73 terms

Introduction to Mechanical Engineering Final


Terms in this set (...)

Vat photopolymerization
Builds parts by using light to selectively cure a vat of photopolymer
Material jetting
Builds parts by depositing small droplets of photopolymer (similar to inkjet) which are then cured by exposure to light
Binder jetting
Creates objects by squirting a binding agent into a powderized material
Material extrusion
Creates objects by extruding a thin strand of thermoplastic to build layers. Linked to a tube of toothpaste or syringe
Powder bed fusion
Melts fine layers of powderized plastic or metal into solid objects using a laser
Sheet lamination
Builds parts by trimming sheet of material and binding them together in layers
Directed energy deposition
Parts are built or repaired by using focused thermal energy to fuse materials as they are deposited
Fused Deposition modeling AKA FFF-fused filament fabrication
Who is FDM trademarked by
Material extrusion and thermoplastic
Selective Laser Sintering-powder bed fusion
Direct metal laser sintering-powder bed fusion
Short for stereolithography apparatus -vat polymerization
High speed sintering of heat-sensitive carbon black ink -powder bed fusion
Selective laser melting - powder bed fusion
Big area additive manufacturing, refers to large scale machines used in construction or manufacturing to produce large prints
Electron beam melting- powder bed fusion
AM Process steps
-Computer Aided Design
-STL convert
-File transfer to AM system
-Machine Setup
-Post process
Part sizes for Vat photopolymerization
12in^3 to 75,000 in^3
Part sizes for Material jetting
Less than 25,000 in^3
Part sizes for Material extrusion
Less than 32,000 in^3
FFF/FDM Machine settings
-Layer height-intended height of each layer of melted filament in a model
-retraction-filament from a part
-print temperature -material dependent
-bed temperature
-supports (full partial & raft)
-filament diameter - 2 standards in FDM/FFF
-print speed/extruded speed
-fill density
-layer times
-cooling fam off/on
-shell thickness remember, not solid
-bottom/top thickness
-flow percentage
-travel speed
-infill speed
AM software polymers
What is a team
A group with complementary skills, committed to a common purpose, have common goals, share a common working approach, held accountable for the work product
Purpose of a team
Comped tasks, creativity, efficient use of resources, getting the job done quickly
What do high performance teams have?
Clear goals, work plan, clearly defined team roles, clear communication in the team, beneficial behaviors, defined decision procedures, balanced team member participation, established ground rules, awareness of group interactions, use of scientific approach
Leadership principles
Know yourself and seek self improvement, be technically and tactically proficient, seek and take responsibility, make sound and timely decisions, set the example, know your team members and look out for their welfare, keep your team members informed, develop a sense of responsibility in your team members, ensure that tasks are understood, supervised, and accomplished, train your team members as a team, employ your team in accordance with its capabilities
Group life cycle
Infancy- getting started, who's who, purpose
Adolescence- how should we organize? Who leads? Process to reach goals?
Adulthood- work together and compliment each other's abilities, get job well sone
Stake holder
Anyone who has interest in an organization
Core collaboration
Smaller team, key individuals needed to make decisions
They meet more frequently for shorter periods typically to make decisions or resolve issues
Extended team
Comprised of people called in when specialized resources, information, or ideas are needed
They are invited to attend portions of the Core Team meeting when necessary
Meetings less frequently as a way to communicate and share ideas - not a forum to make decisions
Communication conflict resolution
Common purpose and goals, accountable for work product, clearly defined roles, defined decision procedures, balanced participation
Mission statement
Defines goals, ethics, culture, and norms for decision making
What the company (team) does for customers, employees, owners, community, world
-Avoid vagueness, 1-2 paragraphs, readable in 30 sec
-Answers: who is company, what do you do/stand for/ why, do you make a profit, what markets are you serving, benefits, do you solve a problem for customers, what kind of internal work environment
Design process
1 Define the problem -identify criteria and constraints
-ask questions
2 Research
-similar problems and analogs
3 Brainstorm solution
4 Choose a solution
5 development
-proof of concept
6 build a prototype
-physical and virtual
7 test
design process reworked
Problem definition
-what are you really trying to do
Concept formation
-offer solutions
-everything on the table
Concept evaluation
-does it meet requirements
-strength weakness
-resources available
-solve the problem
Concept selection
-which best meets requirement
-can it be done
-mix and match
Detailed design
-application of engineering tools
-physical dimensions and fit
-material selection
-manufacturing process
-order of accessibility
-simulation (motion /stress)
-physical prototype (does it actually work, success?, refinements/redesign)
-real world use conditions
-how can you recreate conditions
-testing of sub-assemblies
-failure now what?
