Optical Monitoring and Control of Bolt Tightening

Dr. Sayed Nassar, AdvisorAidong Meng

Objectives and Methodology• Develop optical monitoring and control method for bolt tightening• Use 3-D Electronic Speckle Pattern Interferometry technique • Establish Torque-Tension-Deformation correlation • Determine a proper clamp load and tightening strategy

3-D Electronic Speckle Pattern Interferometric sensor

Results

Test Setup

Nut

Load Cell

Test Coupon

M12 Bolt

Fastener Head

Schematic of single bolt joint

The bolted joint is fixed by a vice

Out-of-plane deformation field corresponding to 26 KN clamp load

Deformation profile along line L1

Deformation profile along line L2

0

0.2

0.4

0.6

0.8

1

1.2

1.4

0 5 10 15 20 25 30

Clamp load F(KN)

Def

orm

ation

w(u

m)

Bolt 1

Bolt 2

Bolt 3

Bolt 4

Bolt 5

Bolt 6

Tension-deformation correlation

z y

x

Laser

Beamsplitter

PZT

CCD array Lens

Reference

beam

Object beam

Measuring direction

Before loading

After loading

Measuring

object

Schematic diagram of ESPI for out-of-plane deformation measurement