B259
OTHER:
Composite - Definitions|
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These definitions will apply to most all materials.
Note: The algorithms are in blue.
Outside Web Sites:
Dictionary of Composite Materials Technology
Allowable Stress:
The exact number of pounds that can be carried by a piece of material having a 1" cross-section without failing.
Band:
The collection of all the tapes in a single layer. The torque tube has 2 tapes per band. ~ This is my thinking only
Bias:
A condition in fabric which can result from the angular displacement of filling yarns or knitted courses from a line perpendicular to the edge of the fabric.
Also see; Wind Angle.
Breakout Board: (CNC)
A board that usually plugs into the parallel port and usually has connections for stepper drives, home and limit switches, and relays. It makes it easier to wire everything up to the computer.
Coefficient of Thermal Expansion: [CTE] or [ά] alpha
The fractional change in length of a material per degree of temperature change as compared to its length at a reference temperature.
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Compressive Ultimate Strength: [Scu]
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Compressive Yeild Strength: [Scy]
Maximum material strength under compressive loading.
Creel:
The spool and its supporting structure on which continuous strands or rovings of reinforcing material are wound; used in the filament winding process.
Density: [ρ] rho
The mass per unit volume of a solid material, usually expressed in pounds per cubic inch or grams per cubic centimeter.
Doctor Bar (Doctor Blade):
A flat bar used for regulating the amount of liquid material on the rollers of a coating machine, or to control the thickness of a coating after it has been applied to a substrate. Also known
Elastic Limit:
The maximum stress to which a test specimen may be subjected and still return to its original length upon release of the load.
Elastic Region:
Where the working stress does not exceed the elastic limit.
Elongation: [δ] delta
The ratio, expressed in percent, of the change in length divided by the original length of a tested test bar. The original gage length should always be included when discussing elongation.
Factors of Safety:
See Machinery's Handbook 25, page 197.
Fatigue Properties:
The maximum stress that can be applied repeatedly for a specified number of cycles without producing fracture. For copper alloys, fatigue strength is defined as the maximum stress without failure after 100 million cycles of reverse bending (r= -1).
See Machinery's Handbook 25, page 194.
Fiberglass:
Fill:
The threads that run the width of the roll or bolt and perpendicular to the warp threads.
Filament winding is a continuous, automated fabrication method that can be highly automated and repeatable with relatively low material costs. A long, cylindrical tool called a mandrel is suspended horizontally between end supports, while the "head" - the fiber application instrument - moves back and forth along the length of the mandrel as it rotates on the horizontal axis, placing fiber onto the tool in a predetermined configuration. For more description see; http://www.compositesworld.com/sb/ov-winding, http://www.mccleananderson.com/resources/whatisfilamentwinding.htm. For intended machine see; OTHER: Composite - Special Tool - CNC Work Bench &/or OTHER: Composite - Special Tool - Filament Winder
Force:
[F]A push or a pull.
Forces:
A force within an object that tries to prevent any outside force changing its shape.
Tension:
Compression:
Shear:
A deformation, or physical change, in a material caused by a stress. Is directly proportional to stress until the elastic limit of the material is reached.
Normal:
Shear:
Hardness:
A measure of the resistance of a material to surface indentation or abrasion; may be thought of as a function of the stress required to produce some specified type of surface deformation. There is no absolute scale for hardness; therefore, to express hardness quantitatively, each type of test has its own scale of arbitrarily defined hardness. Indentation hardness can be measured by Brinell, Rockwell, Vickers, Knoop, and Scleroscope hardness tests.
Winds which occur at a configurable angle along a cylindrical part. Typically used for winding all manner of pipes and shafts.
Joggles:
A small offset near the end of a sheet.
Load: [P] (lbs)
The gross or total amount of force that is applied.
Load Direction:
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Material Strength:
The maximum stress (tensile. compressive or shear) that can be sustained by the composite material: or. because of the near linear relationship between composite stress and strain. the strain level existing, under the maximum stress condition.
Metal Matrix Composite:
A composite material in which one constituent is a metal or alloy forming at least one percolating network. The other constituent is embedded in this metal matrix and usually serves as reinforcement.
A parameter characterizing the stiffness of a material, or its resistance to deformation under
stress. For example, steel has a fairly high modulus, while Jell-O has a low modulus. It is the ratio of change in stress to change in strain below the elastic limit of a material. Also referred to as Young's Modulus.The figure used for modulus is literally the unit stress in pounds per square inch, which would make a piece of the material stretch elastically to twice its original length.
