generation of Incremental Bending Moment in the X-Y plane,3. Generation of Incremental Bending Moment in the Z-Y plane,

4. Any Combination of the Loads available in steps 1, 2, and 3 resulting in a Combined Loading / Stress Situation.

Three engineering students (Kevin Olesky, Carl Janetti and Patrick Carroll) collaborated withthe coordinator in nearly all phases of the project; Design and Fabrication of the "UCSA."These three students got fully exposed to the entire spectrum of the project - from First Draft tothe Final Production and Comprehensive Testing of the device. They started their involvementin the spring of 1998 and continued until the end of the summer of 1999. Their high level ofenthusiasm, dedication and voluntary-based contributions was rewarded by the Department�sService Award in May of 1999. The two laboratory assistants, Daniel Snyder and MichaelMancino and another volunteer student, Jenny Castellano provided additional support in theprocesses of brainstorming, design, modeling, fabrication, instrumentation, data collection andcomputer programming. Alexander Michalchuk, the department machinist, provided guidance inthe fabrication process and performed machining on the more demanding components. Thecoordinator took over the task of installing the Rosette gauges on the non-flat surface of thespecimen. Michael Mensch, the department technician, provided assistance in the fine solderingof the electrical network.

The tested apparatus consistently returns results with a high level of accuracy and precision whencompared to expected theoretical values. The commercial cost of such an apparatus (should itbe available) is estimated to be well over $30,000. Total cost of the materials and componentswere kept well under $3,000. Of course, the time factor involved in machining and installationof the gauges should not be overlooked. Appendix: A-1, contains photographs of the completed�Universal Combined stress apparatus (UCSA).� Appendix: A-2 contains samples of stress datagenerated using the �UCSA� for 8 stress elements during different loading scenarios.


2. Stresses in a Truss Frame

This experiment enables the undergraduate students to measure the stresses and forces indifferent members of a truss frame / bridge. Linear strain gauges are installed at criticallocations of the apparatus. Both symmetric and non-symmetric loads are applied to the unit. Asecond unit (in the upside � down configuration) may be examined by a different group ofstudents simultaneously.

Design and manufacturing of this unit has posed many interesting challenges. The firstprototype suffered from the buckling effect. The initial design was primarily dominated by thefollowing two criteria. First, the thickness of the section was chosen based on the assumptionthat a maximum load of 30 lb. may be applied to the unit using only conventional methods ofapplication of loads. Second, to establish reliable values of the corresponding stresses andforces, the cross sections of the Truss Members must be chosen such that they experiencemeaningful and appreciable levels of strain. This valuable failure lesson encouraged both thecoordinator and the collaborating students to design a High Mechanical Advantage Loader(HMAL) to lift the first constraint of the initial design while maintaining or potentiallyimproving on the second constraint.

With the birth of HMAL�200 (described in Appendix D), a second prototype was attempted withthe necessary modifications and improvements. The Truss Frame is successfully designed andconstructed. The unit displays appreciable deformations under several loading scenarios. Theexperience gained in this process has been quite valuable both for the Coordinator and thecollaborating student designers. Design and manufacture of another experiment and apparatus -"Stresses in an I�Beam," has benefited substantially from the valuable lessons learned in thisexercise.

A photograph of the unit is placed in Appendix: B. This Photograph also displays theingeniously designed HMAL that may easily be manufactured by an average machinist. In thiscase, it was machined by the students under the supervision of the coordinator. This unit maysafely apply loads up to 300 lbs. to many other specimens.

Two entirely different groups of students were involved in two different semesters. While thesecond group built on the work of the first and nearly completed the task, it was truly the first(presumably failing group) that contributed to the major goals of the task.

