The George E. Brown, Jr. Network for Earthquake Engineering Simulation

Equipment

1. Facility
2. Centrifuge
3. In-Flight Robot
4. Laminar Boxes
   1. 1D Large Laminar Box
   2. 1D Small Laminar Box
   3. 2D Laminar Box
5. Shakers
   1. 1D Shaker
   2. 2D Shaker
6. Split Boxes
   1. Dynamic Split Box - 1H 1V
   2. Dynamic Split Box - 2H
7. Rigid Boxes
8. High-Speed Camera
9. Sensors
10. Data Acquisition

Sensors are a critical component of physical modeling. They produce information that is used to quantify and understand physical phenomena. The centrifuge facility at Rensselaer Polytechnic Institute uses many types of sensors and instrumentation. The following sections introduce traditional and advanced sensors, with the term advanced describing those which require separate data acquisition hardware or software.

Traditional Sensors

The geotechnical centrifuge facility at Rensselaer maintains an inventory of sensors and instrumentation that are available for use. These include:

• Accelerometers
• Laser Displacement Transducers
• Linear Variable Differential Transformers (LVDTs)
• Pore Pressure Transducers
• Strain Gauges (120 Ω and 35 Ω Bridge Completion)

Detailed information regarding the sensor inventory may be found at NEEScentral. In addition to the sensors maintained in inventory, the data acquisition hardware supports the following:

• Load Cells
• String Potentiometers
• Thermocouples with Cold Junction Compensation
• Voltage or Resistance based Instrumentation

Specifications

Accelerometers

Manufacturer	PCB Piezotronics
Model	353B17
Connector	BNC
Conditioner	SCXI-1531

Laser Displacement Sensors

Manufacturer	Keyence
Model	LB-11 (Sensor) LB-70 (Conditioning Unit)
Connector	RJ12
Conditioner	SCXI-1102c

LVDTs

Manufacturer	Schaevitz
Model	MHR Series
Connector	RJ12
Conditioner	SCXI-1540 with SCXI-1315 Accessory

Pore Pressure Transducers

Manufacturer	GE Druck
Model	PDCR 81-3478
Connector	RJ12
Conditioner	SCXI-1520 with SCXI-1314 Accessory

Strain Gauges

Manufacturer	Vishay
Model	CEA 13 032UW 120 and EP 08 125AC 350
Connector	RJ12
Conditioner	SCXI-1520 with SCXI-1314 Accessory

Advanced Sensors

Traditional sensors produce a one-dimensional data stream. Advanced sensors are those which perform outside the specification of the traditional data acquisition hardware. These include:

• Tactile Pressure Sensors
• Bender Elements

Tactile Pressure Sensors

Each tactile pressure sensor is composed of approximately 2000 sensing elements (sensels). They are a resistance based technology and can be calibrated over a wide range of pressures. Due to the two-dimensional nature of the data stream, the sensors require separate data acquisition hardware and software. The hardware, called a “handle”, is standardized to accept many sizes and sensor models.

The tactile pressure sensors, data acquisition hardware, software, and calibration device are produced by Tekscan. Two types of sensor are available for use: high-resolution and high-speed. High-resolution sensors contain nearly 2000 sensing elements and a maximum sampling rate of 275 Hz. High-speed sensors have 280 sensels and a maximum sampling rate of 1400 Hz. Models used in the Rensselaer centrifuge include:

• High-resolution: 5101, 5250 and 5315
• High-speed: 5501

Bender Elements

Bender elements are piezo-electric transducers that produce and detect mechanical waves is a soil medium. These sensors are typically sampled at a frequency above 300 KHz and require separate hardware and software. They are used to determine shear and compression wave velocities in a centrifuge model.

Manufacturer	Piezo Systems, Inc.
Model	5A4E Nickel Electrode Custom Cut
Material	Navy Type II Lead Zirconate Titanate
Dimensions	12.7 × 8.0 × 0.6 mm
Connector	RJ-174
Hardware	M-series PXI MFDAQ