Direct/residual Shear Machine

ASTM D3080, AASHTO T236, BS 1377:7, NF P094 071-1/2, CEN-ISO/TS 7982-10

The AUTOSHEAR machine is controlled by a microprocessor system which reads and processes horizontal force and displacement readings and manages the motor and safety limits via a closed-loop control system.The unit provides the following important features:

Features

Technical specifications

Microprocessor-controlled drive system
Large 240 x 128-pixel display
Test speed, direction and cycles (up to 10) programmable using the keyboard
Rapid approach and automatic positioning
Infinitely variable speed from 0.00001 to 11.00000 mm/min
Possibility to set different speed and direction (forward and reverse) in the residual shear test
Three analogue channels: one for load cell, and two for displacement transducers, 130,000-point resolution
Different protocols for downloading data to PC through RS-232 serial port
Standard load ring and dial gauges also compatible for manual recording
Automatic running of tests
Closed-loop control of test speed
Different calibration functions (linear and polynomial)
Language selection
Continuous monitoring and display of horizontal force, vertical and horizontal displacement
Maximum horizontal displacement limit (20 mm) controlled by mechanical and optical safety switch
Different recording modes, including linear, exponential (square root) and logarithmic
High capacity data memory (up to 1000 lines of data)
RAM memory with battery back-up with clock/calendar, operative even when theunit is switched off

The design of the horizontal loading system provides rigid linear alignment of the loading ram, shear box and force measurement system, ensuring that the horizontal shearing force is transmitted along the shearing plane of the specimen. Techno-polymeric material of excellent quality and high resistance has been used for the carriage of the shear box. It offers excellent resistance to corrosion and wear and tear, and it is resistant to all chemicals found in soil specimens. The carriage is light- weight and easy to clean. The machine is supplied without load cell, transducers for horizontal and vertical displacement, shear box assembly and weights. All these items have to be ordered separately - see Accessories. The machine can also be fitted with mechanical (analogue) measuring devices. The microprocessor control system allows the machine to work as an automatic stand-alone unit: the test measurements (force and displacement) are directly displayed and stored in the unit memory according to pre-set recording modes. The PC is only required once the test is completed, to download the test data via the RS-232 port. The data can be processed using the Direct and residual shear Geo-Analysis templates - see Accessories.
	Detail of shear box carriage made of high resistance techno-polymeric material

Accessories
Electronic measuring devices
27-WF0377/ST	Load cell, 5 kN capacity, complete with adapters.
30-WF6207	Linear potentiometric transducer, 10 mm travel for vertical deformation, complete with mounting block.
30-WF6208	Linear potentiometric transducer, 25 mm travel for horizontal displacement, complete with mounting block.

Data processing software
30-WF6016/T2	Direct and residual shear Geo-Analysis templates conforming to BS 1377:7.
30-WF6016/T9	Direct shear Geo-Analysis template conforming to ASTM D3080.

Mechanical (analogue) measuring devices

Shear box assemblies

Weight set



Example of a direct shear test processed with the 30-WF6016/T2 Geo-Analysis template (BS standard): the top plot shows shear stress versus horizontal displacement; the bottom plot shows change in specimen height versus horizontal displacement