Tensile testing represents the most common type of test for materials and products. Characterizing and reporting tensile test properties is a basic need in most labs from quality control to R & D. Many tensile tests are performed on static systems, although in many cases dynamic systems can be used for tensile tests. System considerations are test speed, control mode, ultimate load, and test displacement.
A material or product is squeezed or compressed by aligned opposing loads or forces. Compression testing can be performed on materials for a variety of purposes. Depending on the material type, compressive properties can be dramatically different than tensile properties. Compression tests can be performed on static or dynamic systems. Static systems are usually the system of choice due to the larger displacement offered, and the relatively slow speed of the system for safety purposes. The most common fixture for compression testing is the compression platen. Ideally, a set of compression platens will provide parallel surfaces for loading of the specimen. They also should be of sufficient hardness and smoothness as not to influence the specimen results. Platens are available in two types, fixed and spherical seats. The spherical units provide for automatic alignment for higher modules materials, or specimens that have loading surfaces that are not parallel.
Adhesion, bond or peel tests are used to evaluate joints, adhesives, coatings or adhesive tapes adherence, bond strength or peel strength. ASTM D-952 defines bond strength as the tensile stress required to rupture a bond formed by an adhesive between two metal blocks. Adhesion as the state in which two surfaces are held together by interfacial forces, which may consist of valence forces, interlocking action, or both. Adhesion is one of the most important properties of a coating (thin film, paint, plating or other systems). ASTM C-313 standards provide a method to measure of the adherence of porcelain enamel and ceramic coatings to sheet metal. According to ASTM D-903, the peel or stripping strength of an adhesive bond is the average load per unit width of bond line required to part bonded materials where the angle of separation is 180 degrees and separation rate is 6 in/min. ASTM D-1781 uses the applied torque required to separate an adhesive and adherend in the climbing drum peel test to provide measure of adhesion or peel resistance. Peel strength is commonly used to characterize adhesive tapes and coatings.
Ductility is the ability to undergo plastic deformation in tension or bending before fracturing. The ductility of metals or ductile plastic materials are typically evaluated in tensile tests. The degree of permanent plastic deformation or strain in terms of % elongation or % reduction in area provides a measure of ductility.
Specialized bend tests are also used to evaluate the ductility of welds according to ASTM E-190. The ductility of welded joints is often evaluated in bend tests.
Tests that characterize material performance under constant strain or stress conditions usually at elevated temperatures fall into the category of creep, stress relaxation or stress rupture. These tests can provide important information as to material or component properties under longer term conditions. Creep or stress rupture test are important in evaluating high temperature aerospace or jet engine component materials. Stress relaxation tests are usually performed under constant strain conditions. This usually involves going to a specific load or strain point then holding the strain value. The resulting decrease in load or stress values is recorded over time. Creep tests are usually performed under constant load or stress conditions. These types of tests are performed by going to a load or stress point, then holding the load or stress value. The resulting increase in strain is recorded over time. Short and medium term creep and stress relaxation testing can be performed on static or dynamic systems. However, some long term creep tests utilize a special test frame designed specifically for that purpose.
Also called shock testing, it is often performed as part of a hardware qualification or design process. Information obtained during shock testing can improve the survivability of products as well as verify that they will perform properly in service. In aerospace applications, these tests are often pyrotechnic separation, or pyroshock, events associated with launch vehicle applications. In many commercial applications, shock or drop testing is related to shipping and handling events to which a product might be exposed. The purpose of shock testing is to determine the mechanical fragility level of a product, that is, the deceleration level where damage is likely to occur. This information is most useful for package design and testing purposes, although it is also very important for product analysis for the in-use environment as well. Shock testing involves shaping or programming the nature of a shock input pulse in order to characterize both the velocity change and the acceleration response of a typical product. This is important because products fail in distinct ways depending primarily on the nature of the shock input. Normally, this involves programming short duration half-sine pulses and longer duration trapezoidal shaped shock pulses into a product.
Impact strength tests are also considered shock tests. Impact strength is determined through Charpy or Izod pendulum impact tests, dead weight drop (Gardener / Gardner) tests and tensile shock load tests.
May also be called dynamic testers. Fatigue Testers measure the fatigue resistance, or resistance to failure, of materials under controlled conditions of cyclic deformation. Failure of the test piece is the result of crack growth and the design of the machine. The cyclic load may be applied using a tensile tester with cycling capability, rotating beam tester or vibration tester.
Friction testers determine the coefficient of friction or the friction force, the resisting force tangential to the interface between two bodies when, under the action of an external force, one body moves or tends to move relative to the other. Wear testers evaluate the amount or type of wear (material removal or transfer) that occurs between two surface under wet, dry, lubricated conditions or with abrasive particles. A pin on disc tester is a common machine used for wear tests. An applied load is transmitted through the pin to a rotating disc. The pin and disc are made of or coated with the materials to be evaluated.
Flexure or flex tests are used to evaluate the strength of brittle, fibrous, anisotropic or low ductility materials including ceramics, composites, cast irons, highly loaded plastics, wood, concrete and refractories. Flexure testing consists of applying a load to a beam of the test material or sample, which is supported at both ends. Flexural strength, fiber strength or modulus of rupture (MOR) is reported in these tests. Material properties can vary based upon the direction that stress is applied. For instance, concrete is very strong in compression, but weak in tension. Depending on the material rigidity, stiffness, or specifications either a three-point or four-point configuration is used. Four-point bend tests provide a known, uniform stress between the two central points. Test results are included as long as the sample breaks between the two central points. Specific test standards include ASTM D-790 for plastics, ASTM C-674 for fired whiteware, ASTM D-797 for elastomers, ASTM A-438 for cast iron and ASTM D-86 for glass materials.
