AME300_HW1

CHAPTER 1 PROBLEMS 1.14 115 1.16 117 A bulb thermometer hangs outside a house window. Comment on extraneous variables that might affect the difference between the actual outside temperature and the indicated temperature on the thermometer. A synchronous electric motor test stand permits either the variation of input voltage or the output shaft load with the subsequent measurement of motor efficiency, winding tem- perature, and input current. Comment on the independent, dependent, and extraneous variables for a motor test. The transducer specified in Table 1.1 is chosen to measure a nominal pressure of 500 cm H,O. The ambient temper- ature is expected to vary between 18 °C and 25 °C during tests. Estimate the possible range (magnitude) of each listed elemental error affecting the measured pressure. A force measurement system (weight scale) has the follow- ing specifications: Range Linearity error Hysteresis error Sensitivity error Zero drift 0to 1000 N 0.10% FSO 0.10% FSO 0.15% FSO 0.20% FSO 118 L19 1.20 121 1.22 L23 1.24 Estimate the overall instrument uncertainty for this system based on available information. Use the maximum possible output value over the FSO in your computations. State the purpose of using randomization methods during a test. Develop an example to illustrate your point. Provide an example of repetition and replication in a test plan from your own experience. Develop a test plan that might be used to estimate the aver- age temperature that could be maintained in a heated room as a function of the heater thermostat setting. Develop a test plan that might be used to evaluate the fuel efficiency of a production model automobile. Explain your reasoning. A race engine shop has just completed two engines of the same design. How might you, the team engineer, determine which engine would perform better for an upcoming race (a) based on a test stand data (engine dynamometer) and (b) based on race track data? Describe some measurements that you feel might be useful, and explain how you might use that information. Discuss possible differences between the two tests and how these might influence the interpretation of the results. Develop a test plan to compare tool life for three different types of drill bits for a drilling process in stainless steel. How would cost enter this test plan? Develop a test plan to determine the optimum driver loft for an individual golfer. How would the test plan differ if 1.25 1.26 1.27 1.28 1.29 1.30 131 1.32 1.33 the player wished to optimize carry or total distance? Note: A little research or a conversation with a golfer might help, A thermodynamics model assumes that a particular gag behaves as an ideal gas: Pressure is directly related to temperature and density. How might you determine that the assumed model is correct (validation)? Regarding the Mars Climate Orbiter spacecraft example presented, discuss how verification tests before launch could have identified the software units problem that led to the catastrophic spacecraft failure. Explain the purpose of verification testing? A large batch of carefully made machine shafts can be man- ufactured on 1 of 4 lathes by 1 of 12 quality machinists. Set up a test matrix to estimate the tolerances that can be held within a production batch. Explain your reasoning. Suggest an approach or approaches to estimate the linearity error and the hysteresis error of a measurement system. Suggest a test matrix to evaluate the wear performance of four different brands of aftermarket passenger car tires of the same size, load, and speed ratings on a fleet of eight cars of the same make. If the cars were not of the same make, what would change? The relation between the flow rate, Q, through a pipeline of area A and the pressure drop Ap across an orifice-type flow meter inserted in that line (Figure 1.15) is given by Q= CA4/2Ap/p where p is density and C is a coefficient. For a pipe diameter of 1 m and a flow range of 20 °C water between 2 and 10 m*/min and C = 0.75, plot the expected form of the calibration curve for flow rate versus pressure drop over the flow range. Is the static sensitivity a constant? Incidentally, the device and test method is described by both ANSI/ASME Test Standard PTC 19.5 and ISO 5167. The sale of motor fuel is an essential business in the global economy. Federal (U.S.) law requires the quantity of fuel delivered at a retail establishment to be accurate to within 0.5%. (a) Determine the maximum allowable error in the delivery of 25 gallons (or use 95 L). (b) Provide an esti- mate of the potential costs to a consumer at the maximum allowable error over 150,000 miles (240,000 km) based on - an average fuel mileage of 30.2 mpg (7.8 L/100 km). (c) As aknowledgeable consumer, cite one or two ways for you to identify an inaccurate pump. Using either the ASME 19.5 or ISO 5167 test standard, explain how to use a venturi flowmeter. What are the inde- pendent variable(s) and dependent variable(s) in engineer- ing practice? Explain. A piston engine manufacturer uses four different subcon- tractors to plate the pistons for a make of engine. Plating thickness is important in quality control (performance and part life). Devise a test matrix to assess how well the man- ufacturer can control plating under its current system. Scanned with CamScanner

