Zwick Materials Testing - manufacturer of materials testing machines

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A	Description
Accuracy	The measure of the correctness of data,t as given by the difference between the measured value and the true or standard value. Accuracy is not the same as resolution, but resolution is typically <0.5 of the stated accuracy.
Adhesion Test	The adhesion test determines the strength of adhesion between two layers, or the strength of adhesion between a cover layer and substrate material.
Alignment	Central and axial installation of a load cell and mounting studs. This is vitally important for most materials. It is also a principal measure of the quality of the testing machine. The load frame / gripping system must not distort during the test causing poor alignment. See also Nadcap.
Auto Return	Automatically returns the crosshead to the original start position at the end of each test. Also known as LE position within certain international standards.
Autoscale	Auto scaling may be set individually on the x or y axis to resize the graph screen automatically. TestXpert has a software switch within each test definition so that the operator may choose which mode they prefer.
Auxiliary Device	Auxiliary or external devices are items that are attached to either the PC running testXpert, or the testing machine. Such devices are Extensometers, Balances, Thickness Gauges, cross section monitors etc.
B	Description
Balance	An instrument for measuring the specimen weight. Many of these items can be connected to Zwick machines for automatic transfer of data to testXpert.
Bending Test	The three point bending flexural test provides values for the modulus of elasticity in bending, flexural stress, flexural strain and the flexural stress-strain response of the material. The main advantage of a three point flexural test is the ease of the specimen preparation and testing.
Block force	Force at which a spring is detected as being blocked. This is the minimum force achieve for no more deflection in the spring (All individual coils are pressed together).
Block height	Height of a spring at which it is blocked.
Breadth	The measure or dimension of the test sample from side to side. Also known as width.
Brittle fracture	Brittle fracture occurs with little or no plastic deformation within the component. Brittle fracture often results in catastrophic failure. Brittle fracture is influenced by defects, fatigue, and stress-corrosion.
Brugger Test	To the present day there is no common standardized process for testing the toughness and hardenability of case-hardened steel. Decades ago, the former Zahnradfabrik Friedrichshafen - cogwheel factory Friedrichshafen, in Germany, developed a process with which these parameters were tested for the release of the corresponding molten masses. This test, which is used by many manufacturers and users of case-hardened steels, is known in the steel business as the “Brugger test”.
C	Description
Calibration	Adjustment of all measuring equipment to meet the requirements of International Standards. It is usually carried out by a recognised traceable authority and results in the issue of a calibration certificate. Calibration is not the same as Verification
Capstan grips	The gripping of the specimen is largely generated by friction. These grips are mainly used for ropes, textiles etc.
Circumference	The line that goes round or encompasses a circular object
Clip-on extensometer	A clip-on Extensometer is a contact extension measurement device that determines extension between two points. These are reducing in popularity as digital extensometers with higher accuracy, and better features are available, especially for automated testing
Co-efficient Variation	For a set of data, the coefficient of variation is: 100 × standard deviation / mean
Com Port	Communication interface connection usually a serial port on a PC often referred to as COM1, COM 2 etc. Zwick uses this port to connect to the testing machine controller or Auxiliary Devices. See also USB.
Compression	A force tending to compress or reduce something.
Compression platen	There are fixed and moveable compression platens. Compression platens are used for compression tests instead of the specimen grips. Take care to use a safety mandrel for safety when using compression platens to test springs.
Compression Testing	Method for determining behavior of samples under a crushing or compressive force.
Conditioning cycle	The load is applied to, or removed from the specimen in conditioning cycles prior to the main test cycle. A test cycle is normally carried out after the conditioning cycles. Conditioning cycles are often called scrag, or scragging cycles in certain industries.
Correction Curve	Some advanced materials testing machines can compensate for the mechanical losses during compression, or bend / flexural tests (load cell deflection, grips etc.). Zwick testXpert does this. When comparing results between different machines take care to check if the machine is able to correct for machine losses.
Creep	Deformation that occurs over time when a material is subjected to constant stress at a constant temperature
Crosshead	The main beam across the testing machine. This beam moves either up or down at variable speeds producing a tensile or compressive force on the sample under test
D	Description
Deflection	The movement of a structure or structural part as a result of stress.
