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Glossary of Terms

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

A:

Accuracy

This is an expression of how close a measurement is to the actual value.  Not to be confused with precision.

Accuracy, Force Measurement

Adherence or Adhesion

The extent to which one material layer bonds to another.  This is normally seen in layers of materials such as a coating to a substrate or to laminated materials.

Adhesion Test

This test determines the level of adhesion or adherence between two layers, or the strength of adhesion between a coating and substrate material.

Analogue Ouput

An analogue output is a continuous signal, from a transducer, given usually as a voltage or a current. The output from a loadcell is an analogue one, but it is put through an analogue to digital converter so that it can be manipulated and stored in a useful form for computers.

Application Torque

The turning force, otherwise known as torque, normally measured in Ncm, required to screw a threaded closure onto a container.

Axial Strain

Axial, meaning ‘on axis’.  This is the extent of sample deformation in the direction in which the force is applied.

 


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B:

Bending Strength

The amount of force applied in a flexure test to a sample before it either breaks or cracks.  Also known as flexural strength.

Bend Test

Care should be used when using this term. It is sometimes used to mean a flexure test.  However, in metals testing for example, it can be more specific where it is used to measure a material’s ductility.

Bond Strength

The parameter that describes the stress required to separate a layer of material from the base to which it is bonded. It is sometimes known as Peel Resistance.

Break Elongation

The strain applied to a specimen at the point where it breaks.

Break Strength

Normally associated with textiles, yarns and leather samples, it is the load at which a break is detected divided by sample width.

Breaking Load

This is the load or force which causes fracture in a tensile, compression, flexure or torsion test.

Break Detection

The mechanism by which a sample break is ascertained.  In software, this is often associated with the gradient of the stress/strain curve and sensitivity to break detection can be adjusted.

(Loadcell) Bridge Resistance

The nominal electrical resistance of the loadcell circuit measured at the excitation connections of the loadcell with zero load applied to the loadcell and the output connections open circuit. Expressed in ohms (_).

Bulk Modulus of Elasticity

Ratio of stress to change in volume of a material subjected to axial loading.

Burst Strength

The ability of a material to resist rupture by pressure.

 


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C:

Calibration

The comparison of transducer output against input quantities that are traceable to international standards.  Calibration would normally be carried out by a recognised authority and should result in the issue of a calibration certificate.  If there is any change in transducer performance or damage to the transducer or if there is any unusual behaviour exhibited by the transducer, it should be recalibrated.

Capacity (of load cell)

The maximum axial load a loadcell is designed to measure within its specifications.

Certificate of Conformity (CofC)

A Certificate of Conformity (CoC) is a declaration by Mecmesin to our customer that the product conforms to our stated specifications.

CRC (Child-resistant Closure)

A closure which makes removal by a child difficult.  Usually, these are ‘push-and-twist’ or ‘squeeze-and-twist’ type caps.

Closure

Any structure or device designed to close off the opening of a container and prevent loss of its contents.

Closure Removal Torque

The turning force necessary to loosen, open, or remove a closure from its container.

Closure Torque Testing

The act of measuring the turning force required to either apply or remove a closure on a container.

Coefficient of Friction (COF)

Coefficient Of Friction is the measurement parameter that is used to describe the force required to move a sample of material against another sample.  Usually applied to plastic films, paper etc.

Compression

The application of a force, the end result of which is to reduce the sample height.  Applying pressure to a sample in order to deform or flatten it.

Compression Spring

Open-coil helical springs wound or constructed to oppose compression along the axis of wind. Generally, these coil springs are either placed over a rod or fitted inside a hole. When you put a load on a compression coil spring, making it shorter, it pushes back against the load and tries to get back to its original length. Compression springs offer resistance to linear compressing forces and are one of the most efficient energy storage devices available.

Compression Testing

The act of determining sample behavior under a crushing or compressive force.

Compressive Strength

This is the maximum stress applied to a material during a compression test.  If the material does not break during the test then the test method should specify at what point to take the measurement.

Crosshead

A stiff beam mounted on an electromechanical test stand that is driven up and down for tension & compression testing. It is connected with the sample under test via the force sensor and grips and can be moved at variable speeds producing a tensile or compressive force on the sample.

Creep

When a change in load is applied to a specimen, the new stress and/or strain reading can drift by a small amount over time. This is termed creep.