" Chapter 1 Problems 146 The acceleration of a cart down a plane inclined at an angle ato horizontal can be determined by measuring the change in speed of the cart at two points, separated by a distance s, along the inclined plane. Suppose two photocells are fixed at the two points along the plane. Each photocell measures the time for the cart, which has a length L, to pass it. Iden- tify the important variables in this test. List any assumptions that you feel are intrinsic to such a test. Suggest a concomi- tant approach. How would you interpret the data to answer the question? 1.47 In general, what is meant by the term “standard”? Discuss your understanding of the hierarchy of standards used in calibration beginning with the primary standard. How do these differ from test standards and codes? 1.48 Acommon scenario: An engineer has two pencil-style pres- sure gauges in her garage for setting tire pressures. She notices that the two gauges disagree by about 14 kPa (2 psi) on the same tire. How does she choose the most accurate gauge to set car tire pressures? Discuss possible strategies she might use to arrive at her best option. 1.49 Explain the potential differences in the following evalua- tions of an instrument’s accuracy. Figure 1.11 will be use- ful, and you may refer to ASTM E177 if needed. a. The closeness of agreement between the true value and the average of a large set of measurements. b. The closeness of agreement between the true value and an individual measurement. 1.50 Research ASTM F 558: Air Performance of Vacuum Cleaners. Write a short summary to describe the intent, and give an overview of this test standard. 1.51 Research the following test standards and codes. Write a short summary to describe the intent, and give an overview of each code: a. ANSI Z21.86 (Gas Fired Space Heating Appliances) b. ISO 10770-1 (Test Methods for Hydraulic Control Valves) ¢. ANSI/ASME PTC19.1 (Test Uncertainty) d. ISO 7401 (Road Vehicles: Lateral Response Test Methods) e. I1SO 5167 Parts 1-4 1.52 A hotel chain based in the United States contracts with a European vacuum cleaner manufacturer to supply a large number of upright cleaner units. After delivery, the hotel raises questions about manufacturer vacuum cleaner per- formance claims pointing out that the units should have been tested to meet ASTM 558, an American standard. The manufacturer notes the advertised performance is based on IEC 60312, a European standard, and the two test codes will yield similar, if not exact, results. Investigate both test codes and address similarities and differences. Is there is a legitimate claim here? 1.53 1.54 1.55 156 157 Test code ASTM 558-13 allows for the comparison of the maximum potential air power available between vacuum cleaners when tested under the prescribed conditions. The test requires using at lcast three units for each make/model tested with the units obtained at random. Explain what might be a reasonable way to meet this requirement. Explain a possible reason for this requirement. Suggest a reasonable number of significant digits for report- ing the following common values, and give some indication of your reasoning: a. Your body weight for a passport b. A car's fuel usage (use liters per 100 km) c. The weight of a standard (“Good Delivery") bar of pure (at least 99.99%) gold Using spreadsheet software (such as Microsoft Excel), create a list of 1,000 numbers each randomly selected between 100 and 999. Divide each number by 10 to obtain a trailing digit; this will be Column 1. Each number in Column 1 will have three significant digits. In Column 2, have the spreadsheet round each number using the default ROUND function to two significant digits. In Column 3, have the spreadsheet round each number in Column 1 per ASTM E29 (e.g., (=IF(MOD(ALI)= 0.5MROUND(A1,2),ROUND(A1,0)). Compute the sum of each column and compare. Discuss the meaning of the operations and the results, and explain any differences due to rounding errors. How many significant digits are present in the following numbers? Convert each to scientific notation. L 1002 5. 0.1x103 2. 0.00034 6. 999 kg/m’ 3. 2500 7. Population 152,000 4. 04202 8. 0.000001 grams Round the following numbers to 3 significant digits. (i) 15.963 (v) 21.650 (i) 1232 kPa (vi) 0.03451 (iii) 0.00315 (vii) 1.82512314 (iv) 21.750 (vii) 1.2350x 10~* 1.58 Express the result by rounding to an appropriate number of significant digits. @ sin()=;n=0010m™,Xx=573m (i) & = (i) In(0.31)= (iv) xylz=3;x=423.0,y=3342),2=11.32 v) (0212 +03212 +0.1212)/3 = (vi) 1072 +6542= (vii) 2212 = (viii) (223 +16.634)x 59 = Scanned with CamScanner