Modulus of elasticity: The proportional constant between stress and strain for material with linear elastic behavior: calculated as stress divided by strain. Modulus of elasticity can be interpreted as the slope of the stress-strain graph. It is usually denoted as E, sometimes known as Young's Modulus Y, or E-Modulus.
Also known as Young's modulus, it is the rate of change of unit tensile or compressive stress with respect to unit tensile or compressive strain for the condition of uniaxial stress within the proportional limit. For most, but not all materials, the modulus of elasticity is the same for tension and compression. Is used as a measure of a materials stiffness. For values see Machinery's Handbook 25, page 193.
E is the Elastic modulus (or Strength??)
Elastic Modulus [E] = Stress [S]
/ Elastic Strain [ε]Modulus of Elasticity in Shear:
[G]The ratio of unit stress to unit strain within the proportional limit of a material in shear.
Plastic Region:
Where the working stress does exceed the elastic limit.
Ply:
As applied to laminates the layers of fiber or reinforcements.
Poisson's Ratio:
[v] (Nu)The ratio of lateral unit strain to longitudinal unit strain under the condition of uniform and uniaxial longitudinal stress within the proportional limit.
The absolute ratios of the transverse strains to the axial strain (below the proportional limit) for a condition of uniform axial stress.
A measure of the simultaneous change in elongation and in cross-sectional area within the elastic range during a tensile or compressive test. During a tensile test, the reduction in cross-sectional area is proportional to the increase in length in the elastic range by a dimensionless factor, Poisson's ratio.
Units: Dimensionless
Poisson's ratio
[v] (Nu in Greek) is the negative of the ratio of the lateral strain to uniaxial strain, in axial loading. Its value for many solids, is close to 1/3. For elastomers it is just under 0.5. For values see Machinery's Handbook 25, page 193. :This is a term in Composite Designer. A wind in which the filaments pass tangent to the polar opening at one end of the chamber and tangent to the opposite side of the polar opening at the other end. This is very close to a zero degree wind.
The point on a stress-strain curve at which it begins to deviate from a straight line relationship between stress and strain.
Quill:
The straight extension of a band at the tip end. It is used to transmit the torque to the blade tip. ~ This is my thinking only
Router: (CNC)
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Section Modulus [Z]
A physical property of strength of a structural member. It relates bending moment and maximum bending stress within the elastic range. Formula: Z = I/c where [I] is the moment of inertia of the cross-section about the neutral axis in inches^4 and [c] is the distance from the neutral axis to the outermost fibers.
To calculate values for standard shapes run program: Engineering Power Tools ~ Mechanical ~ Moment of Inertia or FORM: Rotor - Blade - Spar ~ UniCopter.
Shear Modulus:
The ratio of shear stress to the corresponding shear strain for shear stresses below the proportional limit of the material. Also referred to as Modulus of Rigidity.
The ratio of stress to strain below the proportional limit for shear.
Shear Ultimate Strength: [Ssu]
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Shear Yeild Strength: [Ssy]
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Spindle: (CNC)
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Standard Deviation:
The square root of the average of the squared deviations of scores from their mean. s=ˆ...(Xi-Xbared)2/N, where s is the standard deviation and (...Xi-Xbared) is the variance.
Strength: -
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Strength Direction:
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A measure of the relative change in the size of a body. Linear strain is the change per unit length of a linear dimension. True (or natural) strain is the natural logarithm of the ratio of the length at the moment of observation to the original gauge length. Shearing strain is the change in angle (expressed in radians) between two reference lines originally at right angles. When the term is used alone, it usually refers to linear strain in the direction of the applied stress.
A measure of the change in the size or shape of a body, referred to its original size or shape. Linear strain is the change per unit length of a linear dimension. True strain (or natural strain) is the natural logarithm of the ratio of the length at the moment of observation to the original gauge length. Conventional strain is the linear strain referred to the original gauge length. Shearing strain (or shear strain) is the change in angle (expressed in radians) between two lines originally at right angles. When the term strain is used alone it usually refers to the linear strain in the direction of the applied stress.
Deformation produced on a body by an outside force.
Change in length of an object in response to an applied stress, divided by undistorted length.