Cycling

Repetitive testing of a sample between specified force or extension limits.


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D:

Data Acquisition Rate

This is the rate at which data is collected during a measurement.  In the context of materials testing it is usually measured in kHz or Hz.  Currently Mecmesin test stands acquire data at a rate of up to 2kHz whereas our handheld gauges can sample at up to 5kHz.  When considering data acquisition rate in a test application, faster is not always better.  For example, some tests consist of slow initial changes followed by rapid increase to break.  In these cases fast acquisition early in the test merely fills disk space, but toward the break region, fast acquisition can give vital information where a slower acquisition might miss features of the stress/strain curve.

Data Filtering

The processing of data sets to exclude outliers, to eliminate noise from data, to reduce the sample data set, to average data or to isolate certain subsets of data.  This can be achieved in electronic hardware or in software.  Both Emperor and Emperor Lite software can filter down to 10Hz and when slower sample rates are selected than the default 2kHz, then intermediate points are averaged to give the sample rate selected, so for 100Hz sample rate, every set of 20 consecutive readings are averaged.  Slower sampling rates are advisable where the trend of data is required rather than the fine detail of peaks and troughs.  Hardware filtering is commonly used to reduce the effects of RF noise and vibrational noise on the load cell caused by sample break, motor noise etc.  These filters are set to eliminate frequencies above the highest sampling frequency of 2kHz.

Data Output Rate

This is the rate at which data is transmitted from device to PC.  Not to be confused with baud rate in the RS232 settings or data acquisition rate.  Data output rate often depends upon how fast the CPU can prepare data for transmission.  Eg.  Because of all the background computational and administrative tasks being executed by the on board processor, the AFG handheld force gauge transmits 10 readings every second although the baud rate might be set to 115,200bps and the acquisition rate is 5kHz.  So here, the data output rate is 10Hz.  Data acquisition rate is still 5kHz to enable accurate peak detection.

Daylight

This is the dimension, on a test stand, measured between the anvil plate and crosshead. Effective daylight is the same dimension, but with the loadcell fitted. Other things that effect the daylight are: grips/fixtures on both the anvil plate and loadcell. We quote effective daylight for all of our stands with a loadcell fitted onto the crosshead, but no fixtures on the anvil plate.

Deflection

The degree to which a structural element is displaced under a load.  In Mecmesin systems this is measured from the crosshead position as standard, but where more accurate measurement of deflection is required an extensometer should be used.

Deformation

A change in the dimensions of a material under stress or strain.

Delamination Force

Using a peel test, this is the force required to separate two bonded materials.

Delamination Strength

Using a peel test, this is the force required to separate two bonded materials divided by the sample width.

Displacement

The total driven movement of a test stand. Linear displacement is usually measured in millimetres or inches, whereas rotary displacement is usually measured in revolutions (revs) or degrees. Note that displacement may differ from specimen deformation.

Display Update Rate

The frequency at which a display is refreshed with a new reading.  This is not the same as data acquisition rate, data output rate or peak capture rate.  Mecmesin force and torque gauges are set to refresh the display at approximately 8Hz, which is considered comfortable for the eye to follow.  This has no effect on data acquisition rate or data output rate.

Ductility

The amount of plastic deformation exhibited by a material before it ruptures.

Dynamic Force

In door closing applications: This is the maximum force observed within the time interval. It provides an estimate of the maximum rate at which the kinetic energy, developed by the closing door, is released during the closing operation.

Dynamic Time

In door closing applications: This is an estimate of the duration of the event, which leads to the peak load being observed. In the cimplest case, i.e. when the door does not 'bounce' significantly, it is the time interval between the load passing through 150N on the way up to the peak and the load falling below 150N on the way down from the peak. (However, if the load oscillates, then it is the time interval between the load passing through 150N on the way up to the peak and, within a time period 0.75s, the final time that load falls below 150N.)


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E:

Eccentricity

The difference between the direction of load application to the true axial direction.

Elastic/Elasticity

A material is said to be elastic if it deforms under stress (e.g., external forces), but then returns to its original shape when the stress is removed. The amount of deformation is called the strain. Elasticity is the ability of a material to return to it’s original dimensions subsequent to the application of stress or strain.  The linear portion of the stress/strain curve of a Hookean material is called the elastic region because if applied force is removed within this region, the material will return to it’s original shape and size.

