SSM SUITE

The SSM-Suite™ Software package consists of six programs: 

  • Automated Ball Indentation® 
  • Indentation-Creep™
  • Indentation-Stress-Relaxation™
  • Fiber Push-out
  • Tensile
  • Haggag Toughness Method (HTM) for Fracture Toughness

In addition to these programs, an X-Y positioning program is provided for positioning of the sample’s test location underneath the indenter to within 0.0002 inch (5 microns of a meter).

The SSM-Suite software is written in National Instruments’ LabView® graphical language. This allows real-time graphics capability during the test and for data analysis.

The common features of the SSM-Suite™ package are:

  • Full computer control of the Stress-Strain Microprobe® (SSM) system in closed-loop operation in both load and displacement control.
  • Provide user-determined and built-in software limits on both allowed maximum load and maximum displacement in order to prevent the damage of: any sensor (load cell, displacement transducer), test specimen or structure, and the indenter.
  • Smooth transition from load control to displacement control and vice versa.
  • Full computer control of all motor speeds and specimen unloading at the end of the test.
  • Variable data acquisition rates up to a maximum of 500 data points per second.
  • Real-time digital and graphical display of the load and displacement signals during the test.
  • Tabulated data and graphs in either English or metric (SI) at the user’s choice for each single test. Summary tables of multiple test results are also provided in either English or metric (SI) units. Summary tables can be printed or saved as an ASCII files. Binary data files can be saved in ASCII format.
  • Multiple overlays of graphs to allow instant comparison of the raw-data and the results of several mechanical tests.

Automated Ball Indentation®  (ABI® ):

For metallic materials, the ABI®  program determines:

  • Yield strength,
  • True-stress versus true-plastic-strain data pairs up to a true-strain of 20%,
  • Power-law regression of flow properties to calculate the strain-hardening-exponent (n) and the strength coefficient (K) as described in ASTM Standard Test Method E-646-93,
  • An estimate of the ultimate tensile strength from the power-law regression results,
  • Calculation of static fracture toughness of ferritic steels in the transition temperature region based on the Haggag Toughness Method (HTM) using the ABI® -measured indentation load-depth data and a critical fracture stress model
  • ABI® -Hardness for the indenter size used

The program allows the overlay of the true-stress/ true-plastic-strain curve from the nondestructive and localized ABI®  test and the corresponding curve from the destructive tensile test conducted on the same metallic material. This capability provide instant comparison of stress-strain curves from the ABI®  and the Tensile tests. Overlay of raw data or test results from multiple ABI®  tests allows the determination of material variability at various test locations (a desired capability for welds and heat-affected-zones).

Indentation-Creep™: 

Performs a localized Indentation-Creep test with either a spherical indenter or a flat-end cylindrical indenter. During the Indentation-Creep test, the stress is held constant at the user’s selected stress value and the indentation creep strain is monitored for the desired duration of the test (few minutes to several days or months). A real-time display of the load, depth, stress-versus time and strain versus time are provided, in addition to the digital display of the load and depth values, during the performance of the test. The data, test results, and graphs are saved for printing and/or further analysis. Also, the binary data can be converted to an ASCII output file at the user’s command. The closed-loop operation of the SSM system allows: (a) precise feed back and computer-control of the test, and (b) maintaining the hold-value of the stress within the delta-stress value (small percent variation from the hold stress value) as specified by the user.

Indentation-Stress-Relaxation™: 

Similar to the Indentation-Creep program, except that the strain (instead of the stress) is held constant at the user’s selected strain value and the indentation stress-relaxation is monitored for the desired duration of the test (few minutes to several days or months). A real-time display of the load, depth, stress-veers time and strain versus time are provided, in addition to digital display of the load and depth values, during the performance of the test. The data, test results, and graphs are saved for printing and or further analysis. Also, the binary data can be converted to an ASCII output file at the user’s command. The closed-loop operation of the SSM system allows: (a) precise feed back and computer-control of the test, and (b) maintaining the hold-value of the strain within the delta-strain value (small percent variation from the hold strain value) as specified by the user.

Fiber Push-Out:

This program allows the push-out of a single fiber in uniaxial fiber composites. The program provides a real-time display of the load-depth data so that fiber push-out can be monitored and the test terminated appropriately. The data can be saved as an ASCII file for further analysis by the user’s other routines or software packages.

Tensile:

This test is performed according to American Society of Testing and Materials (ASTM) standards E 8 and E 646 (standard test methods for: tensile testing of metallic materials, and the strain-hardening exponent, respectively). The program allows the overlay of the true-stress/true-plastic-strain curve from destructive tensile test and corresponding curve from the nondestructive and localized ABI®  test conducted on the same metallic material (e.g. ABI®  tests can be conducted on the end tab of flat tensile specimens).

 

Fracture Toughness:

Performs conventional, destructive fracture toughness tests according to ASTM standard E 1820-96 using all specimen geometries.