3. Springs and their Applications in Design of Experiments

This outstanding experiment was designed in collaboration with sophomore engineering studentsin Mech. Lab. I. The main idea was to utilize springs in verification of the deformation of Non-Prismatic Bars. More importantly, the designing students, their classmates (and future peers)come to realize that "it is quite possible to utilize simple components in design of experimentsthat may verify and visualize a relatively difficult theory." The laboratory handout for thisaffordable experiment is placed in "Appendix C."


Figure 1. First Group of the Collaborating Students in the Inception of the "Affordable Model Laboratory."

VI - THE WEB-SITE

A comprehensive and user-friendly Web Site is under construction. This site is intended toprovide complete information for construction and application of all of the experiments and theirassociated apparatuses. This includes complete set of blueprints, detailed parts list, reliablesources, cost analysis, and degree of difficulty and the time involved in machining for each of theexperiments.

The PI and one of the dedicated students (Elton Clark) have started the preliminary design andloading of the Web Site. The College of New Jersey (TCNJ) has granted permission to createthis site on the server of the college.

The Site is compatible with Internet Explorer browser, which is included in any windowsoperating system. At this time, the Site may be accessed through the following temporaryname:

Case - SensitiveAuto-Cad does not support Netscape

http://www.tcnj.edu/~clark2/NSF/


VII � THE ROLE OF THE ADVISOR

The role of the coordinator in the success of each of the collaborating groups of students isinstrumental. Table (3) provides some suggested strategies that the author has found helpful inincreasing the chances of success for such teams and projects. [3]

VIII� TWO AREAS OF CONCERN

For the proposed experiments in the current package, there are two areas they may beproblematic; the problem of in-house machining and installation of the strain gauges.

Measurement Group Inc. provides free of charge one-week educational programs for trainingeducators in Applications of Strain Measuring Systems in Stress Analysis. They have alsocreated educational videotapes designed for installation of gauges at a nominal charge of $ 100.

For the machining issue, there are many feasible alternatives where there are no on sitetechnicians/machinists or students who can accomplish the task. Alternatively, if there is hardlyany possibilities for machining; the Web-Site still provides all of the necessary blueprints thatmay be taken to a machine shop for production. The average hourly rate for fabrication of theunits can not possibly exceed $50/hour. A careful calculation of the (conservatively) estimatednumber of required hours for machining (using data in Tables 1) results in estimates that makesthe package still quite an attractive and affordable one when compared to the commerciallyoffered units.

Certainly, laboratory coordinators must be willing to control the logistical problems of thisapproach. Should the grant move on to the upper phases, an article or a short regional workshopmay assist the willing coordinators to better control these parameters and develop their owneffective strategies relative to their individual environment.

IX� THE BENEFICIARIES

It goes without saying that the immediate beneficiaries of the project are the engineering studentsat The College of New Jersey (TCNJ). On average, 100-112 students (in concurrent sessionswith no more than 14 students) take the Mechanical Laboratory - I, II, III and IV coursesannually. All of these students will directly benefit from this project.

The availability of the Web Site, for obtaining comprehensive information on all of theexperiments makes it completely possible to incorporate these experiments and apparatuses inany engineering program with some effort and dedication on the part of the coordinators. It isestimated that hundreds of colleagues and thousands of students (nationwide) will benefit fromthis project annually.


Planning the Activity/Experiment

1. Evaluate the feasibility of conducting the project with regard to its required finances, human resources,equipment, facilities, etc.

2. Recruit members that their interpersonal and intellectual skills complement each other/have potential for growth.

3. Set realistic expectations and challenge the teams at levels that they may succeed.

4. Prepare a preliminary timetable for major activities involved in the project.

Conducting the Project

1. Plan a comprehensive first meeting, reviewing all objectives and logistical issues related to the project.

2. Review the role of each member as an individual contributor and make it clear that the success of the teamdepends on the performance and dedication level of each of the members.

3. Provide sources of information for conducting research and obtaining related literature.

4. Inform the new team about the existing network of support for obtaining financial and professional assistance.

5. Discuss the synergistic nature of the design and team work activity and provide examples of success and failureusing prior experiences, etc.