Elastic Limit

This is the stress value during a tensile or compression test after which the sample suffers permanent deformation.  For Hookean materials, it is roughly equal to the limit of proportionality (LOP).

Elmendorf

A technique used to measure the tearing resistance of a material.  The test method and form of sample preparation are described in ASTM D1922, ASTM D1424, ISO 6383, ISO 1974 and TAPPI T414 standards.

Elongation

The permanent extension of a specimen which has been stretched to rupture in a tension test.  Test Results are reported as the ratio of final length and original length.

Energy

The work done on a sample during a tensile or compression test.  It is calculated as the area under the stress/strain curve and is measured in Joules, the SI derived unit for energy.

Extension Spring

Extension springs are attached at both ends to other components. When these components move apart, the spring tries to bring them together again. Extension springs absorb and store energy as well as create a resistance to a pulling force. Extension Springs are wound to oppose extension. They are often tightly wound in the no-load position and have hooks, eyes, or other interface geometry at the ends to attach to the components they connect. They are frequently used to provide return force to components that extend in the actuated position..

Extrinsic

Extrinsic properties are characteristics of a test specimen as a whole, rather than the material from which it is made. Examples of extrinsic properties are: mass, volume.  Opposite of intrinsic, examples of which include: temperature, density, melting point.


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F:

Final Force

In door closing applications: The value of force measured at 5 secs.

Flexural Bond Strength

Stress developed in an adhesive bond between two materials determined in a flexure test.

Flexural Strength

The maximum stress developed in a specimen just before it ruptures in a flexure test.

Flexure Test (Bend Test)

3-point Bend Test, Flexure Test, Bend Test, Compression Test, 3-Point Flex Test

4-Point Bend Test, Flexure Test, Compression Test, 4-point Flex Test

 

 

 

 

 

 

               3-point Flex Test                                                      4-point Flex Test

A test where a sample is supported at both ends and a compressive force is applied to the middle of the sample.  Also known as a Bending Test.  This can be done as a three-point or four-point test:

Force

The classic definition of force is any action which alters or tends to alter a body’s state of rest or of uniform motion in a straight line.  Force has both magnitude and direction, making it a vector quantity. Newton's second law states that an object with a constant mass will accelerate in proportion to the net force acting upon and in inverse proportion to its mass. Equivalently, the net force on an object equals the rate at which its momentum changes.  Force is measured in Newtons, which is an SI derived unit.  1N is the force required to accelerate 1kg to 1ms-2. Forces acting on three-dimensional objects may also cause them to rotate or deform, or result in a change in pressure and/or volume in some cases. The tendency of a force to cause changes in rotational speed about an axis is called torque.

Frequency

The number of times an event occurs per unit time.  Rate.  Measured in Hertz (Hz), Kilohertz (kHz) or megahertz (MHz).

Frequency Response

This is the ability of a system output to replicate the input. Most electrical systems have limited frequency response (bandwidth) which allows the elimination of noise from the measurement.  It is important for a system to have a bandwidth sufficient to capture significant events of the test, for example, details at sample break.  Mecmesin Emperor driven systems have a sampling frequency of 2000Hz, which means that a reading is taken every 0.5milliseconds.

Full Scale (FSD)

This is the capacity of a sensor, in this context, the load measurement system or load cell.  FSD stands for Full Scale Deflection and is derived from old analogue displays which used a needle against a background scale.


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G:

Gauge Length

Used to calculate elongation. This is often stated in industry standards as the distance between the grips on a universal testing machine.

Grips

A mechanical device that grasps and holds the test specimen. Mecmesin grips include mechanical, pneumatic, vice grips, textile attachments and specialist fixtures.


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H:

Headroom

This is the same as effective daylight. The dimension from anvil plate to crosshead with loadcell fitted.

Hooke’s Law

Assuming perfectly elastic behaviour, stress is linearly related to strain:  Robert Hooke, in the 17th century, stated “As the extension, so the force”.  F=-kx, where x is the displacement, F is the restoring force required and k is the force, or spring constant.  Materials that exhibit near ideal elastic behaviour are sometimes called ‘Hookean’ materials.