Send to production
Approved or rejected
(And DOCUMENTATION the entire time)
Steps of a problem solving cycle
1 understand the problem through collecting data
-state the problem, look at the problem carefully
-redefine the problem redefine it to eliminate bias
-identify constraints
2 choosing strategy
-identify alternative solutions
-analyze the alternatives
-select the most viable
3 solve the problem and analyze the results to see if they meet the specifications
4 iterate the cycle until you find a solution
Factorial experiment
Experiment consisting of 2+ changing factors,
They take on all possible combinations
How many experiments can 2 factors have?
Steps of factorial
1 Choose n variables that affect the response
2 vary them +5% and -5%
3 run experiments for all combinations 2^n
4 from the results find effect of each factor in response
5 also find the interaction between the factors
6 use charts to display
7 write an equation for the response with the variations
What are some professional societies
What is ASME
The society for ME's, networking, professional development, benefits, technological advancement, eduaction
ASME at Auburn
Networking, job opportunities, competitions,
Networking, student enrichment, learn about profession, scholarships
Optimization definition
An act, process, or methodology of making something (as a design, system, or decision) as fully perfect, functional, air effective as possible
Mathematical procedures (as finding the maximum of a function) invilved
Problem statement has
Design variables, objective function, constraints, and parameter
Optimization steps**
1. Establish purpose or objective
2. Establish design space -physical constraints
3. Establish variables and parameters
4. Optimize topology (FEA & other tools)
5. Refine and smooth design
6. Validate design though design tools
7. Test
Types of FMEA
Design- analyze product design preproduction, focus on product functions D analyze systems ASM subsystems in early concept and design stages
Process- used to analyze manufacturing and assembly processes after they are implemented
Failure Modes & Effects Analysis
FMEA Procedure
1. For each process input (start with high value inputs) determine the ways in which the input can go wrong (failure mode)
2. for reach failure mode, determine effects -select a severity level for each
3. Identify potential causes of each failure mode -select an occurrence level for each cause
4. List current controls for each cause -select detection level for each cause
5. Calculate RPN risk priority number
6. Develop recommended actions, assign responsible persons, take actions - give priority to high RPN Must look at severities rated 10
7. Assign predicted severity, occurrence, and detection levels and compare RPNs
Assessment of the seriousness of the effect of the potential failure mode on the next component, subsystem, or customer if it occurs
It applies to effects
For failure modes with multiple effects, rate each effect and select the highest rating as severity for failure mode
Likelihood that a specific cause or mechanism will occur
Be consistent with assigning occurrence
Removing or controlling the cause/mechanism through a design change is only way to reduce the occurrence rating
Detection values should correspond with AIAG SAE
If detection values are based upon internally defined criteria, a reference must be included in FMEA to rating table with explanation for use
Detection is the value assigned to each detective controls
Detection values of 1 must eliminate the potential for failure as due to design deficiency
multiplication of the severity, occurrence and detection ratings
Lowest detection rating is used to determine RPN
RPN threshold should not be used as the primary trigger for definition of recommended actions
Severity x occurrence x detection RPN prioritizes concern. The higher the value the more urgent. 1-1000
RPN scaling: severity 1-10
Occurrence 1-10
Detection 1-10

RPN are comparable within the analysis. A RPN from one can't compare to that of another
Input and output fmea
Input: process map, process history, procedures, knowledge, experience.
