Product category:
Accelerometers and Vibration Sensors
News Release from: Measurement Specialties | Subject: EL20-S458
Edited by the Engineeringtalk Editorial
Team on 24 October 2006
Tension sensor survives crash testing
The EL20-S458 seat belt tension sensor is designed for enhanced accuracy and survivability in crash tests.
New from Measurement Specialties, the EL20-S458 seat belt tension sensor is designed for enhanced accuracy and survivability in crash tests Sensors used in automotive crash testing must be designed to withstand high levels of shock and comply with large physical displacements while performing highly accurate measurements
Sensors used for testing seat belt tension, in particular, present special challenges: the seatbelt - and any sensor affixed to the seatbelt - must allow substantial movement during the crash, causing high forces to be applied to the sensor itself, the sensor cable and cable restraints/lead exits from the sensor.
Sharp edges on a sensor can damage the expensive crash test dummy or create measurement errors by snagging on airbag fabric during airbag deployment.
The intrinsic mass of the seat belt sensor, when violently accelerated and decelerated during a crash event, results in F=ma forces which produce error in the sensor output.
Additionally, deformation of the seatbelt and the sensor structure during loading produce inherently nonlinear sensor outputs - on the order of +/-3% of the full scale output of the sensor.
Measurement Specialties, through acquired company Entran, has placed into service hundreds of robust, first-generation EL20 seatbelt tension sensors for more than a dozen years.
Customers attest to the uncommonly high survivability of these instruments in continuous use in hostile test environments.
The second generation EL20 builds on this earlier success by providing enhanced precision and even greater long-term durability.
Whether one is measuring parachute tether loads or using this advanced new sensor for automotive seatbelt test environments, the EL20-S458 provides unparalleled precision, durability and return on investment.
The new device is lighter than its predecessor.
The use of titanium reduces sensor mass and the errors that can result when the sensor is violently accelerated and decelerated during a crash event.
The redesigned axles are offered with two options for easy installation without removing the seat belt.
A knurled axle can be threaded manually, without tools.
For super low mass, ultra high performance applications, reduced mass slotted titanium axles can be threaded with a screwdriver.
The location of the cable has been changed, with the lead now exiting in the direction of belt tension.
The cable is shielded with slice-resistant medical-instrument grade silicone rubber, which slips away from pinch zones.
The cable - the part most frequently damaged - was redesigned for increased durability and user replacement, extending life of the sensor.
All edges have been rounded and all protrusions removed on the EL20-S458 to eliminate snags during dynamic, high displacement crash events.
This clean, smooth exterior protects the investment in crash test dummies and ensures the highest quality data possible.
Upgraded amplifier circuitry is nonlinear in the opposite direction to compensate for the inherent nonlinearity in the instrument.
Linearity has been improved from +/-3 to +/-0.5%.
The amplifier also provides a high-level output improving immunity to electrical interference.
As in any exceptionally hostile test environment, the EL20-S458 should be recalibrated as least annually.
Measurement Specialties provides this recalibration service for customers at a fee.
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