Hysteresis

When a material is cycled from zero stress to a peak stress and then back to zero again, the stress/strain curve follows a closed loop.  This is because the material does not have perfect elasticity and is slightly stretched on the ‘up’ stroke.  The maximum difference between stress on the upward and downward strokes of the cycle is quoted as the hysteresis, normally in terms of %FSD.

Hysteresis, Materials Testing


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I:

ILC

An Intelligent Loadcell (ILC) is a force or torque sensor specially designed for operation with Mecmesin Emperor and MultiTest-i test stand. It incorporates a memory chip that stores both calibration data, and details of operational service (including overload history.)

Interpolation

A mathematical method of estimating a value that falls between two data points.  Linear interpolation is the most common form where a simple estimation is made by drawing a straight line between the two data points.

Intelligent Loadcell

Mecmesin loadcells, ILC and XLC are designated 'intelligent' loadcells for the fact that they have on-board electronics that perform loadcel deflection compensation and, in the case of the ILC, other data handling functions.

Intrinsic

The fundamental properties of a material.  Melting point, density, heat capacity etc…


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J:

Jog Key

The key, or control button on a test stand or control panel that enables manual movement of the crosshead at a factory set speed.  Not normally latched ie. Only operates while the button is pressed.

Joule

The SI derived unit of work, energy and heat. It is the work done when a force of one newton moves through a distance of 1 metre.  The area under a stress/strain curve gives the measurement of work done on a sample during a test.


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K:

Kilogram Force (kgf )

The 'kilogram force' is 9.80665 newtons. The practise of expressing force in kgf arose from the historical confusion which existed between ‘mass’ and that particular force with which we are all familiar and which we refer to as ‘weight’. Although not adopted as a unit by the International System of Units (SI), kgf may be defined as ‘the force that produces an acceleration of 9.80665 metre per second per second* on a mass of one kilogram’. A kgf may sometimes be written as 'kp' and referred to as a 'kilopond'.

(* This is the internationally adopted value of the acceleration due to gravity.)

Kinetic / Dynamic Friction

The average force required to maintain movement of one material against another.

Kilopascal (kPa)

The SI derived unit of pressure and stress is the Pascal (force per unit area:  1Pa = 1N/m2). The ‘kilopascal’ is 1000 N/m2 or 1mN/mm2.


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L:

lbf

The true imperial unit of force is the poundal (the force that produces an acceleration of one foot per second per second on a mass of one pound), but this is no longer used.  Instead the term ‘pound force’ is in widespread use and is a curious mixture of imperial and metric measurements. One lbf is about 4.44822N, the force required to accelerate 1 pound by 9.80665ms-2.

Limits (Upper and Lower)

A safety feature on Mecmesin test frames that stop the test frame when the upper or lower limit is reached.  Correct setting of the operational limits will reduce the risk of damage to the test frame, the loadcell, and the operator.

Load

An alternative term to mean force.  The two are used interchangeably.

Loadcell

The transducer used in Mecmesin Universal testing machines.  Loadcells are based on strain gauge technology.  This is a tried and tested method of measuring force using a change in electrical resistance brought about by dimensional changes in a metal block caused by increasing and decreasing force.

Loadcell Deflection Compensation

A loadcell, by definition and design is made from a material which deflects when acted upon by a tensile or compressive force.  This must be compensated for when calculating the distance travelled by the crosshead during a test.  All Mecmesin test stand load cells (ILC’s and XLC’s) have been characterized and their deflection compensated for when reporting crosshead displacement.

Load at Yield

The load reported at the point at which a specified deviation from proportionality of stress and strain occurs.

LOP (Limit of Proportionality)

This is the point on the stress/strain curve beyond which the stress does not increase proportionally with strain.


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M:

Major Span

This is the distance between the lower supports in a bend, or flexure test.  See diagram here.

Maximum Load/Force

The highest load in a specific test or application, which may be any load up to and including capacity plus minimum load, but must not exceed capacity significantly.  Sometimes denoted as ‘Fm’, ‘Fmax’, ‘Rm’.

Mean Force

The sum of all force data divided by the number of data points.

Measuring Range

The difference between maximum load and minimum load in a specific test or application. It must not exceed load cell capacity.

Median Force

This is the central value in a group of values, when placed in order.  If there is an even number of values, then the median is halfway between the two central values.