Outputs: list of actions to prevent causes or detect failure modes, history of actions taken
Assumptions of DFMEA
All systems/components manufactured or assembled as specified by design
Failure could but will not necessarily occur
Potential failure mode
The manner in which a system, subsystem, or component could potentially fail to meet design intent
Things to consider upon failure
Absolute partial intermittent failure over function degraded function unintended function
Operating conditions
Hot and cold or wet and dry or dusty and dirtu
Above average life cycle harsh encironment
10 steps to FMEA
1. Review the design process
2. Brainstorm potential failure modes
3. List potential failure effects
4. Assign severity ratings
5. Assign occurrence ratings
6. Assign detection ratings
7. Calculate RPN
8. Develop an action plan to address high RPN
9. Take action
10. Reevaluate the RPN after the actions are completed
Reasons FMEA fail
1. One person is assigned to complete the FMEA
2. Not customizing the rating scales with company specific data so they are meaningful for your company
3 the design or process expert is not included in the FMEA or is allowed to dominate the FMEA team
4. Members of the FMEA team are not trained in the use of FMEA and become frustrated with the process
5. FMEA team becomes bogged down with minute details of design or process, losing sight of the overall objective
6. Rushing though identifying the failure modes to move onto the next step of the FMEA
7. Listing the same potential effect for every failure
8. Stopping the FMEA process when the RPNs are calculated and not continuing with the recommended actions
9. Not reevaluating the high RPNs after the corrective actions have been completed
Engineering ethics
1. Te activity of solving moral problems by understanding developing justifying moral judgements related to engineering issues
2. The development of rand compliance to currently accepted ethical slides of conduct
Implications rather than scientific fact or discovery
National society of professional engineers
American society of Mechanical engineeris
NSPE Fundamental canons
1. Hold paramount the safety health and welfare of the public
2. Perform services only in the area of their competence
3. Issue public statements only in an objective and truthful manners
4. Act for each employer or client as faithful agents or trustees
5. Build their professional reputation on the merit of their services and shall not compete unfairly with others
6. Conduct them salve honorably responsibly ethically and lawfully so as to enhance the honor reputation and usefulness of the profession and associate only with reputable persons and organizations
ASME canons
1. Engineers shall hold paramount the safety health and welfare of the public in the performance of the professional duties
2 engineers shall perform services only in the areas of their competence
3. Engineers shall continue their professional development throughout their careers and shall provide opportunities for the procreation am and ethical development of those engineers under their supervision
4. Engineers shall act in professional matter for each employer as faithful agents or trustees and shall avoid conflicts of interest or the spear acne of conflicts of interest
5. Engineers shall build their professional reputation on the merit of their services and shall not complete unfairly with others
6. Engineers shall associate only with reputable persons or organizations
7. Engineers shall issue public statements only in an objective and truthful manner
8. Engineers shall consider environmental impact in the performance of their professional duties
9. Engineers shall not seek ethical sanction against another engineer unless there is a good reason to do so under the relevant codes, policies, and procedures governing that engineers ethics conduct
10. Engineers who are members of the society shall endeavor to abide by the constitution, by laws and policies of the society and they shall disclose knowledge of any matter involving another members alleged violation of this code of ethics of the society's conflicts of interest policy in prompt complete and truthful manner to the chair of the ethics committee
ASME principles
1 Use their knowledge and skill for the enhancement of human welfare
2 being honest and impartial and serving with fidelity the public, their employers and clients and
3 striving to increase the competence and prestige of the engineering profession
Hazard recognition
Kinematic hazards, energy hazards, electrical/chemical/nuclear hazards, biological hazards, human factor hazards, misuse and abuse hazards, environmental hazards, danger severity, length of exposure, short and long term affects, frequency of occurrence, environmental impact
Hazard avoidance
Modify, guard, warn, train
Personal safety
Shut off switches, first aid kit, alarm, fire extinguisher, eye wash, safety regulations and training
Attitude related causes of accidents
Lack of awareness, lack of knowledge, unsafe attitudes, errors in judgement
Factors leading to accodents
Out of control feelings
Cool off
1 Ingredients
2 physical data
3 fire and explosion hazard data
4 reactivity data
5 environmental and disposal information
6 health hazard data
7 first aid
8 handling precautions
1 eye protection
2 hearing protection
3 breathing protection
4 showers and eyelashes
5 skin protection
6 foot protection
7 head protection
8 fall protection