1 1 Department of Mechanical Engineering Smart Materials and Structures Laboratory Spring 2015 ECE Senior Design Topic Development of a Portable Real-Time.

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Department of Mechanical EngineeringSmart Materials and Structures Laboratory

Spring 2015 ECE Senior Design Topic

Development of a Portable Real-Time Bolt Preload Monitoring System using Piezo-ceramic

Transducers

Faculty AdvisorDr. Gangbing Song

Email: [email protected]; Tel: x34525

Graduate Student AdvisorsMr. Seyed Mohammad Parvasi

Email: [email protected]; Tel: x34498Mr. Chenyu Wang

Email: [email protected]; Tel: x34549

Sponsored by Cameron

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Department of Mechanical EngineeringSmart Materials and Structures Laboratory

Background

• Bolt connections are the most commonly used connection element in structures and devices especially in Oil and Gas industry.

• Bolted connections commonly fail due to insufficient/excessive preloads during installation or a loss of axis load (self-loosening) caused by external dynamic loads in service.

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Department of Mechanical EngineeringSmart Materials and Structures Laboratory

Commercial Methods for bolt monitoring

Commercial methods for bolt monitoring include

• Direct measurement The most current conventional techniques in industry for monitoring the bolted joints directly measure the stress between the connected pieces or the strain in the bolt.

• Indirect measurementIndirect measurement on the other hand are driven by ultrasonic technology.

Bolt stress measurement using strain gauge

Conventional application of ultrasonic measurements of bolt connections

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Department of Mechanical EngineeringSmart Materials and Structures Laboratory

Introduction to piezoceramics

Piezoceramics will generate an electric charge when it is subjected to a stress or strain and also produce a stress and strain when an electric field is applied to it in its polarization direction.Piezoceramics can be utilized as both an actuator and a sensor.

In this research, PZT transducers (lead zirconate titanate), a type of commonly used piezoceramic material with high piezoelectric effect, may be used in the form of PZT patches and PZT stack devices to initiate and capture stress waves in bolted connections.

Piezoelectricity

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Department of Mechanical EngineeringSmart Materials and Structures Laboratory

Time Reversal Technique

The time reversal technique is an adaptive wave transmission technique which can focus acoustic/ultrasound waves spatially and temporally in both homogenous and non-homogenous media. Based on TR, the input signal can be focused symmetrically at the excitation point using time reversal (TR) process and the peak value of the output signal shows the focused energy of the signal at the source point.

Complex media

Source

Time Reversal Mirror

Time reversal principle scheme

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Department of Mechanical EngineeringSmart Materials and Structures Laboratory

Bolted connection with PZT patches installed

Proposed Method for Bolt Monitoring

An innovative time reversal technique using piezoelectric transducers is proposed to monitor bolt preload and torque levels in real-time without modifying the bolt joint body.

Two PZT patches mounted on a single lapped bolt joint. Different pre-loads were applied on the bolt joint by a torque wrench. Under each pre-load condition, the time reversal technique was utilized to obtain a focused signal peak.

Relationship between focused signal peak and preload torque

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Department of Mechanical EngineeringSmart Materials and Structures Laboratory

PZT 1: ActuatorPZT 2: Sensor

Previous Achievements

We studied the feasibility of in real-time bolt preload monitoring of every single bolts of a flanged ball valve using time reversal procedure and piezoceramic transducers.

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Department of Mechanical EngineeringSmart Materials and Structures Laboratory

Experiment loads and conditions

• 35 lb.ft torque applied on all the nuts except L1 and C

• Seven distinctive torque levels applied on L1 (5, 10, 15, 20, 25, 30, 35 lb.ft)

• For each torque level on L1, we applied seven distinctive torque levels on C (5, 10, 15, 20, 25, 30, 35 lb.ft)

C : Center nutL1: 1st left nut

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Department of Mechanical EngineeringSmart Materials and Structures Laboratory

The relationship between the focused signal peak and preload torque applied on nut C

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Department of Mechanical EngineeringSmart Materials and Structures Laboratory

Advantages of the proposed method

Compared to currently available methods, the use of time reversal based monitoring through PZT bonded tapes offers advantages include:

• Hassle-free setup

• Requires no structural modification to the bolted connection.

• Simultaneous monitoring of all bolts in near real-time speed

• Low cost and simple production for PZT-patches and flexible polymer tapes

• The time reversal procedure used in this method is highly robust and can withstand high levels of noise in the system

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Department of Mechanical EngineeringSmart Materials and Structures Laboratory

Project Goal

The objective of the proposed project is to design and build a portable, reliable, hassle free actuating/sensing device for real-time monitoring of bolt pre-loads in flanged structures.

Major Tasks:

• Two flexible polymer tapes, one for actuation and the other for sensing, are fabricated separately with lengths matching the circumferences of the flange and the valve body (i.e. one tape for each circumference).

• The actuator and sensor tapes will wrap around the circumference of the flange and valve body, respectively, and will have PZT patches installed on the inner surface of the tapes to act as the actuating/sensing transducer.

• The number of PZT patches will correspond to the number of bolts in the valve of interest and will have a spacing equal to the distance of two consecutive bolts.

• A DAQ board (NI systems) will be used for the generation and measurement of signals for the PZT patches.

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Department of Mechanical EngineeringSmart Materials and Structures Laboratory

What you will learn and Deliverables

What you will learn• Piezoceramic transducers • Active sensing method• Time reversal technique• Embedded system • Real time monitoring techniques

Deliverables:• A portable and functional device or monitoring protocol that can be

economically and widely applied to monitor bolt connections under most conditions.

• Preliminary database listing desired time reversal peak values for different size and shape bolted connections.

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Department of Mechanical EngineeringSmart Materials and Structures Laboratory

Questions ?