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Reliability Engineer Certification CRE - ASQ > Reliability Designs > Flashcards

Reliability Designs Flashcards

1
Q

In a full-factorial experiment with 4 factors at 3 levels each, how many trials are required?

A

trials = levels ^ factors (VIII - 15 and 35)

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2
Q

One would say that an internal engineering comparison of actual component materials to material specifications indicates:

A

Verification (VIII - 6/7)

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3
Q

Who should be a chairperson of a design review committee?

A

The person best able to make decisions on a design (VIII - 3)

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4
Q

Having designed a test fixture to performance requirements, the design should be carefully evaluated by the reliability engineer to insure that it has included …

A

Human motor coordination factors

VIII - 61/63

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5
Q

Parts application analysis is normally performed on all parts to be used in circuits or systems.

What is most imporant when performing such analyses?

A

Proper part for the required application.

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6
Q

Derating in reliability applications is considered to be reduzing ..

A

Reducing the part stress level below rated strength levels (VIII - 77/99)

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7
Q

An engineer must design a product with a propability of success of 0.99. Assume that bouth the the strenght and stress are normally distributed and the standard deviations are the same. If the stress is known to be 3000 lbs with a standard deviation of 100 lbs, what must be the approxiamate designed strenght?

A

a) stress-strength calculation.
b) look up z value in table
c) restructure for strength

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8
Q

Which MIL symbol provides components that satisfy the requirements fo a failure rate of 50 per million hour or better?

A

R (VIII - 85)

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9
Q

A certain strut has the average strength
67000 psi and the average stress is
34000 psi.

What is the safety factor?

A

The safety factor is defined as the average strength divided by the average stress,

so 67/34 = 1.97
(VIII - 78)

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10
Q

The power of efficiency in designed experiments lies in the:

A

Hidden replication

VIII - 10/12

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11
Q

Which DOE definitions is correct? (Block)

A

A block is defined as relatively homogenous units to which different teratments can be applied (VIII - 13)

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12
Q

For a machined part, the default design tolerance should be:

A

The functional limit divided by the safety factor (VIII - 26)

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13
Q

Operations that are not critical and very repetitive sould be assigned to:

A

Machines with routine operator attention (VII - 62)

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14
Q

A 3^2 experiment means that one is considering:

A

Three levels of two factors (VIII - 35)

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15
Q

Limitations of commercial-off-shelf (COTS) software include which of the following:

A

It meets all of the required capabilities (VIII - 80/81)

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16
Q

In the design of many parts and products, it is best if the deviation from the target not exeed a certain amount. The best tolerance objective is termed:

A

Nominal-is-best (VIII - 52/53)

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17
Q

When considering whether a design should be made fault tolerant which of the following would be the last consideration

A

Which robust design approach is applicable (VIII - 74)

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18
Q

Derating parts in specific applications is performed in order to:

A

Lower the stress limits to lower failure rates (VIII - 77)

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19
Q

The rated breaking strength of a suspension bridge cable is 150’000 pounds. An example using this
cable in a derated condition is which of the following?

A

The cable in a 75’000 pound max. stress application.

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20
Q

First article testing most commonly focuses on:

A

Validation of products and processes (VIII - 6/7)

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21
Q

The strength X of a device has a normal distribution with a mean 500 and standard deviation 30. The stress Y applied to this device has a normal distribution with mean 450 and standard deviation 40.

The reliability P(X > Y) of this device for a onetime stress application.

A

a) Stress-Strength interference data calculation

[z = (mean A - mean B) / √ (standard deviation A)^2 + (standard deviation B)^2]

b) look up the propability of failure for the Z value

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22
Q

Using inferior or lower grade components may be allowed when:

A

Fault tolerant system designs are used (VIII - 74)

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23
Q

The European Union RoHS Directive for electrical and electronic equipment in effect legislates manufacturers to include in their products

A

Design for the environment (VIII - 70/71)

24
Q

The advantage of using the “modern design” method of experimentation, rather than 1 FAT is that:

A

Fewer terms and measurements are needed, for valid and useful information (VIII - 10/11)

25
Q

Commercially available generic software that has been customized for a particular application is called:

A

Modified-off-the-shelf (MOTS) software (VIII - 80/81)

26
Q

Which experimental error statement is true?