Minimum Load

The lowest load in a specific test or application.  This is not necessarily zero load, but includes the weight of any fixtures which are attached plus any intentional pre-load which is applied.

Minor Span

This is the distance between the upper supports in a 4 point bend, or flexure test. See diagram here.

Modulus of Elasticity

Rate of change of strain as a function of stress.  The slope line portion of a stress-strain diagram.

MPa

The SI derived unit of stress is the Pascal (one newton per square metre). The ‘megapascal’ is one newton per square millimetre.


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N:

Necking

Narrowing of a sample as tensile load on it is increased.  Associated with plastic (permanent) deformation.

Newton

The SI derived unit of force is the newton (the force that produces an acceleration of one metre per second per second on a mass of 1 kilogram).

Nonlinearity

Non-linearity can be evaluated for either an individual data point or for a measurement run.

For an individual point it is the difference between measured output at a specific load and the corresponding point on the straight line fit to the output data. Normally expressed in units of %FSD.

The non-linearity for a measurement is usually defined as the maximum deviation between the measured output and straight line fit to the output data.  This can be expressed in terms of the measurement units or %FSD.

Nonlinearity, Force Measurement, Force Testing

Nonrepeatability

Sometimes used to mean the same as repeatability.


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O:

Offset Yield Strength

Arbitrary approximation of elastic limit. Used where a sample stress-strain curve has no discernable yield point.  It is the stress that corresponds to the point of intersection of a Stress-Strain Diagram and a line parallel to the straight line portion of the diagram. Offset refers to the distance between the origin of the Stress-Strain Diagram, and the point of intersection of the parallel line and the 0 stress axis. Offset is expressed in terms of strain and depends upon the material (for metals it is often 0.2%, for plastics it tends to be 2%).

Offset Yield Strength, Materials Testing, Elasticity

Output

The system response to an input.  For a calibrated force measurement system, accurate output is the arithmetic difference between zero load and the current reading.

Overload

Applying a force that exceeds the capacity of the loadcell. Repeated overload, or significant overload can damage the loadcell and require a recalibration or replacement. It is important to ensure that there is headroom built into your system i.e. use a loadcell that has a capacity of approximately 120% of the expected maximum load.


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P:

Peak Capture Rate

The sampling rate at which the peak force is captured.  This can be different from the test sample rate.  All Mecmesin devices sample at the highest rate.  This data is then filtered either on-board to the output rate for portable gauges or in software to the specified sampling rate in Emperor.  The peak force reported on gauges is always captured at the maximum rate.

Peak Force

The point of maximum force.

Peel Resistance

Another name for Bond Strength.

Precision

The expression of how close multiple measurements of the same quantity are to each other.  Not to be confused with accuracy.

Precision, Force Measurement

Pretension

A term associated with either a tension, compression or torque force applied before testing begins.  Sometimes it is a ‘touch’ to the sample, but other times it may be a more significant force.  May be tared out of the measurement so that a group of sample tests may all be compared easily.

psi

'Pounds per square inch', the imperial unit of stress.


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Q:


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R:

Removal Torque

The torque force, usually measured in N.m, required to unscrew a closure from a container.

Repeatability

The closeness of agreement between independent results obtained with the same method on identical test material, under the same conditions (same operator, same apparatus, same laboratory and after short intervals of time).  Traditionally, repeatability is expressed as the standard deviation of results from repeated measurements of loadings under identical loading and environmental conditions using the same operator. When using this method, quoting 2 times the standard deviation gives approximately 95% confidence.  Sometimes the maximum difference between output readings is used.  Normally expressed in units of %RO or %FSD.

In some contexts repeatability may be defined as the value below which the absolute difference between two single test results obtained under the above conditions, may be expected to lie with a specified probability.

Reproducibility

Reproducibility, although similar, should not be confused with repeatability.  It is the closeness of agreement between independent results obtained with the same method on identical test material, under the same conditions but with different operators.

Resolution

The resolution corresponds to the smallest two digits / values which can be read from a measurement device. Resolution should in no way be confused with Accuracy.

RS232

A serial communication standard in use since 1969.  PC’s adopted the standard in order to enable communication with existing devices.  Now becoming unavailable on some modern PCs due to the introduction of USB, which is faster.  It is the current preferred method of connecting Mecmesin test equipment to a PC, mainly due to the reliability of RS232.  A USB adapter is provided with all instrumentation and stands for use where an RS232 port is unavailable.