Diameter	The length of a straight line passing through the centre of a circle and connecting two points on the circumference of the sample
Distance	The property created by the space between two objects or points
Ductility	Ductile fracture is characterised by plastic deformation which precedes failure of the part. Ductility is the ability of a material to accept large amounts of deformation (usually tensile) without fracture. It is the opposite of brittleness
E	Description
Elastic Limit	The limit of distortion, by bending, stretching, etc., that a body can undergo and yet return to its original form when relieved from stress
Elasticity	The ability of a strained material to recover its original size and shape immediately after removal of the stress that caused the deformation
Elongation	The deformation in the direction of load caused by a tensile force.
Energy	A measurement of the work done on a specimen during a test. The energy expended between any two points in a test is measured as the area under the stress/strain curve
Extension	The location of the crosshead / extensometer relative to the original gauge length. Some Standards vary on the interpretation of Extension at different regions of the test.
Extensometer	An instrument or device used to measure deformation in a test specimen of a material. Zwick mainly uses digital extensometers because of the increased measurement accuracy, however there are still some analogue clip-on units within the industry. Read more about how to choose the right extensometer.
F	Description
Force	The capacity to cause physical change to a sample under test
G	Description
Gauge Length	Gauge length is the original length of the sample or extensometer. This value is used to calculate extension. It is often defined in the testing standard. The gauge length is also sometimes taken as the distance between the specimen grips
Grips	A mechanical device that grasps and holds the test specimen
I	Description
Imperial	The standards legalised by the British Parliament.
Initial Peak Force	The initial peak force is the first point at which distance / extension increases and force decreases.
Inner Diameter	The length of a straight line passing through the centre of a circle and connecting two points on the inner circumference of sample.
J	Description
Jog	A button on the control panel that Moves the crosshead up or down manually. Used to manually position the crosshead prior to testing as a quick method to grip or position a test specimen. Zwick systems normally record the crosshead position automatically, and can set the crosshead to any desired position for different specimen. However, for manual positioning a separate control is also possible for the operator.
L	Description
Linear Densitgy	Linear density is a measure of mass per unit length
Load Cell	A transducer which converts a value of force into an electrical signal. All load cells have a lower limit specified in the testing machine calibration accuracy standards for testing machines. Be careful not to externally quote or guarantee test results below the limit stated on your current calibration certificate.
Load reduction curve	This is part of a specimen grip: It allows stress reduction along the grip surface when holding tapes, small hard wires, or similar to reduce breaks in the jaws.
LOP	Limit of Proportionality is the force at the point on a stress/strain curve where the strain is no longer proportional to the stress.
M	Description
Major Span	Distance between lower supports on 4 point bend
Maximum Force	The point of highest force. Also written as ‘Fm’, ‘Fmax’, ‘Rm’, ‘Max.Force’
Mean	A way of finding the 'middle' of a set of data. The ordinary or 'arithmetic' means found by adding up all the values and dividing the total by the number of values
Mean Force	The sum of all force data divided by the number of data points.
Median	The median of a set of data is one way of finding the 'middle' of the data. To find the median, put all the data in a list in order of size, and pick the piece of data which is half way through the list. If there is an even number of values, the median is half way between the middle pair of values
Metric	Of or pertaining to the metre as a standard of measurement of or pertaining to the decimal system of measurement of which a metre is the unit as, the metric system., a metric measurement
Minor Span	Distance between upper loading points on 4 point bend
N	Description
Nadcap	Nadcap is a global accreditation system. For testing machines one important criterion is alignment. This is typically verified according to ASTM E1012-05. See also Alignment.
O	Description
Outer Diameter	The length of a straight line passing through the centre of a circle and connecting two points on the outer circumference of sample
P	Description
Peak	Highest point or maximum value
Peak Force	The point of maximum force (Fm). Some Standards specifically define the correct algorithms for calculating this value.
Preload	Preload is a user defined force that is applied to the specimen before any measurements begin. Also known as Pretension. At this point automatic extensometers can be applied to the test sample to measure elongation, and the test recommenced.
