AUTOMOTIVE ENGINEERING LABORATORY I LECTURER PROF.Dr. DEMIR BAYKA

INTRODUCTION APPROACH TO EXPERIMENTATION

THEORY & EXPERIMENTATION in ENGINEERING PROBLEM SOLVING APPROACHES There are 2 fundamental approaches for problem solving in engineering 1.Theoretical 2.Experimental

PROBLEM SOLVING APPROACHES 1.Theoretical:Physical / Mathematical Modeling 1.Experimental :Measurement

PROBLEM SOLVING APPROACHES Regardless of the Discipline ( ME, EE, ChE, CE,.....) or the Engineering Function ( Design, Development, Research, Manufacturing, Maintenance, etc.,..) either of these or more probably a judiciously chosen mix of these techniques is required

PROBLEM SOLVING APPROACHES Some general characteristics of these methods which will be helpful in deciding on the proper blend when choice is necessary are identified below. This also helps to organize your thinking about the whole process.

PROBLEM SOLVING APPROACHES Whenever some device or process is described with mathematical equations based on physical principles, the real world is left behind to a greater or lesser degree. i.e. all physical principles and their mathematical expression when applied to the real world situations are approximations of the real behaviour.

PROBLEM SOLVING APPROACHES These approximations may be good, fair or poor, but some disrepancy between modelled and real behaviour always exists. Although the quality of these approximations are improved as time goes by, perfection is an unreachable goal.

PROBLEM SOLVING APPROACHES We also need to remember that practical engineering, in contrast to pure science labors under constraints, sometimes overriding constraints of Time & Money

PROBLEM SOLVING APPROACHES i.e an engineer may be well aware of a nearly perfect theoretical aapproach to a problem but will conciously choose instead a simpler and less accurate method, which is judged “good enough” in terms of overall project objectives.

PROBLEM SOLVING APPROACHES Thus our first comparison of theory and experiment centers on the fact that Theories are always approximations involving simplifying assumptions where as Experiments are run on the actual system and when properly designed and executed reveal the true behaviour.

Features of alternative methods of problem solving Theoretical methods Study mathematical models of the real world which always require simplifying assumptions. Experimental methods Study the real world, no simplifying assumptions are required.

Features of alternative methods of problem solving Theoretical methods Study mathematical models of the real wold which always require simplifying assumptions. Give general results to a wide class of problems. Experimental methods Study the real world, no simplifying assumptions are required. Give results specific to the apparatus studied.

Features of alternative methods of problem solving Theoretical methods Study mathematical models of the real wold which always require simplifying assumptions. Give general results to a wide class of problems. Relaxation of assumptions leads to more complex math. model Experimental methods Study the real world, no simplifying assumptions are required. Give results specific to the apparatus studied. Higher accuracy measurements require more complex instrumentation

Features of alternative methods of problem solving Theoretical methods Study mathematical models of the real wold which always require simplifying assumptions. Give general results to a wide class of problems. Relaxation of assumptions leads to more complex math. Model. Facilities needed to commence study can be meager ( trained personnel + paper &pencil ) Experimental methods Study the real world, no simplifying assumptions are required. Give results specific to the apparatus studied. Higher accuracy measurements require more complex instrumentation. Extensive (and expensive ) laboratory facilities may be needed.

Features of alternative methods of problem solving Theoretical methods Study mathematical models of the real wold which always require simplifying assumptions. Give general results to a wide class of problems. Relaxation of assumptions leads to more complex math. Model. Facilities needed to commence studycan be meager (trained personnel + paper &pencil ) Study can commence promptly Experimental methods Study the real world, no simplifying assumptions are required. Give results specific to the apparatus studied. Higher accuracy measurements require more complex instrumentation. Extensive (and expensive ) laboratory facilities may be needed. Time delays may occur in apparatus construction and debugging

Functional types of Engineering Experiments 1.Determination of material properties and object dimensions.

Functional types of Engineering Experiments Determination of material properties and object dimensions. Determination of component parameters, variable and performance indices.

Functional types of Engineering Experiments 1.Determination of material properties and object dimensions. 2.Determination of component parameters, variable and performance indices. 3.Determination of system parameters, variables and performance indices.

Functional types of Engineering Experiments 1.Determination of material properties and object dimensions. 2.Determination of component parameters, variable and performance indices. 3.Determination of system parameters, variables and performance indices. 4.Evaluation and improvement of theoretical models.

