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LabVIEW based SCADA system for Impact Test Instrument for compliance and conformity test of Helmets

free-fall

Impact Tower with guided free-fall and head-form for testing helmets

The impact attenuation performance of a helmet is evaluated by releasing the impactor from a specific height in guided free-fall onto an impact head form. The forces transmitted to the head form are measured with integral load sensor and accelerometer and compared to performance limits.

A large batch of helmets can be easily tested by entering the identification number in to the Database through the LabVIEW VI. The number of impacts, test sites, description of impact location, impact anvil, drops mass, drop velocity; type of standard and type of head-form used are variables that can be set for each helmet tested. (The drop tower complies with helmet test standards stipulated by ASTM, IS, EN, ANSI, Snell, Dot, and other organizations).

Prior to the commencement of testing, database fields incorporated in the SCADA simplify record keeping and report generation once testing is completed. Information such as sizing, helmet identification, conditioning environments and test standards can be entered and stored with the test data.

The user interface

SCADA-UI

The SCADA is specially designed for helmet certification and performance testing. The user interfaces directly with helmet impact tester via PC based data acquisition and motion control boards. The VI controls the impact tower and collects test measurements from sensors.

Test Configuration

Prior to the commencement of testing, helmet identification, conditioning environments and test standard to be entered and stored with the test data.

Configure Test

Pressing “Configure Test” window invokes the editor menu. Configure required test standard or specification. All the standards have test parameters Mass (g), Heights (m), Velocity (m/s), ‘g’ (m/s²), maximum Force, ‘g’ max limit that will be stored in database.

Set to zero position

Before conducting test it is require to do set zero mark position of impactor as reference point for calculating height while conducting test.

Moving the slider using the VI controls

Impact Test for Compliance Test & Check of Helmets

At Zero position, the impactor should be just touching the top of helmet

Follow steps for setting zero position:

  1. First magnetize drop carriage slider by pressing “MAGNETIZE” button (Slider magnetized and indicator glow red on slider)
  2. Keep pressing “IMPACTOR LOWER” button and let the slider move in downwards direction till it reaches impactor striker plate. The moment the impactor touches striker plate, the green light on slider glows; at that point of time release IMPACTOR LOWER KEY. (The interlock will prevent overshoot)
  3. Click & keep pressed “IMPACTOR RAISE” button, the drop carriage slider with the impactor striker moves up with high speed. Release the button before it touches upper end of impactor rod.
  4. Use the motor’s low speed to fine tune.
  5. Click “SET TO ZERO” button to mark zero position(displacement indicator counts ‘set to zero’)

Certain specifications about the impact assembly, head-form, anvil etc. are available in relevant standards and that description is out of scope of this blog.

Test Results to check compliance of the helmet to the relevant standard

The results from each test are instantly displayed both numerically and graphically. The load (Kn) / time graph and Acceleration (g)/time graph will be displayed as per the user requirement- either Shock absorption or Acceleration test. The data are displayed numerically for Velocity@impact, Peak Force, and peak Acceleration. The data are also saved to disk for review at a later date.

conformity of Helmet to relevant standard using LabVIEW

The user can test the conformity of Helmet to relevant standard using the reporting module. It is also possible to print out or export to HTML/Word/pdf.

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