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The Benefits of Automated Shear Testing

Apr 28 2014

Understanding shear strength is vital to the engineering properties of any structural project. Shear testing determines the strength of a material and records the specific strains a substance can take allowing the technician to understand how the sample will ‘behave’ in its relative field.

What Are The Benefits of Automated Shear Testing?

The traditional method of Shear Testing involved a Load Frame fitted with a Shearbox containing the sample to be sheared and a lever arm with hangar for adding weights to apply Vertical Load as and when required, to consolidate the sample. Some form of mechanisation moved the top half of the Shearbox after Consolidation to shear the sample. A load ring with mechanical dial gauge was used for Horizontal Load measurement and mechanical dial gauge transducers were used for measuring Horizontal and Vertical Displacement change.

Consolidation and Shear readings were taken on a periodic basis which required the laboratory technician to be on hand with a clipboard and datasheets to record the different Shear data when required throughout the Test

Semi-Automation

The VJ Tech Shear TEST took Shear Testing to a new level. A stepper motor accurately controls movement and has a control box on the Load Frame enabling the laboratory technician to set speeds and rates of movement and carry out other functions (such as Transducer calibration).

Additionally, new hardware was developed that assisted the laboratory technician in many ways. A Load Cell replaced the Load Ring (for Horizontal Load) and LSCT or Potentiometric Transducers replaced Mechanical Dial Gauges for both Horizontal and Vertical Displacement measurement.

The advances in computing power meant that software could be developed to control the different stages of the Shear test representing a huge step forward.

VJ Tech Electronic Data Loggers enabled Horizontal Load, and Horizontal and Vertical Displacement measurements to be recorded as specified and then sent to the computer via an RS232 connection.

The renowned Clisp Studio csShear software module running on the computer is able to;

  • Conform to all major international geotechnical standards
  • Set up individual tests based on the Client, Job, Borehole and Sample
  • Set up and Control the different Instruments and Transducers used in the Shear Test
  • Calibrate the Transducers when required
  • Input Specimen details and automatically calculate related Dimension and Moisture details
  • Set the Consolidation stage starting conditions, data logging parameters and the stopping conditions
  • Set up the Shear stage starting conditions, data logging details and stopping criteria
  • Display live views of sensor readings and status
  • Display live data views, graphs and tables as the test progresses
  • Provide complete results data which can be exported to external data processing packages for further manipulation if required
  • Produce a number of predefined presentation reports summarising all salient geotechnical results

Although a large part of the Shear testing procedure was automated, the laboratory technician was still required to intervene to add weights to the hangar, when an increase in Vertical Load was required. Obviously, there was, and still is a need to remove the holding pins from the Shearbox before starting the shear stage of the test.

Increased Automation and Other Advances

The introduction of the ShearTEST Advanced obviated the need for a Datalogger because the Control Box has 4 analogue input channels, enabling load and displacement data to be logged and then forwarded to the computer. However, there is still a need for weights to be added manually.

When VJ Tech introduced the ShearSCAN 2 to the market, automation was markedly increased by utilising the pneumatic loading concept for applying the vertical load to the sample when carrying out shear testing. This eliminated the need for the numerous weights used in dead weight systems thus freeing up laboratory space and improving health and safety. Because the ShearSCAN 2 is a self-contained table-top model, the purpose built support stand enables the system to be wheeled around the laboratory easily if required.

Now the shear test can be fully automated (except for removal of the Shearbox holding pins), making the laboratory far more efficient and freeing the technician to perform other duties while the test is running.

The VJ Tech electro-mechanical/hydraulic large shear box is specifically designed for direct and residual shear testing on large specimen sizes up to 300mm square and has a built-in four channel data logger for automatic data acquisition. The horizontal load (up to 100kN) is applied electro-mechanically and the vertical load (up to 50kN) is applied using a hydraulic actuator, meaning that the test can again be automated as far as possible.

Speak To VJ Tech

Here at VJ Tech we are passionate in providing the highest standard of shear testing systems providing you with the best results. Visit our brochure website to see our full range of shear testing solutions.

We are available for you to contact so please call +44 (0) 118 945 3737 with any enquiries.

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