Rupture

Term describing the moment when a sample bursts or is torn.


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S:

Scragging

This is a term used in the spring industry to mean the presetting or pre-conditioning of a spring.  For a compression spring, the sample is compressed to a ‘solid’ a number of times prior to testing.

Sample Break

The point at which a specimen breaks or fractures.

Shear

A force acting perpendicular to the longitudinal axis of the sample.

Shear Modulus

This is the tangent or secant modulus of elasticity of a material when subjected to a twisting force.  Sometimes equal to the torsional modulus of elasticity.

SI Unit

In 1960, the Système International d'Unités was introduced to replace systems of units based upon the metre/kilogram/second (mks), the centimetre/gram/second (cgs) and the foot/pound/second (fps). It is based on seven basic units:

Length - metre (m)
Mass -   kilogram (kg)
Time -    second (s)
Electrical current - ampere (A)
Temperature - kelvin (K)
Amount of a substance - mole (mol)
Luminosity - candela (cd)

All other measurement units can be derived by a combination of these basic units.

Signal

The absolute level of the measurable quantity into which a force input has been converted.  Normally expressed as a displacement (as in a dial-type force gauge), or a voltage or current in electrical gauges and load cells.

Sled / Sled Weight

The sled is the moving element used in a friction test.  The term weight here is used to mean ‘mass’ of the sled.  For standard test methods, the mass of the sled is normally required to be within limits.

'Smart' Sensor

Mecmesin product designed for use with the Mecmesin Advanced Force Gauge or the AFTI. A Mecmesin smart transducer is a plug and play interchangeable transducer that can be used with no recalibration of sensor or display. Force and Torque versions are available.

Standard Deviation

This is the root mean square deviation from the mean of a random distribution.

Standard Uncertainty

A component of uncertainty in a measurement, expressed as a standard deviation s.

All components of an uncertainty will be combined to form the uncertainty of measurement as quoted on a calibration certificate.

Static Force

In door closing applications: This is the average force from the end of dynamic time until data acquisition stops i.e. at 6s.

Static Friction

The maximum (peak) force required to initiate movement of a material.

Stiffness

The ability of a test specimen to resist deforming in response to an applied load is called stiffness, i.e. stiffness is the gradient of a load / deformation curve. When testing a spring, stiffness is usually referred to as ‘spring rate’.

The gradient of a stress / strain curve is usually referred to as ‘elastic modulus’ or, in the specific case of deflection occurring in the same direction as the applied load, ‘Young’s modulus’. Emperor can calculate stiffness values by means of the SLOPE or BEST-FIT commands.

The reciprocal of stiffness is called 'compliance'.

Stiction

Aka Static Friction.

Strain

Usually used to denote the engineering strain.  Quantitatively, it is the change in length of a specimen (as a result of an applied load) divided by the original length of the specimen; it is usually expressed as a percentage.

Strain Gauge

A device with electrical resistance that is a function of the applied strain. Normally in a Wheatstone bridge configuration.

Stress

Usually used to denote the engineering stress.  It is the load applied to a specimen, divided by the cross-sectional area of the specimen. Pressure.  Can be measured in N/mm2, N/m2, psi, MPa or kPa.

Stripping Torque

The amount of application torque that causes the threads of the closure to override the container threads.

Stroke

In a tension or compression test, a stroke is one portion of the test movement, either an up or down movement of the crosshead. Sometimes referred to in machine specifications to mean the total available crosshead movement.


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T:

Tack Test

Applicable to adhesives. Two surfaces are contacted together at a set speed for a set duration and the force required to pull them apart is recorded.

Tamper-evident Closure

A closure or liner system incorporating a feature that visually indicates if the closure has been removed or the product has been exposed. Removal of the closure or liner system activates the indicating feature.

Tare

To automatically subtract either the weight of a container, fixture or specimen, or the residual force being exerted by the specimen. Subsequent readings correspond either to the weight of the contents of a container, or to the force being exerted (via the fixturing) by a specimen under tensile or compressive load.

Tear Strength

The force required to tear a sample divided by the sample thickness.

Temperature Range, Compensated

The range of temperature over which the LOAD CELL is compensated to maintain OUTPUT and ZERO BALANCE within specified limits.

