Pendulum Impact Hammers

How Pendulum Impact Hammers Work


Principle of Operation
The hammer energy determines the velocity of the impact tests according to ISO, ASTM and equivalent standards. Pendulum hammers can be un-instrumented or instrumented. Instrumented hammers, combined with a Data Acquisition System and Software, provide a more complete representation of an impact than an individually-calculated value.

Instrumented pendulum impact testers enable research and development and advance quality control to evaluate material failures in depth. The load on the specimen is continuously recorded as a function of time and/or specimen deflection prior to fracture. Many details, including incipient damage points and ductile-brittle transition zones, become clearly visible in the data.


 Non-instrumented Instrumented
Elastic modulus
✔
Yield point
✔
Energy adsorbed by the specimen ✔
(overall energy loss)		 ✔
(integration of force)
Force at fracture
✔
Deflection at fracture
✔
Kind of fracture
✔
Temperature dependence ✔ ✔

Pendulum Hammers
Hammer Thermal Image
Main Features and Benefits

Instron’s innovative pendulum hammer design evolved from two primary needs: accuracy and rigidity.

Instron’s patented charpy hammer structure, machined from one piece of metal alloy plates, ensures:

  • Incomparable rigidity
  • Solid connection to the encoder shaft
  • Negligible vibrations
  • Reduced energy losses due to wind friction, thanks to a flattened shape.

Equipped with an ergonomic quick-change mechanism, the hammers can be easily changed without the use of tools or screws and the wedge system assures a firm fixing. The automatic hammer recognition and in-built calibration procedure avoid any risk of error. This system consists of three pins that are positioned on the hammer and are read by the photocell system of the instrument.

When the calibration is completed (after each hammer change), the instrument has automatically performed the following operations:
1. Encoder zero-setting
2. Hammer recognition (its proper data is shown in the touch screen control panel)
3. Calculation of lost energy, shown on a green background if the value measured is lower than the maximum value allowed by the standard

All Instrumented hammers are free of wire.


Electric Icon

The hammer is equipped with a miniaturized slip ring to transmit the electric signal with the lowest friction, avoiding spring effect of connection cables of the instrumented hammers


Stopwatch Icon

The set-up time and hammer connection is easy and it takes less then 5 minutes compared to 20/30 minutes for the hammers with cable connection


Video Icon

Any downtime due to hammer connection set up and damages to the wire are eliminated




Application Range


Polymers testing according to ISO 179-1, DIN 53453, DIN 53753 and BS 2782-359

Potential un-instrumented
hammer energy		 Impact velocity
J ft/lb m/s ft/s
0.5 0.37 2.9 9.5
1.0 0.74 2.9 9.5
2.0 1.48 2.9 9.5
4.0 2.95 2.9 9.5
5.0 3.69 2.9 9.5
7.5 5.53 3.8 12.5
15.0 11.06 3.8 12.5
25.0 18.44 3.8 12.5
50.0 36.89 3.8 12.5
Potential instrumented
hammer energy		 Load capacity Impact velocity
J ft/lb kN lbs m/s ft/s
5.0 3.69 2 450 2.9 9.5
7.5 5.53 2 450 3.8 12.5
15.0 11.06 2 450 3.8 12.5
25.0 18.44 4 900 3.8 12.5
50.0 36.89 4 900 3.8 12.5


Polymers testing according to ASTM D6110

Potential un-instrumented
hammer energy		 Impact velocity
J ft/lb m/s ft/s
0.5 0.50 3.46 11.35
1.0 0.74 3.46 11.35
2.7 2.0 3.46 11.35
5.4 4.0 3.46 11.35
10.8 8.0 3.46 11.35
21.6 16.0 3.46 11.35
50.0 36.9 3.46 11.35
Potential un-instrumented
hammer energy		 Load capacity Impact velocity
J ft/lb kN lbs m/s ft/s
5.4 4.0 2 450 3.46 11.35
10.8 8.0 2 450 3.46 11.35
21.6 16 4 900 3.46 11.35
50.0 36.9 4 900 3.46 11.35

Polymers testing according to ISO 180, ASTM D256, ASTM D4812

Potential un-instrumented
hammer energy		 Impact velocity
J ft/lb m/s ft/s
0.5 0.37 3.46 11.35
1.0 0.74 3.46 11.35
2.75 2.0 3.46 11.35
5.5 4.0 3.46 11.35
11.0 8.1 3.46 11.35
22.0 16.0 3.46 11.35
50.0 36.89 3.46 11.35
Load capacity Potential un-instrumented
hammer energy		 Impact velocity
kN lbs J ft/lb m/s ft/s
2 450 5.0 3.69 3.46 11.35
2 450 11.0 8.1 3.46 11.35
2 450 22.0 16.0 3.46 11.35
2 450 50.0 36.89 3.46 11.35

Polymers testing according to ISO 8256

Potential
hammer energy		 Impact
velocity
J ft/lb m/s ft/s
0.5 0.37 2.9 9.5
1.0 0.74 2.9 9.5
2.0 1.48 2.9 9.5
4.0 2.95 2.9 9.5
7.5 5.53 3.8 12.5
15.0 11.06 3.8 12.5
25.0 18.44 3.8 12.5
50.0 36.89 3.8 12.5
 
 
Polymers Pipe Testing according to ISO 7628 and ISO 9854, either complete segments or small sections of pipes are ideal for testing on a pendulum in a 3-point bend configuration similar to the Charpy tests.
Sample diameter dimensions up to 25 mm (0.98 in) can be tested with hammer energies of 7.5 - 15 J (5.6 - 11.1 ft-lbs) or 50 J (36.9 ft-lbs), as defined in the ISO standards.

 
Metals testing according to ASTM E23, ISO 148, and DIN 50115

Potential un-instrumented
hammer energy		 Striker radius Impact velocity Testing standards
J ft/lb mm in m/s ft/s
50.0 36.9 8 0.314 3.8 12.5 ISO 148 and ASTM E23
50.0 36.9 2 0.079 3.8 12.5 ISO 148 and DIN 50115
For indirect verification to metals standards only low-energy specimens may be used.
Potential instrumented
hammer energy		 Load capacity Striker radius Impact velocity Testing standards
J ft/lb kN lbs mm in m/s ft/s
50.0 36.9 8 1800 8 0.314 3.8 12.5 ISO 148 and ASTM E23
50.0 36.9 8 1800 2 0.079 3.8 12.5 ISO 148 and DIN 50115
For indirect verification to metals standards only low-energy specimens may be used.