Midterm Exams Flashcards
Studies and manipulates the composition and structure of materials across length scales to control materials properties through synthesis and processing.
Material science & engineering
- Study the relationship between synthesis, processing, structure, and properties
of materials
Material Science
- How to translate materials into useful devices
Material Engineering
Principal materials used in the building of structures and machines
Engineering materials -
- Function, Material, Shape, Process
Material Selection Components
- Support routine information on the quality of a product. Develop new/better
information on known materials or to develop new materials
Material Testing
- Obtain/Discover new properties of materials
Material Research
- involves the idea that the outcome may be uncertain
Experiment
- involves the idea of a more or less established procedure and that the limits of the results
are generally defined
Testing
Difference lies on location of the test
Field Tests vs Laboratory Tests -
A type of test that needs to destroy the material to gather data (Compressive
test)
Destructive Test -
- A type of test that does not need to destroy the material to gather data
Nondestructive test
- Observation of the processes and products of manufacture or construction for the
purpose of ensuring the presence of desired qualities
Inspection
Design Process
a. Initial Design
b. Phase 1: External Loads (Statics & Dynamics)
c. Phase 2: Internal Loads (Mechanics of Deformable Bodies)
d. Phase 3: Material Selection (Material Testing)
e. Phase 4: Member Dimension (RCD, Steel, Timber)
f. Final Design
Focuses on determining/identifying material properties
Material Testing -
Properties that relate to the behavior of materials under the application of forces
Mechanical Properties of Materials -
- Measures by stress at which some specified limiting condition is developed
Strength
- Point where stress is proportional to strain
Proportional Limit
- Pont where, after being loaded, a member can still return to its original shape
Elastic Limit
Point where permanent deformation can be expected after a member is being loaded
Yield point -
- Highest stress on the stress-strain diagram
Ultimate strength
The stress where failure occurs
Rupture strength -
- A machine used to obtain the stress-strain diagram
Universal Testing Machine
- Ability of a material to be deformed without permanent deformation
Elasticity
- Completely recovers its original shape and dimension after the release of stress
Perfectly Elastic
- Describes the ability of a material to undergo permanent deformation without rupture
Plasticity
- Relative deformability of a material under load. Measured by rate of stress with respect
to strain
Stiffness
- Relative deformability of a material under bending load especially in the plastic range
Flexibility
- The capacity of a material to absorb/store energy
Energy Capacity
- The energy absorbed in stressing a material to the elastic limit
Elastic Resilience
- Energy lost
Hysteresis
- Involves energy required to rupture a material
Toughness
- Breakdown of an object (such as metal, concrete or plastic) due to various factors that affect the strength, stability and chemical composition of the object’s structure.
Material Failure
- Relative to a limiting condition
Micro perspective on failure
- Relative to an acceptable performance
Macro perspective on failure
3 Modes of failure
a. Slip/flow - occurs under shearing stress
b. Separation - action induced by tensile stress
c. Buckling - a phenomenon induced by compression
- Primary factor to permanent plastic deformation of materials and metals. Occurs under a given
stress
Slip
- Imperfections in the crystalline lattice
Dislocations
- An amorphous/liquid deformation of materials which can be visualized as a characteristic
between that of a crystalline and viscous liquid
Flow
- The deformation under circumstances where temperature is elevated, and material is exposed to static mechanical stress. Occurs on elevated temperatures & static load
Creep
- The actual tearing apart of a portion or the whole member
Fracture
- Shows evidences of slip which does not fracture unless there is a distinct
“necking down”. Provide signs before the actual tear.
Ductile Materials
- Shows signs of slip but they usually fracture without signs of any appreciable flow of the material. Destructive, unpredictable, sudden
Brittle Materials
- Type of load where the material either withstands or fails
Static Loading
- Type of load where the material forms a nucleus for damage and spreads until the whole member fails
Repeated Loading
- Takes place gradually and rarely causes sudden or dramatic structural damage.
Predominantly affects the economics of engineering materials through maintenance costs.
Corrosion & Wear
- The process of decay on a material caused by a chemical reaction with its environment
Corrosion
- Type of corrosion that has an even attack of oxidation across the surface of a
metal material
Uniform Corrosion
- Type of corrosion that targets a specific area in a metal’s structure
Localized Corrosion
- Type of corrosion that occurs when two dissimilar metals are in contact with
each other in the presence of an electrolyte
Galvanic Corrosion
- Type of corrosion that occurs when metals are exposed to various
environmental conditions
Environmental Corrosion
- Type of corrosion that is caused by high temperature oxidation and
carbonization
High-Temperature Corrosion
- The continuing loss of material from the surface of a solid body due to mechanical action
Mechanical Wear
Takes place when a machine or structure ceases to function properly on account of excessive deformation, yielding, cracking, or fracture. Assumed to be caused by excessive stress
Structural Damage -
Steps in Analyzing Structural Damage/Cause of Failure
a. Observation
b. Hypothesis
c. Computations
d. Verifications
- A theory of failure that states stress (singular) being the cause
of structural damage. Failure will occur when the maximum principal stress in the structure reaches
the maximum stress at the elastic limit
Maximum-Principal Stress Theory
- A theory of failure applicable for ductile materials. Failure will
occur when the magnitude of the maximum shear stress in the part exceeds the shear strength
Maximum-Shear Stress Theory
- A theory of failure applicable for brittle materials. Failure will
occur when the maximum tensile/compressive stress in the part exceeds the ultimate
tensile/compressive strength
Maximum-Normal Stress Theory
- A theory of failure that takes into account combined energy of all the combined
stresses in the damaged region is the cause of structural damage
Total-Strain Theory
- The intensity of an internal force in a body which resists external force acting on the body
Stress
What is ASTM
American society for testing materials
