Charpy Test or Impact test

[jdm2008]

Hellow

I am testing the impact strength of a two piece plastic(poly carbonate) cylindrical container(they are threaded together). There is a ciricular slot and and the rest of the the container is filled with lead. It is pretty clear that the plastic will fail at the threads. I do not have access to expensive equipment so I must test test with a simple system. Is there any advantage of the charpy teset over the drop test(just attaching a weight to a rope and dropping it on the threads), in this instance? The samples will be identical(except for the material we are deciding between).

 

[jdm2008]

Just as a follow up. In the drop test the weight will be attached to a rope and pulley...

 

[redpicker]

The Charpy test is typically used on metals. I have never heard of it being used on plastics, but I don't know why you couldn't...

The Charpy test has some very controlled conditions. The size of the specimen, geometry of the striker, the speed of the striker, etc... The Chapry test will also report the amount of energy absorbed during the fracture.

With the drop test, you can vary most of these conditions to meet your situation. The results between samples tested under the same conditions should be comparable, but you would have a hard time comparing your results with those of another tester using different conditions.

rp

 

[stanweld]

Instrumented Charpy impact tests have been used on plastic materials. Because you are testing the finished threaded part, you should use the simpler test as you described.

 

[TVP]

jdm2008,

FYI, Charpy testing of plastics is commonplace. Here are some relevant standards:

ASTM D6110-10 Standard Test Method for Determining the Charpy Impact Resistance of Notched Specimens of Plastics

ISO 179-1 Plastics -- Determination of Charpy impact properties -- Part 1: Non-instrumented impact test

ISO 9854-2 Thermoplastics pipes for the transport of fluids -- Determination of pendulum impact strength by the Charpy method -- Part 2: Test conditions for pipes of various materials

 

[CoryPad]

One further piece of information, Izod impact testing of plastics is the most common method.

ASTM D 256 Standard Test Methods for Determining the Izod Pendulum Impact Resistance of Plastics

ISO 180 Plastics -- Determination of Izod impact strength