6. Set up a regular weekly time for group meetings that is compatible with every member's schedule and emphasizeon the importance of participation of all members.

7. Make them aware that a later change of design in one of the components/subsystems of the product may create a"Domino Effect" on many other components/subsystems.

8. Have all members provide a progress report on weekly-basis and discuss/brainstorm the potential solutions forthe newly encountered/unforeseen problems.

9. Encourage members to finalize a (seemingly) flawless and promising design before they start fabrication.

10. Encourage/require the team to test the functionality/practicality of their proposed designs by computersimulations and actual prototyping.

11. Establish ample hours for the project, and make yourself available for all team members.

12. Projects may be rolled over to the next group to continue the work or revisited at future laboratory courses.

13. Accept the fact that many students may have better solutions than yours.

14. Consider failures as the price for future success.

15. Establish a rewarding and appreciation system for all the parties involved.

Table 3. Suggestions for Improving the Chances of Success for Lab Generation Teams.


X - OUTCOMES AND CLOSURE

A promising model for design of an affordable and model laboratory for undergraduatemechanical and civil engineering programs has been proposed. Twelve experiments and theirassociated fifteen apparatuses are presented for adaptation in undergraduate mechanical and civilengineering programs. These experiments are related to topics in mechanics of materials anddynamics of machinery. Enthusiastic undergraduate students have been participating in theprocesses of research, design and development necessary for materializing all components of themodel laboratory. Their understanding of group dynamics and appreciation for cost-effectiveand superior designs has enhanced. A comprehensive and user-friendly web site is constructedto provide all necessary information for fabrication and application of these experiments andtheir associated apparatuses. This includes the outline of the experiments, the required equipmentand time, complete set of blueprints, detailed parts list, reliable sources, cost analysis, and degreeof difficulty and the time involved in machining and fabrication for each of the proposedexperiments. The cost-effectiveness, diversity, and high caliber of these experiments make themsuitable for use in the majority of undergraduate programs nationwide. As a package, they maylay the foundation for a starting laboratory course or selectively, each may be added to theexisting archives of experiments at many undergraduate engineering programs. Collaborationwith other colleagues may further enhance the quality of the proposed model laboratory, whichmay then be considered for adaptation and implementation at national scale.

ACKNOWLEGMENTS

The author wishes to thank all of the students who have made significant contributions to thesuccess of this project. He also wishes to thank Alexander Michalchuk and Michael Mensch fortheir continuous support and dedication to the project. He thanks the continuous support of TheCollege of New Jersey for implementing the rigorous tasks of this project. He also thanks NSFfor its support in adding momentum to the progress of the project by awarding grant # DUE-0127753.

REFERENCES

1. Zydney, et al. 2002. Impact of Undergraduate Research Experience in Engineering . Journal of Engineering Education. 91(2): 151-157.

2. Miller, J. W. / Sepahpour, B., "Design in the Engineering Curriculum", Proceedings of A.S.E.E. 1995 NationalConference, Anaheim, CA, July 1995, Vol. 1 (1995), Pg.: 2591-2596.

3. Sepahpour, B., �Involving Undergraduate Students in Design of an Affordable Model Laboratory�, Proceedings of ASEE 2002 National Conference, Montreal, Canada, June 2002.


BIJAN SEPAHPOURBijan Sepahpour is an Associate Professor of Mechanical Engineering at The College of New Jersey. He is activelyinvolved in the generation of design-oriented exercises and development of laboratory apparatus and experiments inthe areas of mechanics of materials and dynamics of machinery for undergraduate engineering programs. ProfessorSepahpour is an active member of ASME and ASEE. He has degrees from The College of New Jersey and NewJersey Institute of Technology.

APPENDICES

APPENDIX: A-1Photographs of the completed �Universal Combined Stress Apparatus.�

APPENDIX: A-2Samples of Stress Data generated using the "Universal Combined Stress Apparatus"during different loading scenarios.