The term bend test is sometimes used to describe flexure tests, although bend or bending test types vary greatly and can be much different than a simple beam loading test. Bend test specifications are often particular to specific materials. Specialized bend tests are used to evaluate the ductility of welds according to ASTM E-190. Structural steel products are evaluated by bending a sample to a specified inside diameter (ASTM A-360, steel products).
Hydrostatic or burst testers apply an internal pressure and/or flow using a fluid (gas or liquid) to evaluate fittings, pipe, tubing, vessel, cylinders as well as other hydraulic, pneumatic or process components. The tests may determine what flows or pressure a component can withstand before catastrophic failure occurs or leaks develop.
The two most commonly used methods are Charpy and Izod. Impact tests measure the energy absorbed by the specimen before it breaks, a quantity composed of several energy contributions, including energy absorbed by the impact machine through vibrations after initial contact with the specimen and loss in pendulum energy (in pendulum impact tests) when the hammer strikes the specimen as well as the total energy consumed by specimen deformation and fracture. Although it is very difficult to measure many of the individual energy contributions, impact tests are a valuable comparative test method.
The shear strength is defined as the maximum stress that a material can withstand before failure in shear. In a planar shear test, opposing forces are applied parallel to the cross-sectional area under test.
Torsion tests also provide an indication of shear properties. Torsion test evaluate materials or products under twisting loads or opposing radial forces according to ASTM E-143 or ISO equivalent standards. Data from torsion test is used to construct a stress-strain diagram and to determine elastic limit torsional modulus of elasticity, modulus of rupture in torsion, and torsional strength.
Calculation of shear strength depends upon the test method. For instance, the shear strength of a plastic is the maximum load required to shear a specimen in such a manner that the resulting pieces are completely clear of each other. Plastic shear strength is reported in psi based on the area of the sheared edge (ASTM D-732). Timber shear strength is determined by methods given in ASTM D-143 and ASTM D-198. ASTM E-299 defines the shear strength of a structural adhesive has the maximum shear stress in the adhesive prior to failure under torsional loading.
Texture analysis is primarily concerned with the evaluation of mechanical characteristics where a food is subjected to a controlled force from which a deformation curve of its response is generated. Texture analysis is an integral part of the production chain, generating benefits throughout, from research and development to process optimization and production. Key fundamental characteristics which affect finished product texture quality are identified throughout the initial stages of development after which they may be selected for at-line process control measurements. Common characteristics analyzed include hardness, cohesiveness, elasticity, adhesiveness, and viscosity. Secondary characteristics include brittleness, chewiness and gumminess.
Vibration test systems are used to evaluate materials, products and packages for design purposes as well as to simulate the vibration effects of product transportation. Vibration consists of an oscillating load.
Other specialized, proprietary or unlisted tests or standard methods such as tear tests, breaking or fiber strength, wet strength, spring testers, asphalt testers or other specialty test equipment.
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The maximum linear speed or speed range of the crosshead or other test mechanism during testing. The test speed will change the strain rate during the test. Applies mainly to tensile, compression or universal test machines.
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This is the full required range of test temperature. Ambient operating temperature range is used here, unless the test machine has an integral or optional environmental chamber, heater or chiller device.
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This is the full required range of test humidity. Ambient operating humidity range is used here, unless the test machine has an integral or optional environmental chamber or humidity generator.
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The maximum pressure or pressure range that can be applied during a test. Applies mainly to hydrostatic or burst testers as well as other specialized types of test equipment.
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The machine has an analog display or control panel. Analog display would consist of a meter or simple indicator. Analog control panel consists of analog user inputs such as potentiometers, dials, switches, for adjustment of output, ranges, etc.
The machine uses a digital display or control panel. Digital displays provide a discrete numeric or alphanumeric visual output such as LED or LCD displays. Digital control panels have digital keypads or menus for programming.
Can be controlled or monitored remotely with a computer via interface.
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; Temperature Measuring Range:-30 C to 900 C (-25 F to 1600 F); Temperature Accuracy :0.75 C; Response Time:250ms; Display Technology:LED RoHS Compliant: NA
Mini Infrared Thermometer; Response Time:0.50s; Temperature Accuracy ?:2?F; Temperature Measuring Range:-30?C to 500?C; Accuracy:+/-1%; Battery Size Code:9V RoHS Compliant: NA
Test, Temperature; Temperature Accuracy ?:3?F; Temperature Measurement Functions:Primary display user selectable for IR or Humidity. Secondary display ambient temperature.; Temperature Measuring Range:-4 to 140?F RoHS Compliant: NA
IR Thermometer; Display Technology:LED; Features:1degF/C max resolution, 0.95 fixed emissivity 12:1 distance to target ratio, auto power off, auto data hold, backlit display, built-in laser pointer; No. of Batteries:1 RoHS Compliant: NA
IR Thermometer; Kit Contents:Complete with 9V battery and hard carrying case; No. of Batteries:1; Temperature Accuracy ?:2?F; Temperature Measuring Range:-58 to 1832 F (-50 to 1000 C) RoHS Compliant: NA
IR Thermometer; Certificate of Calibration:Yes With Data; Kit Contents:Complete with 9V battery and hard carrying case; No. of Batteries:1; Temperature Accuracy ?:2?F; Temperature Measuring Range:-58 to 1832 F (-50 to 1000 C) RoHS Compliant: NA
