The concrete hammer test is useful for determining a variety of concrete characteristics in anon-destructive way. With it, a technician can assess the uniformity and quality of the concretebased on standard specifications, compare the quality of concrete elements and establish arelative strength profile for a concrete structure. Each of these results can be determinedusing the same simple tool: a concrete test hammer. Skyrim increase weight limit command.
How to Perform the Concrete Hammer TestPerforming a concrete hammer test is relatively simple. You simply hold the concrete test hammer (AKA,impact hammer or rebound hammer) of your choice against the concrete structure and release thespring-loadedhammer. Generally, the hammer tool will have a digital window and scale along the side where you canviewthe rebound value from the hammer's impact. Steps for Performing the Concrete Hammer Test. Use a to check the calibration of your test hammer after every1,000-2,000 impacts. You should also test your hammer prior to each use.
Stainless Steel Electronic Testing Equipment 0.7 J Single Energy Spring Impact Test Hammer Introductions This spring impact hammer is mainly used to test household and similar electrical appliances shell, lever, handle, knobs, lights and other shell to withstand mechanical shocks. The table compares compressive strength and impact energy between Original Schmidt Hammer, Silver Schmidt, Schmidt Live, and Rock Rebound Test Hammers. Most versions are divided into two concrete rebound hammer types based on the impact energy they produce. Schmidt Concrete Test Hammers are available in Type N or Type B model.
Make sure the concrete surface you will be testing is smooth, clean and dry. If the surface is not smooth, use a to prepare it for the hammer test. Your chosen impact point should be at least 20mm away from the edge of the structure or anyshape discontinuities. Take six rebound readings at each site and determine the average for a reliable value.It's also important to keep in mind that the types of aggregate and cement used to createconcretecan influence the results of a concrete hammer test. Therefore, you will need to evaluate theresults of the test based on the specifications of the mixture.
Age, curing and carbonation ofconcrete can also affect the rebound number determined by your test hammer. Cons. The results are based on a local point and aren't a complete indicator of concrete'scompressive strength. Other flaws in the concrete's structure cannot be detected using only this test. The areas you test must be carefully selected and prepared.When used within its capabilities, the concrete hammer test is easy to perform, reliable andapplicable to any structure, since it isn't destructive. When used within its capabilities, the concrete hammer test is easy to perform, reliable and applicableto any structure, since it isn't destructive.A calibration anvil and a grinding stone are important to have on hand when preparing to perform theconcrete hammer test.
But, when it comes to the test itself, all you need is the hammer! There are a fewmain types of tochoose from.Concrete test hammers are sometimes called Swiss Hammers or SchmidtHammers, and this is where the name comes from. Schmidt Hammers can be used for a wide varietyof non-destructive concrete tests. The Type N is ideal for concrete strengths ranging from1,400-10,000psi. Schmidt The NR Hammer is also ideal for concrete strengths ranging from1,400-10,000psi. However, the NR has the added capability of automatically recording reboundnumbers as a bar chart on a paper strip for quick and easy comparison. Each strip chart can logup to 4,000 impacts.
The Gilson Type N can test concrete strength within the same range as theSchmidt Type N. This test hammer can also be used to estimate how much damage a concretestructure has taken due to freezing or fire.
It also comes at a slightly lower price point.
Modal testing is the form of vibration testing of an object whereby the natural (modal) frequencies, modal masses, modal damping ratios and mode shapes of the object under test are determined.
A modal test consists of an acquisition phase and an analysis phase. The complete process is often referred to as a Modal Analysis or Experimental Modal Analysis.
There are several ways to do modal testing but impact hammer testing and shaker (vibration tester) testing are commonplace. In both cases energy is supplied to the system with a known frequency content. Where structural resonances occur there will be an amplification of the response, clearly seen in the response spectra. Using the response spectra and force spectra, a transfer function can be obtained. The transfer function (or frequency response function (FRF)) is often curve fitted to estimate the modal parameters; however, there are many methods of modal parameter estimation and it is the topic of much research.