APPENDIX: BCondensed Description of the Proposed Twelve (12) Experiments and their AssociatedFifteen (15) Apparatuses.

APPENDIX: CA preliminary Laboratory handout for the Experiment of "Deformation of Non-PrismaticBars".


APPENDIX: A-1Photographs of the completed �Universal Combined Stress Apparatus.�

APPENDIX: BCondensed Description of the Proposed Experiments and their Associated Apparatuses.

NOTE: In the "Fabrication Requirements" Boxes, an Average machinist is capable of working with the Lathe and Milling Machines. Using Hourly Rate as a benchmark, such a machinist is estimated to be paid about $20 - $25 per hour. The Hourly rate of an ABOVE Average machinist is estimated to be about $35 - $45.


1. Universal Frame (UF - 400)

A multi-purpose frame designed based on commercially available extruded aluminum with specific sections to support the

components of the apparatuses listed as #s: 6, 8, 9, 11, 15 (and more). The load capacity of the unit is 400 lb. with a factor of

safety of 2.2 (in quasi-static mode). Design and the modularity of the frame provide opportunities to run several experiments

simultaneously. The photograph on the right displays the possibility of running three different experiments at the same time.

Fabrication Requirements: NONE

Assembly REQUIRED.


2. Universal Supports (US � 300)

A set of supports for simulation of simply supported (with rollers on either end) as well as fixed/clamped ends used in

conjunction with the apparatuses listed as #s: 8, 9, 11 (and more). The load capacity of each support is over 300 lb. with a factor

of safety of 2.5 (in quasi-static mode) and may be located at any location of the vertical or horizontal members of UF � 400.

Fabrication Requirements: Average Machining Skills

-------------------------------------------------------------------------------------------------------------------------------------------------

3. High Mechanical Advantage Loader (HMAL � 200)

This system may generate different symmetric and non-symmetric point loads in applications where required magnitude of load

is considerably high. The loader may apply in excess of 200 lb. by two 10-lb. loads (one at each end). The flexibility in design of

the unit allows for adjustment of height and locations of the applied loads. Safety has been the primary consideration in the

design of this unit. Accidental drop of a 10 lb. load is considerably less catastrophic than drop of a 100 lb. load. If necessary /

desired, the unit can generate up to 300 lb. with a factor of safety of 1.95 (in quasi-static mode). HMAL � 200 is required for the

loading of the units listed as # 8, 9 and 11.



4. Data Analysis

An experiment designed for sophomores to comprehensively review the basic statistical tools used in analysis of data. This

review covers: (1) Histograms, (2) Population and Sample Mean, (3) Variance and Std. Deviation, (4) Probability, (5) Central

Tendency, (6) Error, (7) Minimum Required Number of Samples, and (8) Reliability

Fabrication Requirements: NONE

5. Moment of Inertia

This experiment allows the students to make appropriate selection and use of Linear Measurement tools to obtain the Area

Moment of Inertia of several (sets) of Round, Rectangular and S/W shapes sections and COMPARE the Strength to Weight

Ratios in each of the sets. Upon arriving at the values of these Ratios, they will discuss and justify their recommend choices in

different applications.

Mass Moment of Inertia of a commercially available pulley is next examined. A comparison of Manually calculated results is

made with the Pro-Engineer generated ones. Students are challenged to provide alternative approaches for obtaining the mass

moment of inertia of such shapes.

Tools required:1. Dial Calipers (4) 3. Micrometers (4)2. Linear Scales (4) 4. Weight / Mass Scales (2)



6. Deformation of Non-Prismatic Bars

An experiment designed to utilize Tension Springs for examining the role of each of the parameters involved in the equation:

∆ = δ = Σ ( Fi Li / Ai Ei ) used for obtaining the Elongation of both Prismatic and Non-Prismatic Bars. This exercise also

serves as an example (for students) to observe how they may utilize simple tools to create meaningful and yet conceivable

experiments.


