MOD-SHOCK™

The test is a simplified forced vibration test of the pile, the forced vibration test being developed by Davis and Dunn in the early 70”s. The forced vibration test was a good NDT method of testing piles, but due to the large volume of equipment required for the test it was essentially an unpractical method of testing piles.

John Higgs in association with others embarked on a way to copy the vibration test without the need for the forced vibration. Over a number of years the Modified Shock test was developed and the latest version of this is the MOD-SHOCK™, exclusively developed by Integrity Testing Pty. Ltd.

In essence the test uses the broad-spectrum frequency response from a hammer blow to the element under test, as the substitute to the forced vibration. The operator places a transducer on the element under test and then imparts sufficient vibrations into the element with hammer blows. The reflected signals are captured by the transducer and via a cable stored in a Notebook computer for later analysis

The analogue signal is converted into a digital format and the signal under goes Fourier transform. The main components of this transform being a Mechanical Admittance plot and a frequency look up table, these being the main parameters obtained in a forced vibration test.

From the mechanical admittance plot the load/deflection values can be obtained as the plot is the solution of the Wave equation of motion and measures the resistance to the hammer blow. From the frequency look up tables the parameters of the pile model can be obtained in both directions, giving the two points to be able to plot a 2D model

This is the basic concept of the system but it has evolved into many applications and we list them below, these all being well proven techniques and total tests for the Mod-Shock in all of its forms exceed 1 million in the past 3 decades it has been in use.

Pile testing for all types of materials, steel, timber and concrete and pile types, new and ones in existing structures.
Column testing once again for steel, timber and concrete, new or in existing structures.
Rock bolts, strands and tie rods either new or in existing structures.
Investigation of underground sewers, pipelines etc.
Bollards for shipping, more details in the marine section.

We recommend if you need more in depth details go to www.mod-shock.com.