Functional types of Engineering Experiments 1.Determination of material properties and object dimensions. 2.Determination of component parameters, variable and performance indices. 3.Determination of system parameters, variables and performance indices. 4.Evaluation and improvement of theoretical models. 5.Product / process improvement by testing.

Functional types of Engineering Experiments 1.Determination of material properties and object dimensions. 2.Determination of component parameters, variable and performance indices. 3.Determination of system parameters, variables and performance indices. 4.Evaluation and improvement of theoretical models. 5.Product / process improvement by testing. 6.Exploratory experimentation.

Functional types of Engineering Experiments 1.Determination of material properties and object dimensions. 2.Determination of component parameters, variable and performance indices. 3.Determination of system parameters, variables and performance indices. 4.Evaluation and improvement of theoretical models. 5.Product / process improvement by testing. 6.Exploratory experimentation. 7.Acceptance testing.

Functional types of Engineering Experiments 1.Determination of material properties and object dimensions. 2.Determination of component parameters, variable and performance indices. 3.Determination of system parameters, variables and performance indices. 4.Evaluation and improvement of theoretical models. 5.Product / process improvement by testing. 6.Exploratory experimentation. 7.Acceptance testing. 8.Use of physical models and analogues.

Functional types of Engineering Experiments 1.Determination of material properties and object dimensions. 2.Determination of component parameters, variable and performance indices. 3.Determination of system parameters, variables and performance indices. 4.Evaluation and improvement of theoretical models. 5.Product / process improvement by testing. 6.Exploratory experimentation. 7.Acceptance testing. 8.Use of physical models and analogues. 9.Teaching / learning through experimentation.

Functional types of Engineering Experiments 1.Determination of material properties and object dimensions. 2.Determination of component parameters, variable and performance indices. 3.Determination of system parameters, variables and performance indices. 4.Evaluation and improvement of theoretical models. 5.Product / process improvement by testing. 6.Exploratory experimentation. 7.Acceptance testing. 8.Use of physical models and analogues. 9.Teaching / learning through experimentation.

FUNDAMENTAL CONCEPTS IN MEASUREMENT & EXPERIMENTATION

WHAT IS “MEASUREMENT” ? IN GENERAL IT IS THE AQUISITION OF INFORMATION THEREFORE WITH RESPECT TO INFORMATION : 1.STRUCTURAL INFORMATION 2.METRIC INFORMATION

1.STRUCTURAL INFORMATION THIS IS THE INFORMATION ON STATE OR NATURE OF A CERTAIN CHARACTERISTIC

1.STRUCTURAL INFORMATION SO YOU ASK YOURSELF WHAT IS THE IMPORTANT CHARACTERISTIC OF THAT SOCKET ? THE ANSWER IS : VOLTAGE FOR EXAMPLE YOU WANT TO KNOW IF AN ELECTRIC SHAVER WILL WORK WHEN YOU PLUG IT IN TO THE SOCKET

AS A RESULT OF STRUCTURAL INFORMATION THE INDEPENDANT VARIABLES THAT SHOULD BE OBSERVED ARE DETERMINED 1.STRUCTURAL INFORMATION THE AQUISITION OF STRUCTURAL INFORMATION IS CALLED QUALITATIVE MEASUREMENT

2.METRIC INFORMATION THIS IS THE INFORMATION ABOUT THE QUANTITY OF AN INDEPENDANT VARIABLE. IT IS OBTAINED AS A RESULT OF QUANTITATIVE MEASUREMENT

IN THE FIELDS OF SCIENCE AND ENGINEERING BOTH STRUCTURAL AND METRIC INFORMATION IS NECESSARY. BEFORE METRIC INFORMATION IS AQUIRED STRUCTURAL INFORMATION IS NEEDED

QUANTITATIVE MEASUREMENTS ARE ABOUT : MATERIAL PROPERTIES DENSITY THERMAL CONDUCTIVITY HEATING VALUE VISCOSITY MELTING POINT LATENT HEAT OF EVAPORATION ELASTIC MODULUS SPECIFIC HEAT ETC…...

QUANTITATIVE MEASUREMENTS ARE ABOUT : COMPONENT PARAMETERS DIAMETER MASS SPRING CONSTANT ELECTRICAL INDUCTANCE FLUID CAPACITANCE THERMAL RESISTANCE ETC…...

QUANTITATIVE MEASUREMENTS ARE ABOUT : VARIABLES OF STATE POSITION FORCE VOLTAGE PRESSURE TEMPERATURE DIFFUSION RATE ETC…...