A

The error is due to an inherent variablity in the experimental technique (VIII - 15 und 18)

27
Q

There is a subtle difference between a standard parts program and a standardization program. A standardization program tends to emphasize:

A

Limited sizes (VIII - 82/83)

28
Q

The main objection to designed experimentation in an industrial environment is:

A

Getting excessive scrap as a result of choosing factor levels that are too extreme (VIII - 10/12 and 23/28)

29
Q

Derating in reliability applications is considered to be which of the following?

A

Reducing the part stress level below rated stress levels (VIII - 77/79)

30
Q

Which of the following is a correct DOE statement?

A

Varaibles are confounded when the effects of two or more factors are not seperable (VIII - 13)

31
Q

In the Taguchi loss function calculation L(y)=k(y-m)^2

What does the term m represent?

A

m = the target value (VIII - 52/53)

32
Q

Failure results when the applied loads exeeds the strength of the material in the design phase. Which factor is most important for the designer to know

A

That the load and strength figures are statistically distributed (VIII - 8/9)

33
Q

What is the best general advice to a designer to meet a high reliability requirement?

A

Use a stress-strength analysis (VIII - 8/9)

34
Q

Robust design means that the designer has attemted to:

A

Minimized random noise effects (VIII - 43/44)

35
Q

For a “smaller is better” measurement such as automobile brake pad wear, which of the following mean-squared response values has the best signal-to-noise (S/N) value?

A

smallest vallue ;) (0,03 ; VIII - 49)

36
Q

One would classify Plackett-Burrman designs as:

A

Screening Design (VIII - 41)

37
Q

Three computer drives (disks) are used in a RAID 5 configuration. The fault tolerant condition exists for:

A

Exactly one drive failure (VIII - 73)

38
Q

What is an independent element when selecting components for consideration for fault tolerance?

A

Test difficulty

Test difficulty is a disadvantage and not part of fault tolerance criteria. (VIII-73/75)

39
Q

A 2-level 5-factor experiment is being conducted to optimise the reliability of an electronic module. A half replicate of the standard full-factorial experiment is proposed. The number of treatment combinations will be:

A

16

The full-factorial experiment calls for 2 ^ 5 = 32 trials. Since the question indicates a half-factorial, then 16 trials (tests) must be conducted (VIII-15 & 32/35)

40
Q

An incomplete block design may be especially suitable when:

A

It may not be possible to apply all treatments in every block ( VIII - 29)

41
Q

The term collinear refers to:

A

Variables being a linear combination of one another.

Variables that are linear combinations of one another are colineat. This creates high correlation among the variables. (VIII-13)

42
Q

Using inferior or lower grade components may be allowed when:

A

Fault tolerant system designs are used

43
Q

First article testing most commonly focuses on:

A

Validation of products and processes

44
Q

The key to achieving design robustness is to:

A

Make the output response insensitive,

to noise variation

45
Q

Human reliability is defined as the propability that a human will:

A

Successfully accomplish a task,

within a specified time limit

46
Q

A incomplete block design may be especially suitable when:

A

It may not be possible to apply all treatments in every block.

47
Q

A designer of products whould be unlikely to undertake which reliability option?

A

Elevate the operating temperatures of components

_
Elevating the operating temperature tends to decrease reliability

48
Q

The term colinear refers to:

A

Variables being a linear combination of one another

49
Q

Three computer drives are used in a RAID 5 configuration. The fault tolerant condition exists for:

A

Exactly one drive

50
Q

Limitations of comercial-off-the-shelf (COTS software include which of the following:

A

It meets all of the required capabilities

51
Q

A process is monitored by 25 identical sensors. All sensors must function in order to provide adequate system process information.

To improve the reliability of the monitoring system ..

A

Use 23 sensors to provide the same monitoring information

_
Since each sensor has the same reliability and must function, if the system can be monitored by fewer sensors, the monitorin system reliybility would be improved. (Serial Modell)

52
Q

A company`s quality management system requires the replacement of the tool holders every 1000 hours of operation and replacement of the bearings when the machine vibration raches a certain level.

These activities are known as:

A

The tool holders replacement is preventive maintenance, the bearings are predictive maintenance.

53
Q

Failure results when the applied load exceeds the strength of the material in the design phase.

Which of the following factors is most important for the designer to know?

A

That the load and strength figures are statistically distributed.

54
Q

Information generated in a designed experiment ..

A

May be based on values which are not necessarily numerical

55
Q

A designer of products would be unlikely to untertake which reliability options?

A

Elevate the operating temperatures of components

56
Q

Which of the following product process approval activities are most likely performed by the user or customer?

A

Product validation and beta testing

Reliability Engineer Certification CRE - ASQ (10 decks)

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