Elastic Strain [epsilon] = Extension [deltaL] / Original Gage Length [L]
Force per unit area. A measure of the intensity of the force acting on a definite plane passing through a given point. The perpendicular and parallel stresses acting on the plane are the normal and shear stresses, respectively. Also said to be the force acting across a unit area in a solid material in resisting the separation, compacting, or sliding that tends to be induced by external forces. A force within an object that tries to prevent any outside force changing its shape. Not scalar - it has a vector.
True stress denotes stress determined by measuring force and area at the same time. Conventional stress, as applied to tension and compression tests, is force divided by original area. Nominal stress is stress computed by simple elasticity formula.
Force per unit area, often thought of as force acting through a small area within a plane. It can be divided into components, normal and parallel to the plane, called normal stress and shear stress, receptively. True stress denotes the stress where force and area are measured at the same time. Conventional stress, as applied to tension and compression tests, is force decided by the original gauge length. Shearing strain (or shear strain) is the change in angle (expressed in radians) between two lines originally at right angles. When the term strain is used alone it usually refers to the linear strain in the direction of the applied stress.
Deforming force to which a body is subjected, or, the resistance which the body offers to deformation by the force.
Stress [S]or[F] = Load [P]/ Cross-sectional Area [A]
~ Tension (Tensile Stress):
A stress that causes an elastic body to elongate in the direction of the applied force.
~ Compression (Compressive Stress):
A stress that causes an elastic body to shorten in the direction of the applied force.
~ Shear (Shearing Stress):
A stress in which the material on one side of a surface pushes on the material on the other side of the surface with a force parallel to the surface (normal to the area being considered).
To calculate values for standard shapes run program: Engineering Power Tools ~ Mechanical ~ Stress & Deflection - Beams.
A group of tows that are laid side-by-side and received identical windings. This is similar to unidirectional tape except that the individual tows may be shifted in respect to each other, just as a parallelogram is a shifted rectangle. A straight tube can be wrapped with unidirectional tape but a tapered tube must have each filament laid down individually. ~ This is my thinking only
Tensile:
of undergoing or exerting tension. Capable of being stretched.
Tensile Modulus:
See Modulus of Elasticity and Young's Modulus
Tensile Strength, Ultimate Strength: [Su]
The stress at which a material will fail or break in tension. In tensile testing, the ratio of maximum load to original cross-sectional area. The maximum stress value obtained on a stress-strain curve. The maximum stress a material subjected to a stretching load can withstand without breaking.
The stress at which a material has plastically deformed (elongated) a predetermined amount. This amount is arbitrarily set at 0.2% strain.
Thermal Conductivity:
Thermoplastic Composites:
High-performance fiber-reinforced thermoplastic composites are a recent advance in engineering materials. The thermoplastic matrices include nylons, terephthalates, polypropylene and PEEK which can be reinforced with glass, carbon and aramid fibers. The advantages compared to thermoset-matrix composites are unlimited shelf life, faster production and recycling of scrap.
Tow:
The bundle of individual carbon filaments used to weave carbon fabric. 50k tow means there are 48-50,000 carbon filaments in the tow. Smaller tow i.e. 12k, 6k, 3k and 1k are obtained by dividing the 50k tow into smaller bundles.
Continuous fiber pre-impregnated with resin - also can be wound, eliminating the need for an on-site resin bath. Rollers are usually used to filament wind with towpreg to prevent damage to the material.
Ultimate Tensile Strain:
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Used to describe forces, stresses or strength as well as loads
Tension -
Compression -
Shear - To cut by causing parts to slide over each other.
Bearing -
Bending -
Warp:
The threads that run the length of the roll or bolt and perpendicular to the fill threads.
Wind Angle:
The angular measurement between the direction parallel to the filaments and an established reference. In filament wound structures this is the center of rotation (X-axis).
Wrap:
One trip around the circumference (360º). The A-axis ~ This is my thinking only.
Yield Point:
A point on the stress-strain curve at which there is a sudden increase in strain without a corresponding increase in stress. For values see Machinery's Handbook 25, page 193.
Yield Strength: [Sy]
The maximum stress that can be applied without permanent deformation of the test specimen.
Young's Modulus:
Units: SI: GPa; cgs: 1010dyne/cm2; Imperial: 106psi
Young's modulus, E , is the slope of the initial, linear-elastic part of the stress-strain curve in tension or compression. For isotropic materials it is related to the bulk modulus K and to the shear modulus G by
E = 3(1 - 2v)K
E = 2(1 + v)G
where v (Nu in Greek) is Poisson's ratio. Commonly v = 1/3, and hence E = K, and E = (8/3)G.
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Last Revised: April 24, 2007