SOME ASPECTS OF A MEASUREMENT DESCRIPTIVE SELECTIVE OBJECTIVE

REASONS FOR PERFORMING MEASUREMENTS 1.TO PROVIDE AN IMMEDIATE QUANTITATIVE ANSWER TO A SPECIFIC PROBLEM properties of a specific material parameters of a specific object or a component the state or performance of a specific system including system identification

REASONS FOR PERFORMING MEASUREMENTS 1.TO PROVIDE AN IMMEDIATE QUANTITATIVE ANSWER TO A SPECIFIC PROBLEM systematic experimental tests to design and to develop new products

REASONS FOR PERFORMING MEASUREMENTS 1.TO PROVIDE AN IMMEDIATE QUANTITATIVE ANSWER TO A SPECIFIC PROBLEM monitor and control engineering systems for their proper operation and maintenance

REASONS FOR PERFORMING MEASUREMENTS 1.TO PROVIDE AN IMMEDIATE QUANTITATIVE ANSWER TO A SPECIFIC PROBLEM To perform acceptance testing of components or systems by authorized agencies to demonstrate their conformity with preset standards before their use

REASONS FOR PERFORMING MEASUREMENTS 2.TO COLLECT EMPIRICAL DATA WITH THE HOPE OF OBTAINING AN INSIGHT INTO A PHENOMENON AND LATER GO ON TO USE THE DATA TO FORM A THEORETICAL EXPLANATION OF IT.

REASONS FOR PERFORMING MEASUREMENTS 3.TO VERIFY THE EXISTING THEORY To collect data for complementing, verifying, and improving these theoretical or empirical models, hypotheses, theorems, and laws by conducting “controlled experiments”.

DISCOVERY OF NEPTUNE AT 1820 FRENCH ASTRONOMER ALEXIS BOUVARD OBSERVED A DESCREPENCY IN URANUS ’S PATH AS PREDICTED BY NEWTON’S LAW

THE DEVIATION WAS SMALL BUT IT WAS MORE THAN THE UNCERTAINTY OF THE MEASUREMENT

NEWTON’S LAW OF GRAVITY WAS FORMULATED AS A HYPOTHESIS FOR EXPLAINING THE OBSERVATIONS OF TYCO BRAHE KEPLER AND GALILEO

UNTIL THEN THOUSANDS OF PREDICTIONS HAD BEEN MADE AND THE PREDICTIONS HAD BEEN OBSERVED NOW THERE WAS A NEW OBSERVATION WHICH DID NOT AGREE

WHAT SHOULD BE DONE ? 1. FORMULATE A NEW HYPOTHESIS WHICH WILL ALSO EXPLAIN THE NEW OBSERVATION 2. MODIFY THE BASIS OF THE EXISTING THEORY (ASSUMPTION OF THE FIXED NUMBER OF PLANETS)

A HYPOTHETICAL NEW PLANET WAS CALCULATED AND LATER OBSERVED THUS NEPTUNE WAS DISCOVERED LATER PLUTO WAS DISCOVERED IN THE SAME MANNER

FOR TYPES 1 & 2 THE FOLLOWING APPROACH CAN BE USED

STEP A.1 QUESTION WHAT IS THE OBJECTIVE OF THE EXPERIMENT ?

STEPPOSSIBLE ACTION A.1 a)THE PROBLEM MAY HAVE BEEN CLEARLY DEFINED FOR YOU b)YOUR EXPERIENCE MAY HELP YOU TO DEFINE AN OBJECT c)IN AN UNFAMILIAR SITUATION TRY A FEW TENTATIVE TESTS FROM WHICH AN OBJECTIVE MAY SUGGEST ITSELF

STEPCONCLUSION A.1 OBJECTIVE IS DEFINED AND NOTED

STEPQUESTION B.1 WHAT ARE THE IMPORTANT VARIABLES AND ARE THEY DEFINED ?

STEPPOSSIBLE ACTION B.1 a)THE ANSWER MAY BE SELF EVIDENT b)STEP A.1 MAY GIVE YOU A LEAD (BEWARE OF INCLUDING DEPENDENT VARIABLES)

STEPCONCLUSION B.1 THE VARIABLES ARE SELECTED AND PERHAPS A HYPOTHESIS IS MADE

STEPQUESTION B.2 WILL GROUPING OF VARIABLES REDUCE THE AMOUNT OF TESTING ?

STEPPOSSIBLE ACTION B.2 a)GROUPING CAN BE BASED ON PHYSICAL ARGUMENTS b)PERFORM A DIMENSIONAL ANALYSIS

STEPCONCLUSION B.2 ANY GROUPINGS ARE DECIDED UPON

STEPQUESTION C.1 WHAT APPARATUS IS REQUIRED ?

