The compression machines tested for high stability meet the stringent requirements of the:
EN 12390-4 | BS 1881:115 | DIN 51220 | UNI 6686, part 3 | NF P18-411 | UNE 83304 | ASTM C39 | AASHTO T22
The machines are manufactured with specific quality features (processing, tolerances) of frame, piston/cylinder group, spherical seat, compression
platens, distance pieces etc., conforming and meeting the high stability verification. (force distribution).
The conformity of the stability is certified with the verification of the self-alignment (foot-meter test) of the machines components and the
restraint on movement of the upper spherical seat/platen, by using a special electric strain load column at 5 measuring points which is connected
to its suitable datalogger (technical details: see p. 325)
An incorrect and not uniform load application to the specimen causes irregular, unsatisfactory and premature failure. The obtained
compression resistance can be substantially lower than the effective resistance.
The most important feature of the high stability frames is their uniform distribution of the applied load on all the specimen surface
under test. The sample breakage is satisfactory and the strength results are correct, high and true.
The four columns frame is prestressed on 8 ring nuts and the clamping is obtained and checked by a dynamometric spanner, allowing to get
a very high stiffness and stability on all load range and to keep these features in the time.
The spherical seat, in oil bath with null end float, is studied and manufactured to grant, during the starting phase of the test, an accurate
self-alignment without frictions of the upper compression platen to the specimen. By applying the load, the ball seating assembly locks and
keeps the position until the specimen’s failure.
Piston and cylinder are coupled with high quality packing set.
Compression platens are hardened over 55 HRC and rectified.
Available in the capacities: 2000 kN | 2000 kN blocks | 3000 kN | 3000 kN blocks | 4000 kN | 5000 kN
Load measuring system: Bourdon type gauge
Digitec or Cyber-Plus Evolution graphic display unit
Servo-controlled automatic system Autotec or Servo-Plus Evolution with optional Servo-Strain and Elastic Modulus determination.
Described and pictured in the next p. 262…281