Objective

To simplify the Markl test procedure and improve accuracy and repeatability.

Steps

Inclusion of Futek pancake load cell in the Markl hydraulic loading arm. The Futek load cell has a fatigue rating and a maximum load of 25,000 lb with a displacement of 0.002”. The Futek load cell should be accurate dynamically to within 50-to-100 lb. The inclusion of the load cell in line with the loading arm permits in place load deflection curve generation and constant, real time monitoring of the load application through the test cycle. Eliminating the manual load-deflection test procedure will improve the accuracy of the test and decrease the total time to completion.
Addition of a high speed Data Acquisition System (DAQ) with 1Mhz sample rate. The DAQ system will log the applied load, displacement, and strain throughout a fatigue test.
Custom software control system for the Markl fatigue test machine. The new DAQ system will be interfaced to the Markl control system through a custom software interface developed by PRG to allow real-time feed-back control of the fatigue tests. The new software interface will allow the Markl machine to be operated in displacement control mode, load control mode, or strain control mode. Additionally, the new software system will allow for user defined laoding histories.

The Futek pancake load cell is shown with the refurbished Markl hydraulic cylinder below. The linkage was designed to be removed, if the original Markl configuration test should be run, (without the load cell.)

Futek Pancake Load Cell Installed with Markl Hydraulic Cylinder

Disassembled Components Hydraulic Load Cell Components

Futek Load Cell Specifications

Rated Output - 2mV/V nom.
Safe Overload - 150% of Rated Output
Excitation (VDC or VAC) - 20 Max
Bridge Resistance - 350 ohm
Nonlinearity - +/-0.1% of Rated Output
Hysteresis - +/-0.2% of Rated Output
Nonrepeatability - +/-0.02% of Rated Output
Creep - +/-0.02% of Load
Operating Temp. - -60ºF to 200ºF
Material - 17-4PH / Alloy Steel
Weight - 9 lbs