Pendulum impact device

A simple schematic of a pendulum impact device (PID) is given in Fig. 1. This equipment permits the permanent deformation pressure (H) of a compact of material to be determined [30,31]. Flat-faced tablets of the test substance are compressed at different compression forces and then subjected to impact with a... 

Fig. 1 Schematic diagram of the pendulum impact device (PID) used to determine the indentation hardness of materials. (Adapted from Ref. 30.)...

The Strain Index is determined from data obtained using the pendulum impact device. 

Indentation hardness determinations were performed in dynamic mode ( 1500 mm/sec impact speed) using a pendulum impact device and in quasistatic mode ( 0.008 mm/sec impact speed) with a custom-built indentation tester. The spherical indenters were of 2.54 cm diameter and 65.6 g mass, and the pendulum length was 92.3 cm with a release angle of 30°. Quasistatic indentation forces were selected to produce indentations of a similar size to the dynamic indentation test (1.5 to 2.0 mm radius). The compact indentations were measured using a white light interferometer (Zygo Corporation, Middlefield, Connecticut, U.S.A.) and the dent depth, dent diameter, apparent radius of curvature, and pendulum initial and rebound heights were used to calculate the indentation hardness of the compacts. 

Figure 7-4. Drawing d Izod pendulum impact device. Close-up test sample clamped in holder (Yee 1987 reprinted with permission of John Wiley and Sons and the American Society for Testing Materials. Copyright ASTM International.)...

Figure 8.7 Schematic Illustration of a pendulum type impact testing device...

The Izod and Charpy impact tests are mostly used. A defined pendulum strikes the specimen sample, notched or un-notched, clamped with a defined device. The absorbed energy is calculated and expressed ... 

A pendulum may be used (Charpy, Izod, tensile impact) to determine the work of fracture (Brown, 1999). Instrumented devices provided with piezoelectric transducers are also available load-time or load-displacement curves can be recorded (Merle et al., 1985), giving as much information as static tests. Servohydraulic or pneumatic setups and falling weight devices are also used. The drop ball test from the US Food and Drug Administration, is especially useful for optical lenses (acrylate networks). 

Tensile impact can also be carried out with a pendulum apparatus equipped with a device to hold the test piece so that on impact by the pendulum the test piece is strained in tension. There are two types of test piece holder, one where the test piece is held on the frame of the apparatus and the other where it is held in the head of the pendulum. In both approaches corrections have to be made for the energy used in moving part of the test piece support. 

There are other tests used to evaluate the impact behavior of plastics, including many special setups just for evaluating specific products. These special test setups are usually applicable only to one company or association that has found them to be proven useful. Some of these special tests have then become standards in their own industry, such as ASTM and UL guidelines. Among the more popular ASTM standards are its D 256, D 1709, D 1822, D 2289, D 3029, D 3099, D 3420, and a few others. In these tests including the special ones, a material is impacted by using various devices such as a ball on a pendulum or puncture tests (see Fig. 3-85), air-driven spherical or piercing-type missiles and others. 

A standard device for conducting impact testing is a drop hammer. In a typical test, the sample is mounted horizontally, a heavy pendulum is raised and then released, hitting the sample. The impact viscosity is evaluated as... 

These requirements are verified by a dynamic impact test with a pendulum that impacts the device. In order to pass the test, the pendulum must continue to swing after the impact within a minimum angle of 20 to the vertical. For this reason, outside mirrors for passenger cars (Class IE) typically have a folding mechanism which ensures that the mirror housing deflects appropriately. CMS usually have a smaller camera holder design which does not foresee an installation space for a folding mechanism. 

UN Regulation No. 46 includes some exemptions for the different mirror classes under which the impact test is not required. If, for instance, the installation height for devices of Class II-IV exceeds 2 m, the impact test is not required. In case of Class 111 mirrors for passenger cars, this exemption is practically irrelevant, but there are other configurations which are exempted from the pendulum test ... 

As explained in Sect. 3.2.1, UN Regulation No. 46 includes requirements to address, on the one hand, impacts of occupants on inside mounted devices for indirect vision (e.g. inside mirror Class 1), and on the other hand, impacts of other road users (e.g. pedestrians) with outside mounted devices for indirect vision (e.g. outside mirror Class ID). The impact requirement is verified with a dynamic pendulum test. UN Regulation No. 46 clarifies that monitors of a CMS are exempted... 

Joints often experience impact or shock loads, and their reactions will differ depending on the rheology of the adherend and the adhesive. Another early standard is D-0950, Test Method for Impact Strength of Adhesive Bonds. It involves a relatively simple specimen (Fig. 17), but a special pendulum device is required for application of the impact shear load. 

The manner in which the part is struck with the impact loading device significantly affects the impact results. A pendulum type of impact loading will produce a different result from the one produced by falling-weight or high-speed ball-impact loading. 

The chip impact test is somewhat similar to the Izod impact test. The specimen can be tested using standard Izod pendulum tester. The chip impact test requires the use of a pendulum hammer type of device and a specimen holding fixture. The test specimens are usually 1 in. long x 1/2 in. wide and 0.065 in. thick. The specimens can be prepared either by injection or compression molding or by simply cutting them from a sheet. 

FIGURE 5.1 Charpy and Izod impact specimens, (a) Impact pendulum device, (b) loading of Charpy specimen, (c) loading of Izod specimen, and (d) dimensions of Izod specimen. (Adapted from Tensile Impact Energy to Break Plastics and Electrical Insulating Materials, ASTM Standard DI822, West Conshohocken, PA, 1999.)... 

In recent years there has been much interest in the application of polymer materials at the micro- and nanoscale as microelectronic devices are made smaller and smaller. Constantinides describes an analysis and experiments of materials at the nanoscale. An instrumented pendulum device with a diamond Berkovich indenter was used to indent polymer specimens at a rate of 0.7-1.5 mm/s. The highest impact velocity (1.5 mm/s) corresponded to an impulse energy of 250 nJ. (The Berkovich nanoindenter similar to the Vickers type is normally used for testing the hardness of a material. It has a three-sided pyramid shape. It has also... 

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