Impact Hammer Modal Testing[edit]
An ideal impact to a structure is a perfect impulse, which has an infinitely small duration, causing a constant amplitude in the frequency domain; this would result in all modes of vibration being excited with equal energy. The impact hammer test is designed to replicate this; however, in reality a hammer strike cannot last for an infinitely small duration, but has a known contact time. The duration of the contact time directly influences the frequency content of the force, with a larger contact time causing a smaller range of bandwidth. A load cell is attached to the end of the hammer to record the force. Impact hammer testing is ideal for small light weight structures; however as the size of the structure increases issues can occur due to a poor signal to noise ratio. This is common on large civil engineering structures.
Shaker Modal Testing[edit]
A shaker is a device that excites the object or structure according to its amplified input signal. Several input signals are available for modal testing, but the sine sweep and random frequency vibration profiles are by far the most commonly used signals.
Small objects or structures can be attached directly to the shaker table. With some types of shakers, an armature is often attached to the body to be tested by way of piano wire (pulling force) or stinger (Pushing force). When the signal is transmitted through the piano wire or the stinger, the object responds the same way as impact testing, by attenuating some and amplifying certain frequencies. These frequencies are measured as modal frequencies. Usually a load cell is placed between the shaker and the structure to obtain the excitation force.
For large civil engineering structures much larger shakers are used, which can weigh 100kg and above and apply a force of many hundreds of newtons. Several types of shakers are common: rotating mass shakers, electro-dynamic shakers, and electrohydraulic shakers. For rotating mass shakers the force can be calculated from knowing the mass and the speed of rotation; for the electro-dynamic shaker the force can be obtained through a load cell, or an accelerometer placed on the moving mass of the shaker. Shakers can have an advantage over the impact hammer as they can supply more energy to a structure over a longer period of time. However, problems can also be introduced; shakers can influence the dynamic properties of the structure and can also increase the complexity of analysis due to windowing errors.
See also[edit]
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The concrete hammer test is useful for determining a variety of concrete characteristics in anon-destructive way. With it, a technician can assess the uniformity and quality of the concretebased on standard specifications, compare the quality of concrete elements and establish arelative strength profile for a concrete structure. Each of these results can be determinedusing the same simple tool: a concrete test hammer. Skyrim increase weight limit command.
How to Perform the Concrete Hammer TestPerforming a concrete hammer test is relatively simple. You simply hold the concrete test hammer (AKA,impact hammer or rebound hammer) of your choice against the concrete structure and release thespring-loadedhammer. Generally, the hammer tool will have a digital window and scale along the side where you canviewthe rebound value from the hammer's impact. Steps for Performing the Concrete Hammer Test. Use a to check the calibration of your test hammer after every1,000-2,000 impacts. You should also test your hammer prior to each use.
Stainless Steel Electronic Testing Equipment 0.7 J Single Energy Spring Impact Test Hammer Introductions This spring impact hammer is mainly used to test household and similar electrical appliances shell, lever, handle, knobs, lights and other shell to withstand mechanical shocks. The table compares compressive strength and impact energy between Original Schmidt Hammer, Silver Schmidt, Schmidt Live, and Rock Rebound Test Hammers. Most versions are divided into two concrete rebound hammer types based on the impact energy they produce. Schmidt Concrete Test Hammers are available in Type N or Type B model.
Make sure the concrete surface you will be testing is smooth, clean and dry. If the surface is not smooth, use a to prepare it for the hammer test. Your chosen impact point should be at least 20mm away from the edge of the structure or anyshape discontinuities. Take six rebound readings at each site and determine the average for a reliable value.It's also important to keep in mind that the types of aggregate and cement used to createconcretecan influence the results of a concrete hammer test. Therefore, you will need to evaluate theresults of the test based on the specifications of the mixture.
