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Three-point Flexural Test
The three-point bending flexural test provides values for the modulus of elasticity in bending E_f, flexural stress \sigma_f, flexural strain \epsilon_f and the flexural stress–strain response of the material. This test is performed on a universal testing machine (tensile testing machine or tensile tester) with a three-point or four-point bend fixture. The main advantage of a three-point flexural test is the ease of the specimen preparation and testing. However, this method has also some disadvantages: the results of the testing method are sensitive to specimen and loading geometry and strain rate. Testing method The test method for conducting the test usually involves a specified test fixture on a universal testing machine. Details of the test preparation, conditioning, and conduct affect the test results. The sample is placed on two supporting pins a set distance apart. Calculation of the flexural stress \sigma_f :\sigma_f = \frac for a rectangular cross section :\si ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Three Point Flexural Test
The three-point bending flexural test provides values for the modulus of elasticity in bending E_f, flexural stress \sigma_f, flexural strain \epsilon_f and the flexural stress–strain response of the material. This test is performed on a universal testing machine (tensile testing machine or tensile tester) with a three-point or four-point bend fixture. The main advantage of a three-point flexural test is the ease of the specimen preparation and testing. However, this method has also some disadvantages: the results of the testing method are sensitive to specimen and loading geometry and strain rate. Testing method The test method for conducting the test usually involves a specified test fixture on a universal testing machine. Details of the test preparation, conditioning, and conduct affect the test results. The sample is placed on two supporting pins a set distance apart. Calculation of the flexural stress \sigma_f :\sigma_f = \frac for a rectangular cross section :\si ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Flexural Modulus
In mechanics, the flexural modulus or bending modulus is an intensive property that is computed as the ratio of stress to strain in flexural deformation, or the tendency for a material to resist bending. It is determined from the slope of a stress-strain curve produced by a flexural test (such as the ASTM D790), and uses units of force per area. The flexural modulus defined using the 2-point (cantilever) and 3-point bend tests assumes a linear stress strain response. For a 3-point test of a rectangular beam behaving as an isotropic linear material, where ''w'' and ''h'' are the width and height of the beam, ''I'' is the second moment of area of the beam's cross-section, ''L'' is the distance between the two outer supports, and ''d'' is the deflection due to the load ''F'' applied at the middle of the beam, the flexural modulus: : E_ = \frac From elastic beam theory :d = \frac and for rectangular beam : I = \fracwh^3 thus E_ = E (Elastic modulus) For very small strains ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Flexural Stress
Flexural strength, also known as modulus of rupture, or bend strength, or transverse rupture strength is a material property, defined as the stress in a material just before it yields in a flexure test. The transverse bending test is most frequently employed, in which a specimen having either a circular or rectangular cross-section is bent until fracture or yielding using a three-point flexural test technique. The flexural strength represents the highest stress experienced within the material at its moment of yield. It is measured in terms of stress, here given the symbol \sigma. Introduction When an object is formed of a single material, like a wooden beam or a steel rod, is bent (Fig. 1), it experiences a range of stresses across its depth (Fig. 2). At the edge of the object on the inside of the bend (concave face) the stress will be at its maximum compressive stress value. At the outside of the bend (convex face) the stress will be at its maximum tensile value. These in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Test Method
A test method is a method for a test in science or engineering, such as a physical test, chemical test, or statistical test. It is a definitive procedure that produces a test result. In order to ensure accurate and relevant test results, a test method should be "explicit, unambiguous, and experimentally feasible.", as well as effective and reproducible. A test can be considered an observation or experiment that determines one or more characteristics of a given sample, product, process, or service. The purpose of testing involves a prior determination of expected observation and a comparison of that expectation to what one actually observes. The results of testing can be qualitative (yes/no), quantitative (a measured value), or categorical and can be derived from personal observation or the output of a precision measuring instrument. Usually the test result is the dependent variable, the measured response based on the particular conditions of the test or the level of the independ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Test Fixture