A copy of the HANDOUT for this Experiment is placed in Appendix: C.


7. Combined Stresses

This unique (and NOT commercially available) apparatus and experiment is designed to investigate the state of stress in

combined loading scenarios. Eight Rectangular Rosette Strain Gauges are strategically installed on two different sections of the

specimen (6061-T6 Aluminum Tubing with 1/8" wall, 3.75" O.D. and 42" Length) to generate 24 strain readings leading to the

values of the corresponding eight (8) Principal Stresses ( σ1 , σ2 ) and 8 Maximum Shear Stresses ( τ max. ). Specifically, it is

designed for:

1. Generation of Incremental Precision Torque for application of pure torque,

2. Generation of Incremental Bending Moment in the X-Y plane,

3. Generation of Incremental Bending Moment in the Z-Y plane,

4. Any Combination of the Loads available in steps 1, 2, and 3 resulting in a

Combined Loading / Stress Situation.


Equipment requirements:

1. Three (preferably Four) Strain Indicators (such as Micro Measurement�s P-3500) or Equivalent

2. Three (preferably Four) Multi-port Switch and Balance Units (such as Micro Measurement�s SB-10)

Fabrication Requirements: Above Average Machining Skills

Ability to Install Strain Gauges

Optional: Possible Interface with LabVIEW

---------------------------------------------------------------------------------------------------------------------------------

8. Stresses in a Truss FrameThis experiment enables the undergraduate students to measure the stresses and forces in different members of a truss

frame / bridge. Linear strain gauges are installed at critical locations. HMAL � 200 is utilized to apply symmetric and non-

symmetric loads on the unit. A second unit (in the upside � down configuration) may be examined by a different group of

students simultaneously.


1. (UF - 400) or Equivalent

2. (US - 300) or Equivalent

3. HMAL � 200 or Equivalent

4. One Strain Indicator (such as Micro Measurement�s P-3500) or Equivalent

5. One Multi-port Switch and Balance Unit (such as Micro Measurement�s SB-10)





9. Stresses in an I � Beam

This experiment is designed to examine stresses at different locations (of span and section) of an I-beam. Rosette strain gauges

may be installed at interesting and critical locations of the beam. Several loading scenarios may be applied (using HMAL � 200)

to fully examine the signatures of stresses. To obtain appreciable and meaningful strain levels, and control the buckling effect,

the design of the I-beam calls for specific selection of materials and section properties.




3. HMAL � 200 or Equivalent

4. Two Strain Indicators (such as Micro Measurement�s P-3500) or Equivalent

5. Two Multi-port Switch and Balance Units (such as Micro Measurement�s SB-10)





10. Thin-Walled Pressure Vessel

This experiment will enable the student to investigate the validity of the basic equations of stress in Thin-Walled Pressure

Vessels. An added feature to the experiment is the application of torque to the vessel. Upon pressurizing the unit and applying

torque, the following critical information may be generated:

1. Circumferential Stresses, σC

2. Longitudinal Stresses, σL

3. Principal Stresses ( σ1 , σ2 , σ3 )

4. Maximum Shear Stresses ( τ max. )


1. Two Strain Indicators (such as Micro Measurement�s P-3500) or Equivalent

2. Two Multi-port Switch and Balance Units (such as Micro Measurement�s SB-10)



Ability to Weld Aluminum



11. Exceptional Loads in Deflection

To make the Historical experiment of Deflection of Bars / Beams more interesting and challenging, the following sets of

loads are designed and recommended:

1. Sinusoidal Load 3. Uniformly Varying Load

2. Uniformly Distributed Load 4. Mixed Loads





MassCalibrationTo+/- 0.5 grams


12. Buckling of Columns

This experiment and apparatus enables the students to examine the effects of ALL parameters in the Euler�s buckling

equation [ PCR. = π 2 E I / (K L) 2 ]. Specifically, it will establish that the critical load is directly proportional to the modulus of

elasticity ( E ) of the material used and the area moment of inertia ( I ), and inversely proportional to length ( L ) and end support

condition (K � factor). The design of the apparatus also allows for simulation of intermediate supports to physically observe the

formation of other modes of buckling.