Age, curing and carbonation ofconcrete can also affect the rebound number determined by your test hammer. Cons. The results are based on a local point and aren't a complete indicator of concrete'scompressive strength. Other flaws in the concrete's structure cannot be detected using only this test. The areas you test must be carefully selected and prepared.When used within its capabilities, the concrete hammer test is easy to perform, reliable andapplicable to any structure, since it isn't destructive. When used within its capabilities, the concrete hammer test is easy to perform, reliable and applicableto any structure, since it isn't destructive.A calibration anvil and a grinding stone are important to have on hand when preparing to perform theconcrete hammer test.
But, when it comes to the test itself, all you need is the hammer! There are a fewmain types of tochoose from.Concrete test hammers are sometimes called Swiss Hammers or SchmidtHammers, and this is where the name comes from. Schmidt Hammers can be used for a wide varietyof non-destructive concrete tests. The Type N is ideal for concrete strengths ranging from1,400-10,000psi. Schmidt The NR Hammer is also ideal for concrete strengths ranging from1,400-10,000psi. However, the NR has the added capability of automatically recording reboundnumbers as a bar chart on a paper strip for quick and easy comparison. Each strip chart can logup to 4,000 impacts.
The Gilson Type N can test concrete strength within the same range as theSchmidt Type N. This test hammer can also be used to estimate how much damage a concretestructure has taken due to freezing or fire.
It also comes at a slightly lower price point.
Modal testing is the form of vibration testing of an object whereby the natural (modal) frequencies, modal masses, modal damping ratios and mode shapes of the object under test are determined.
A modal test consists of an acquisition phase and an analysis phase. The complete process is often referred to as a Modal Analysis or Experimental Modal Analysis.
There are several ways to do modal testing but impact hammer testing and shaker (vibration tester) testing are commonplace. In both cases energy is supplied to the system with a known frequency content. Where structural resonances occur there will be an amplification of the response, clearly seen in the response spectra. Using the response spectra and force spectra, a transfer function can be obtained. The transfer function (or frequency response function (FRF)) is often curve fitted to estimate the modal parameters; however, there are many methods of modal parameter estimation and it is the topic of much research.
Impact Hammer Modal Testing[edit]
An ideal impact to a structure is a perfect impulse, which has an infinitely small duration, causing a constant amplitude in the frequency domain; this would result in all modes of vibration being excited with equal energy. The impact hammer test is designed to replicate this; however, in reality a hammer strike cannot last for an infinitely small duration, but has a known contact time. The duration of the contact time directly influences the frequency content of the force, with a larger contact time causing a smaller range of bandwidth. A load cell is attached to the end of the hammer to record the force. Impact hammer testing is ideal for small light weight structures; however as the size of the structure increases issues can occur due to a poor signal to noise ratio. This is common on large civil engineering structures.
Shaker Modal Testing[edit]
A shaker is a device that excites the object or structure according to its amplified input signal. Several input signals are available for modal testing, but the sine sweep and random frequency vibration profiles are by far the most commonly used signals.
Small objects or structures can be attached directly to the shaker table. With some types of shakers, an armature is often attached to the body to be tested by way of piano wire (pulling force) or stinger (Pushing force). When the signal is transmitted through the piano wire or the stinger, the object responds the same way as impact testing, by attenuating some and amplifying certain frequencies. These frequencies are measured as modal frequencies. Usually a load cell is placed between the shaker and the structure to obtain the excitation force.
For large civil engineering structures much larger shakers are used, which can weigh 100kg and above and apply a force of many hundreds of newtons. Several types of shakers are common: rotating mass shakers, electro-dynamic shakers, and electrohydraulic shakers. For rotating mass shakers the force can be calculated from knowing the mass and the speed of rotation; for the electro-dynamic shaker the force can be obtained through a load cell, or an accelerometer placed on the moving mass of the shaker. Shakers can have an advantage over the impact hammer as they can supply more energy to a structure over a longer period of time. However, problems can also be introduced; shakers can influence the dynamic properties of the structure and can also increase the complexity of analysis due to windowing errors.
See also[edit]