Pretension	Pretension is used in tensile tests and is a user defined force that is applied to the specimen before any measurements begin. Also known as preload
Proof stress ratio	The proof stress ratio (PSR) is calculated from the proof stress at x and the maximum stress: PSR = (Rpx / Rm) * 100. Rpx: Force at elongation value x in N/mm2 (typical 0.2%) Rm: Maximum force in N/mm2
Pull Test	If two components are fixed together then a pull test can be used to measure the force required to seperate them, e.g. pulling a wood screw from a piece of wood. This test is more universally known as a Tensile Test. See also Push Test
Push Test	Used to describe a mechanical test whereby one material is "pushed" against, over, into, or through, another. Another example is a "push out" test (e.g. on electrical connectors) where one component is seperated from another. See also Pull Test
R	Description
Reel Circumference	The line that goes round or encompasses a reel
Resolution	The resolution corresponds to the smallest two digits / values which can be read from a measurement device. Resolution is NOT the same as Accuracy.
S	Description
Sample Break	The point at with the sample breaks or fractures. Also see Specimen.
Sample Break Detection	The Sample Break Detection function measures the rate of decrease in force during a test and when triggered will stop the crosshead. Zwick testXpert software has elaborate algorithms which are perfectly suited to different modes of failure of test samples, without the need for operator involvement.
Sample Height	Sample Height is the original height of the sample of which deflection calculations are made. This is calculated automatically by TestXpert, and can be used to control machine functions based on the measured height of the sample during the test.
SI	Système International (d'Unités) (International System of Units)
Sled Weight	Mass of the sled. This is mainly used for friction tests.
Span	The extent or measure of space between two points or extremities
Specimen	A specimen to be tested is normally prepared from a sample of material. Accorinding to the test mode, Standard, or testing specification it may have to be a produced in a defined geometric shape.
Stage	An event or phase at the beginning, during, or end of the test. TestXpert software has many events which occur during the test. Calculations can be made at the beginning, end or during these events.
Standard Deviation	The standard deviation is also called the root mean square deviation, because it can be found by computing the deviation of each piece of data from the mean, squaring each of these deviations, finding the mean of them and then taking the square root of the mean
Strain	To change (the relations between the parts of a structure or shape) by applying an external force
Stress	An applied force divided by original cross sectional area of the specimen.
T	Description
Tensile Strength	Ultimate strength of a material subjected to tensile loading. It is the maximum stress developed in a material during a tensile test. Click for examples of products used to measure tensile strength.
Tension	A force tending to stretch or elongate a sample or material
TENSTAND	The EU project (TENsile STANDard) has prepared computer-based files, representing typical tensile characteristics of a range of industrially important metallic materials. Read more about TENSTAND.
Test Definition	Outlines the test methods including calculations, variables etc. TestXpert can make tests to most International Standards, and the operator has the chance to make changes and then store them with a new name. The number of test types is only limited by the space on the hard disk of the computer.
Test Height	The distance from the base of the sample to the top of the sample
Test Type	Examples of test types include Tension, Compression, Burst, Peel, 3 Point Flexural, Paper, Seam, Yarn Tear and Friction
Thickness	The dimension between two surfaces of an object, usually the dimension of smallest measure
Thickness Gauge	An instrument for measuring the specimen thickness. This value can be automatically entered into the testing software with the appropriate interface (usually RS232)
Transverse Strain Extensometer	Very high accuracy measuring unit to measure the reduction in width of the specimen in real time during the test. This is used for r value determination on metals, and also for the determination of Poisson ratio. The device is sometimes known as a reduction in width monitor.
U	Description
USB	Universal Serial Bus. An interface available on modern PCs. It is one means of connecting the PC to the testing machine, RS232 is the other. This avoids the need to add special interface cards into the PC, and allows the system to run on a laptop. See also Com port.
V	Description
Verification	The act of comparing the accuracy of the sensors (Load cell, Extensometer, etc.) against a certified standard. Verification is not calibration (the act of adjusting the machine components accuracy to achieve the requirements of the standard.). A verification can result in a ‘fail’ certificate, and extra costs for the customer.
Vertical anisotropy	The vertical anisotropy (r-value) denotes the resistance of sheet metal to reduction in thickness of the metal during uni-axial tensile loading. r = logarithmic width deformation / logarithmic thickness deformation. It enables the deep drawing behaviour of sheet metals to be quantified.
Y	Description
Yield Point	The point at which the strain increases without the associated increase in stress. Only a few materials (eg steel, some plastics) have a yield point and generally only under tensile forces
Yield stress ratio	The yield stress ratio (YSR) is calculated from the upper yield stress and the maximum stress: YSR = (ReH / Rm) * 100 ReH: Upper yield stress in N/mm2 Rm: Maximum stress in N/mm2