A test fixture is an environment used to consistently test some item, device, or piece of software. Test fixtures can be found when testing electronics, software and physical devices. Electronics In testing electronic equipment such as circuit boards, electronic components, and chips, a test fixture is a device or setup designed to hold the device under test in place and allow it to be tested by being subjected to controlled electronic test signals. Examples are a bed of nails tester or SmartFixture. Electronics Test Fixture.jpg, Side connectors, centering pins, test needles, pre-centering parts. Functional Test Fixture for electroncis.jpg, A functional test fixture is a complex device to interface the device under test (DUT) to the automatic test equipment (ATE). Software A software test fixture sets up a system for the software testing process by initializing it, thereby satisfying any preconditions the system may have. For example, the Ruby on Rails web framework uses ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Universal Testing Machine
A universal testing machine (UTM), also known as a universal tester, materials testing machine or materials test frame, is used to test the tensile strength and compressive strength of materials. An earlier name for a tensile testing machine is a tensometer. The "universal" part of the name reflects that it can perform many standard tensile and compression tests on materials, components, and structures (in other words, that it is versatile). Components Several variations are in use. Common components include: * Load frame - Usually consisting of two strong supports for the machine. Some small machines have a single support. * Load cell - A force transducer or other means of measuring the load is required. Periodic calibration is usually required by governing regulations or quality system. * Cross head - A movable cross head (crosshead) is controlled to move up or down. Usually this is at a constant speed: sometimes called a ''constant rate of extension'' (CRE) machine. So ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Flexural Modulus
In mechanics, the flexural modulus or bending modulus is an intensive property that is computed as the ratio of stress to strain in flexural deformation, or the tendency for a material to resist bending. It is determined from the slope of a stress-strain curve produced by a flexural test (such as the ASTM D790), and uses units of force per area. The flexural modulus defined using the 2-point (cantilever) and 3-point bend tests assumes a linear stress strain response. For a 3-point test of a rectangular beam behaving as an isotropic linear material, where ''w'' and ''h'' are the width and height of the beam, ''I'' is the second moment of area of the beam's cross-section, ''L'' is the distance between the two outer supports, and ''d'' is the deflection due to the load ''F'' applied at the middle of the beam, the flexural modulus: : E_ = \frac From elastic beam theory :d = \frac and for rectangular beam : I = \fracwh^3 thus E_ = E (Elastic modulus) For very small strains ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Newton (unit)
The newton (symbol: N) is the unit of force in the International System of Units (SI). It is defined as 1 kg⋅m/s, the force which gives a mass of 1 kilogram an acceleration of 1 metre per second per second. It is named after Isaac Newton in recognition of his work on classical mechanics, specifically Newton's second law of motion. Definition A newton is defined as 1 kg⋅m/s (it is a derived unit which is defined in terms of the SI base units). One newton is therefore the force needed to accelerate one kilogram of mass at the rate of one metre per second squared in the direction of the applied force. The units "metre per second squared" can be understood as measuring a rate of change in velocity per unit of time, i.e. an increase in velocity by 1 metre per second every second. In 1946, Conférence Générale des Poids et Mesures (CGPM) Resolution 2 standardized the unit of force in the MKS system of units to be the amount needed to accelerate 1 kilogram of mass at the rate ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fracture Toughness
In materials science, fracture toughness is the critical stress intensity factor of a sharp crack where propagation of the crack suddenly becomes rapid and unlimited. A component's thickness affects the constraint conditions at the tip of a crack with thin components having plane stress conditions and thick components having plane strain conditions. Plane strain conditions give the lowest fracture toughness value which is a material property. The critical value of stress intensity factor in mode I loading measured under plane strain conditions is known as the plane strain fracture toughness, denoted K_\text. When a test fails to meet the thickness and other test requirements that are in place to ensure plane strain conditions, the fracture toughness value produced is given the designation K_\text. Fracture toughness is a quantitative way of expressing a material's resistance to crack propagation and standard values for a given material are generally available. Slow self-sust ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stress Intensity Factor
In fracture mechanics, the stress intensity factor () is used to predict the stress state ("stress intensity") near the tip of a crack or notch caused by a remote load or residual stresses. It is a theoretical construct usually applied to a homogeneous, linear elastic material and is useful for providing a failure criterion for brittle materials, and is a critical technique in the discipline of damage tolerance. The concept can also be applied to materials that exhibit ''small-scale yielding'' at a crack tip. The magnitude of depends on specimen geometry, the size and location of the crack or notch, and the magnitude and the distribution of loads on the material. It can be written as: :K = \sigma \sqrt \, f(a/W) where f(a/W) is a specimen geometry dependent function of the crack length, , and the specimen width, , and is the applied stress. Linear elastic theory predicts that the stress distribution (\sigma_) near the crack tip, in polar coordinates (r,\theta) with or ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