Temperature Range, Operating

The extremes of AMBIENT TEMPERATURE within which the LOAD CELL will operate without permanent adverse change to any of its performance characteristics.

Tension

A force tending to stretch or elongate a specimen or material.

Tensile Strength

The ultimate strength of a material subjected to tensile loading. It is the maximum stress developed in a material during a tensile test.

Tensile Strength, Tensile Testing, Tensile Loading

Tensile Test

A tensile test is a way of determining how something will react when it is being pulled apart, or more correctly, when a force is applied to it in tension.  Also known as a Pull Test.

Test Type

Examples of test types include Coefficient of Friction, Compression, Burst, Peel, 3 Point Bend, Tear and Tension.

Texture

In food testing, sometimes called mouth feel, and is the physical interaction that food has in the mouth during the chewing process. This can sometimes also be the interpreted by finger feel.

Throat Depth

This is the dimension of available throat depth for the test specimen, from the axis of the loadcell to the machine.

Tolerance

The permissible maximum deviation from specified dimensions, quantities, or specifications. The amount of variation allowed from the nominal dimension.

Top-load

The force bearing on the top of a specimen.  Often a test used to measure packaging that is stacked in storage.

Torque

A twisting effect, or moment, exerted by a force acting at a distance on a body, equal to the force multiplied by the perpendicular distance between the line of action of the force and the center of rotation at which it is exerted.

Torque is often expressed in the following units of measurement: N.m, Kgf.m, kgf.cm, lbf.ft, lbf.in

Torsion Test

Method for determining behavior of materials subjected to twisting loads. Shear properties are often determined in a torsion test. (ASTM E-143).

Torsional Modulus

AKA torsional modulus of elasticity, it is usually equal to the shear modulus.  It is the modulus of elasticity of a material subjected to a twisting force.

TPA (Texture Profile Analysis)

In food testing:  a two bite test that imitates the action of chewing. From the results, a number of sensory related parameters can be determined.

Traceability

Traceability is the property of a measured result or value of a standard, whereby it can be related to stated references, usually national or international primary or secondary standards, through an unbroken chain of comparisons and all having stated uncertainties.

True Strain

This differs from engineering strain in that it is determined from the rate of change in gauge length with respect to the instantaneous gauge length.  It is expressed as a natural logarithm of engineering strain.

True Stress

True stress is the load divided by the instantaneous area of the specimen.


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U:

Ultimate Elongation

This is the amount of elongation suffered by a specimen, or material, at rupture under tensile loading.

Ultimate Strength

Highest engineering stress developed in material during a test and prior to rupture, or break. Normally, changes in area due to changing load and Necking are disregarded in determining ultimate strength.

USB

Universal Serial Bus, now USB2.0. It is an interface available on modern PCs.  It is one way of connecting a PC to the test stand, RS232 is the other. Mecmesin stands all communicate using RS232 but are supplied with a USB adapter.


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V:

Verification

The act of testing a device against recognized standards.  Different from calibration in that there is no adjustment of the device to meet the standards.  Verification results in a pass or fail.


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W:

Wet Strength

Breaking strength of paper saturated with water. This term can also be used to describe the strength of an adhesive bond after immersion in water.


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X:

XLC

Mecmesin intelligent loadcell, for use with the range of console driven test stands.


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Y:

Yield Point / Yield Strength

The point during a tensile test when a specimen ends elastic deformation and begins plastic deformation.  There is an increase in strain with no corresponding increase in stress

Yield Strength is an indication of maximum stress that can be developed in a material without causing plastic deformation. It is the stress at which a material exhibits a specified permanent deformation and is a practical approximation of elastic limit.

Yield Strength, Yield Point, Elastic Deformation, Plastic Deformation, Materials Testing

Young's Modulus

Hooke's law states:

F = -kx

where F is the restorative force, x is the displacement and k is a force (or spring) constant. Put another way,

E =  stress/strain

stress is the force applied to the specimen and strain is the relative elongation of the specimen from it's original length. E is known as Young's Modulus, represented as the gradient of the stress-strain curve within the initial linear region.


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Z:

Zero Offset

The difference between true zero and an indication given by a measuring instrument under zero input conditions.

Ductility

The amount of plastic deformation exhibited by a material before it ruptures.