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19 Cards in this Set

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breifly describe the design of the o-rings, and why they failed

sections instead a single part




tang and clevis




compress and expand




due to may factors including communication and managment




launched on a cold day




pressure cause oring to compress, did not expand in time




deflagration






The solid rocket booster was designed in sectionsinstead of a single parts because Norton thycol was located in Arizona, and theonly way they could ship the parts were in sections by train. These sectionswere placed together in a tang andclevis with two orings, one acting as the primary seal and the other as abackup seal. The rubber orings were mean to compress and decompress with thepressures caused by the hot gasses in the SRB. Unfourtunately, due to manyfactors including communication and management, Nasa decided to launch on avery cold day and the orings could not functioun properly under lowtemperatures. Pressure forced the orings to compress, but they could not retractin time which allowed hot gasses to escape through the joint and pierce intothe fuel tank leading to deflagration.

What was the political and social context of the decision to proceed with the space shuttle project? describe the effect these factors had on the difficulty of the project

ppl not interested in space



war = low budget



promised cost efficitent, reusable, send regular people



Increased scope, 45% cargo



space truck easy



pressured on time



NASAwas building the space shuttle at a time when people were not as interested inspace anymore. Furthermore, war was led to a reduced space budget. This madethe project much more difficult. Nasa was also increasing the scope of theproject to carry more weight into space and made the cargo bay 45% bigger. The shuttleprogram promised hope to the people to be cost efficient, reusable, and theidea of sending regular people to space like a teacher. They advertised it as aspace truck and tried to come across on how easy it was to operate. Otherfactors were decreased time to buld, increased pressure and less money to workwith.

what is all up testing? what are the trade offs that would need to be considered in making a decision to adopt such a testing methodology?

all up- build the bitch then test




bottom up- test everything along the way




7million parts, impossible to do bottoms up.




ideal to come up w/ a combination of the two aproaches




the higher the higher the complexity but the higher the reward




All up testing is when the product is completelydesigned and built, then finally tested. Bottom up testing is when every partof the component is tested before the product can be put together and testedone last time. Although Bottom up testing is safer, it is not as practical asall up testing. Bottom up testing is very expensive and time consuming. Whendealing with a project such as the space shuttle, there is over 7 million partsthat consist of the shuttle. There is no way to individually test every part,that is why an all up approach was taken. It is ideal to come up with acombination of the two approaches to receive the maximum amount of testingwhile still being cost effective and meet deadlines.

discuss the adequacy of the data the engineers presented to their management when they reccommeded against the launch. discuss both the format and the context of the data

Roger Boisjoly




messy, hand written




uneccesary information




hard to understand




incoclusive




insufficient data to draw a conclusion




should have made it more quantitative




charts, graphs and regression lines




once you lose your audience you lose your credibility






The presentation given by Roger boisjoly was notgood enough. From what we saw in class the data presented was messy handwritten, filled with unessary information making it had to understand. The datawas inconclusive. There were only 2 data points on the slides, 22 othermissing. There was insufficient data to draw a conclusion. The information wasnot adequate. They needed to make it more quantitative with only necessaryinformation and a chart shown with a regression line so that it can be easilyunderstood by the audience. Once you loose your audience you loose yourcredibility.unX;)

what is the ethical lesson of the challenger?

even when there is pressure, speak up



have right data to support theory



communication



Management has deadlines





The ethical lesson that was learned was thatthere is pressure from management, and other sources, but you need to speak upwhen there is a major problem. There is also a need to have the right data tosupport your theory. Also, communication of the problem with the right peopleis important. When lives are involved it is important to stick to your ethics,even f it means going against management a risking your career.

what are value based decision? what are factors that need to be considered in making such a decision?

knowledge




data




information




experience




make a vbd by understanding level of uncertanty




make a decision where you can live with the consequences




having to choose a material for a part




what to do with inconclusive data



A value based decisionis a decision that you make based on knowledge, data, information andexperience. Data may conflict with your decision, but an engineer must make avbd by understanding the level of uncertenty. It is to make a decision whereyou can live with the conswquences. And example of making a vbd is when havingto choose a material for a part or choosing what to do with inconclusive data.ۃXt[

why is murphys law inevitable consequence of modern engineering design?

project are always really complex



failure of one part can lead to failure of mult. systems



Can't test errything



more complexity = more uncertanty



Murphys law states what can go wrong will go wrong. Murphys lawhappens in modern engineering because products are becoming more complex andfailure of a single part can cause the whole system to fail. With morecomplexity comes more uncertainty YXٜ

why can engineering data be uncertain? how do engineers deal with uncertain data?

1) tested like gravity


2) empiriacly tested like strss vs strain


3)known missing knowledge like climate4)unkown missing knowledge- don’t know whatyou don’t know


No datum stands alone, ask yourself is thedatat reliable.

discuss the uncertainties associated with testing. how does the engineer resolve these difficulties?

Harder to prove something is reliable



40-90% happens due to fatigue



light bulb in on for an hour



deals with this by making value based decisions



It easy to prove its unreliable, but who knows howlong it will be reliable. Therefore it is harder to prove something isreliable. For example you can turn on a light bulb for an hour and you cannotsay it will not burn out, but you can say it did not burn out for an hour. An engineerdeals with these problems by making a value based decision.one, X!

discuss the difficulties of complexity in design

increasing complexity = increase uncertenty



always better to keep it simple



Silent killer of engineering





Complexity is an increasing problem with design, byincreasing the complexity you increase the uncertainty. An example is the f35. Becausethe plane is designed to cater to multiple branches of the military thecomplexity of the aircraft is very high, therefore the uncertainty isincreased. There is also limited time, budget, and managemet pressure which iswhy it is a engineering failure. It is always best to keep it simple. X

Describe project issues

STAR(scope, budget, safety, deadline, quality)




Your project is likely very behind from the beginning




All of these project determinants are interdependent




When you have to make trade offs, the decisions do not havepredictable consequences.




Mythical man month

what is material selection and use?

Inclomplete knowledge of behavior of materials in the faceof extreme conditions such as temp or magnetic fields, friction or corrosion)




We have to make decisions on what materials to choose




No material is ideal, particularly when viewed across the fullproduct cycle.




An example was the choice of the rubber they used for theo-rings and how they acted at extremely low temperatures they did not plan on operationin.

what is software problems?

Potentially unreliable software




May be to complexProgramed by humans, eith limited time and money to completeproject




Data supplied to model could be unreliable




Example is the complex coding found in the millions of linesof code for the f35 continues to be delayed.

what are human factors?

Problems contributed by the user (when your custome doesstuipid stuff with your product)




Problem caused by engineer such as the engineer thinking thecustomer can figure it out.

how can there be organizational and communication errors?

Within the organization (nasa)



Within the system theselves- the system can be unorganized c



-in organizations


-within systems themselves


-see challenger disaster for example


What are the types of uncertain data?

Tested



TestedEmpirically


Empirically tested



Known missing



Unknown missing

What are the project issues?

Scope



Budget



Reliability



Safety



Deadline

What is Newton Airport identifier

KEWK

What is the elevation at KEWK?

1530 ft