13. Impending Motion

This experiment and apparatus is designed to investigate:

1. Coefficient of Friction - µS of: Aluminum on Aluminum, Aluminum on Steel and Nylon

2. Angle of Friction 3. Impending Upward and Downward Motion 4. Multiple Sliding Surfaces

a) Upward Impending Motion b) Sliding Blocks with ability to Change Masses



14. Differential Pulleys

This experiment will generate information on:

1. Mechanical advantage of Differential Pulleys

2. Relationship between displacement and velocity of input vs. output Loads

3. Efficiency

4. Measure of Friction


15. Mechanical Advantage and Motion of Gear Trains

This experiment enables the undergraduate students to gain a comprehensive understanding of the characteristics of gear

train systems. The use of encoders and interface with LabVIEW enhances the reliability and accuracy of the collected data. The

main objectives of the experiment are to measure and obtain:

1. Mechanical advantage of simple and compound trains,

2. Relationship between displacement and velocity of input vs. output gears,

3. Efficiency 4. Velocity and acceleration of the input vs. output links

5. Effect of backlash 6. Measure of Friction

Modularity of the apparatus will allow conversion from a simple to a compound train (or vice versa) in no more than 30 seconds. This ingenious feature eliminates any unnecessary confusion in the process of conversion and saves considerable time incomparison with some commercially available units. Safety is of great concern in this design and experiment. The tooth sizes ofthe gears are selected such that even under the extreme range of loads and velocities, no damage will be done to the fingers of(curious) students - the unit will stop motion.Equipment requirements:

1. Computer 3. LabVIEW Card (National Instrument)

2. One Terminal Block 4. LabVIEW Software (National Instrument)



APPENDIX: C

A preliminary Laboratory handout for the Experiment of:

Deformation of Non-Prismatic Bars

(SPRINGS AND THEIR APPLICATIONS IN DESIGN OF EXPERIMENTS)Form groups of three (Min.) or four (Max.) for this exercise.

Using the seven available springs of equal length and diameter, the frame, the indicators and the scales on theframe, the hangers and the loads; design an experiment that may examine/address/confirm the following situations:

1. Establish the stiffness of each of the springs. Note that some of these springs show no trace of deformation up until a certain load applied. Comment and provide reasons for this condition.(i.e.: can you generate a linear/non-linear/other relationship between loads and deformations by plottingyour findings and make certain conclusions?)

2. Identify the springs with identical "K"s and examine the deformation of springs:

A- In ParallelB- In Series

(Make a DRAWING of each case.)C- Do the experimental results confirm the theoretical results?D- What is the Electrical Analog of this part of the experiment?

3. Correlate the results of step 2 with PRISMATIC BARS in uniaxial loading.[i.e.: using proper combination of springs (in series/parallel/both), show (experimentally) that

∆ = δ = F L / AE holds and discuss how the change in ∆ ( δ ) is directly proportional to

F & L and inversely proportional to A & E.] Draw the different combinations and TABULATE the results inan organized manner.

4. Using the results of the previous steps, arrange for spring combinations to show (experimentally) that ∆ = δ = Σ ( Fi Li / Ai Ei ) holds. Discuss and TABULATE the results.

5. Using a similar approach to steps 3 &4, generate (at least one more) experimental approach to show the validity of a known/unknown relationship.

6. Discuss your overall findings in this experiment and propose means to make improvements in all aspects of this exercise.

7. Prepare a professional report using the guidelines of the instructor.

design of an affordable model laboratory for mechanical ... · design of an affordable model...

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