STEPPOSSIBLE ACTION C.1 a)YOU WILL HAVE TO WORK WITHIN THE LIMITS OF THE APPARATUS AVAILABLE ( DO YOU NOW HAVE TO REVISE THE CONCLUSION OF B.1) ? CONCLUSION OF B.1 THE VARIABLES ARE SELECTED AND PERHAPS A HYPOTHESIS IS MADE b)REQUEST ADDITIONAL FACILITIES

STEPCONCLUSION C.1 NECESSARY EQUIPMENT IS NOW AVAILABLE

STEPQUESTION C.2 HOW WILL THE TESTS BE ORGANIZED ?

STEPPOSSIBLE ACTION C.2 a)DECIDE WHICH QUANTITIES YOU WILL VARY AND IN WHAT ORDER b)DECIDE WHO IS GOING TO DO WHAT

STEPCONCLUSION C.2 TEST PLAN IS DRAWN UP AND JOBS ARE ALLOCATED

STEPQUESTION C.3 HOW WILL THE DATA APPEAR ON YOUR NOTES ?

STEPPOSSIBLE ACTION C.3 a)DECIDE ON THE RANGE OVER WHICH EACH VARIABLE MAY CHANGE C.1 a) MAY IMPOSE A LIMITATION C.1a)YOU WILL HAVE TO WORK WITHIN THE LIMITS OF THE APPARATUS AVAILABLE

STEPPOSSIBLE ACTION C.3 a)DECIDE ON THE RANGE OVER WHICH EACH VARIABLE MAY CHANGE C.1 a) MAY IMPOSE A LIMITATION b)PREPARE A TABLE INTO WHICH DATA CAN BE ENTERED. IS A REFERENCE TEST NUMBER NEEDED ? c)DECIDE WHETHER ACCURACY OF THE MEASUREMENTS WILL ENSURE A MEANINGFUL RESULT d)PREPARE AXIS ON WHICH CONTROL CURVES CAN BE PLOTTED

STEPCONCLUSION C.3 a)NOTEBOOKS ARE PREPARED b)TEST IS PERFORMED c)DATA IS RECORDED d)CONTROL CURVES ARE DRAWN

STEPQUESTION D.1 WHAT DO THE CONTROL CURVES SHOW ?

STEPPOSSIBLE ACTION D.1 a)TAKE ADDITIONAL READINGS WHERE BAD POINTS OCCUR b)TAKE ADDITIONAL READINGS IN BADLY DEFINED AREAS

STEPCONCLUSION D.1 DATA IS NOW COMPLETE

STEPQUESTION E.1 HOW WILL THE RESULTS BE PRESENTED ?

STEPPOSSIBLE ACTION E.1 a)DECIDE BETWEEN GRAPHICAL, TABULAR OR FORMULA PRESENTATION b)IF (a) DEMANDS IT PERFORM A CURVE FITTING EXERCISE

STEPCONCLUSION E.1 RESULTS ARE ANALYSED

STEPQUESTION E.2 WHAT DO THE RESULTS MEAN ?

STEPPOSSIBLE ACTION E.2 a)ESTABLISH THE VALIDITY OR OTHERWISE OF THE HYPOTHESIS MADE IN B.1 b)ESTABLISH THE CONFIDENCE WHICH CAN BE PLACED IN THE NUMERICAL RESULTS c)EXPLAIN THE NATURE OF ANY TRENDS d)EXPLAIN DEVIATIONS FROM ANY THEORETICAL EXPECTATIONS

STEPCONCLUSION E.2 a)RESULTS ARE ANALYSED b)EXPERIMENTAL ERRORS ARE INVESTIGATED c)DISCUSSION SECTION IS WRITTEN

STEPQUESTION F.1 IS THE TEST FINISHED ?

STEPPOSSIBLE ACTION F.1 a)STATE THE LAWS YOU HAVE DISCOVERED b)STATE ANY FURTHER INVESTIGATION YOU CONSIDER NECESSARY

STEPCONCLUSION F.1 CONCLUSIONS ARE DRAWN AND RECOMMENDATIONS MADE

STEPQUESTION F.2 HAVE YOU FINISHED ?

STEPPOSSIBLE ACTION F.2 a)PROCEED AS DICTATED BY F.1(b) b)STATE ANY FURTHER INVESTIGATION YOU CONSIDER NECESSARY F.1

STEPCONCLUSION F.2 TEST CONTINUES OR REPORT IS PREPARED