Notch impact test deice is in our day widely used and very common and such tests are conducted in accordance with current requirements. Notch impact tests have a long history.

In 1869 S. B. Russell introduced the idea of break energy, which was a first step into an era of machinery industry. The pendulum break test so developed was a result of Russell’s first tentative tests. This first test was measured by means of flour-notched scales. In 1897 Frémont used a spring machine to show how correct had been the first step and worked to measure the same phenomenon which led to his introducing a new test. Particularly in 1901 Georges Charpy re-designed the pendulum to improve Russell’s standard method to give notched and generally precise technical features. We have had to limit ourselves here to an only brief account of this history because it is a long story indeed.

Devotrans manufactures its notch impact test devices with the following codes: DVT CD D 50IC, ZGT 7052 H30.

Find below information about the significance of the Notch Impact Experiment.

What is the purpose of the notch impact experiment?

The main purpose of the notch impact experiment is to artificially create a strain concentration that may eventually be present in the material (tension build-up) at the base of a notch during the impact to determine the strength that the material will develop against dynamic challenges. For instance, there is no need to open notches in grey cast iron samples since the tiny graphite plates in the material will play the role of notches.

When a notched sample is challenged, a perpendicular strain is applied to the base of the notch. The starting of the break is a result of the effect of this strain. For the sample to break, this perpendicular (normal) strain must be larger than the cohesive resistance that keep the crystals together or prevents them from shifting. If this happens before the plastic sample is able to change shape, this phenomenon is called crispy break to use a daily language idiom. The broken surface is a flat separation surface.

During the Notch Impact Test, the plastic change of shape occurs usually before the sample breaks. Under the effect of the force applied, in addition to the normal (perpendicular) strain, a shifting strain with a 45° angle to this emerges. When the shifting strain exceeds the shifting resistance (critical shifting strain) the property of elasticity stops and the plastic starts to change shape. In this situation, first the plastic change of shape occurs and then the break. This is called ductile break and the break surface presents a rugged surface.

There are in general two types of notch impact tests

- Charpy impact test

- İzod impact test

In the impact test, the energy required for the sample to break under a dynamic challenge must be correctly calculated. The value found as a result of the calculation of such required energy is defined as the impact strength of the material. In these experiments, a schematically shown pendulum-type device is used to obtain the results. The pendulum with a weight G is raised to a height h where its potential energy is (G x h). When the pendulum is let drop from this height, it moves on a vertical plane to break the sample and goes up in the other direction up to a height of h 1. Thus, the potential energy that remains in the pendulum after the break is (G x h1).

The difference between the potential energy at the moment when the pendulum contacts the sample and the potential energy that remains in the pendulum after the sample has broken gives the energy required for the sample to break, in other words, the impact strength. This energy can be shown using the formula below:

Break energy = G (h - h 1 ) = G.L. (cosβ - cosα )

G = weight of pendulum (kg)

L = distance from the gravity centre of the pendulum to the oscillation centre of the pendulum (m),

h = drop height of the gravity centre of the pendulum (m),

hı= elevation height of the gravity centre of the pendulum (m),

α = drop angle (degrees),

β = elevation angle (degrees),

The impact resistance is expressed in kg-m or kg-m/cm 2.

As this experiment is entirely empirical and the material may present different properties as conditions change, to obtain accurate results it is important to correctly place the samples in the device.

During the experiment, the pendulum is first raised to a height where it can have the preset potential energy. Then the sample is appropriately placed. For instance, in the Charpy test, which is the most common, the sample is placed in such a manner that it entirely leans against the fulcrums and the oscillation plane of the hammer and the symmetry plane of the sample overlaps within 0.5 mm. This can be obtained by means of an aid attached to the device. Once the sample has been properly placed, the display is reset and the pendulum is allowed to fall freely in a regular manner. The result is read on the display after the experiment.

Correctly conducting these experiments is of vital importance for the production. But this is not enough. The manufacturers of notch impact test devices are also important.

If the manufacturer does not possess the required competence from the production of the device to the technical information about operating it, the test can become even harmful. For instance, in addition to the sale services provided by the manufacturer, technical service is also important and the calibration results must also comply with the standards to make sure that the device measures correctly. This is why, as in all quality control devices, you must consider all aspects of the matter before buying a Notch Impact Device.
For more information about the notch impact device or the notch impact experiment, find below the most useful search words.

Notch impact device, notch impact experiment, notch impact test sample, notch impact experiment results, notch impact test device, notch impact experiment theoretical information, notch impact strength, factors that have an effect on notch impact strength, notch impact saturation, notch impact experiment pdf, notch impact experiment, what is a notch impact experiment, purpose of notch impact experiment, notch impact experiment results, download notch impact experiment, notch impact experiment report

Note: The products or links mentioned in the article may not be updated. For up-to-date information please contact us.