Transducer senses displacements of panels subjected to vibration

Inductive vibration sensor measures the surface displacement of nonferrous metal panels subjected to vibration or flutter. This transducer does not make any physical contact with the test panel when measuring

Submicron Deformation Field Measurements II: Improved Digital Image Correlation

This is the second paper in a series of three devoted to the applicaiton of Scanning Tunneling Microscopy to mechanics problems. In this paper improvements to the Digital Image Correlation method are outlined, a technique that compares digital images of a specimen surface before and after deformation to deduce its (2-D) surface displacement field and strains. The necessity of using the framework of large deformation theory for accurately addressing rigid body rotations to reduce associated errors in the strain components is pointed out. In addition, the algorithm is extended to compute the three-dimensional surface displacement field from Scanning Tunneling Microscope data; also, significant improvements are achieved in the rate as well as the robustness of the convergence. For Scanning Tunneling Microscopy topographs the resolution yields 4.8 nm for the in-plane and 1.5 nm for the out-of-plane displacement components spanning an area of 10 μm x 10 μm

Joule Expansion Imaging Techniques on Microlectronic Devices

We have studied the electrically induced off-plane surface displacement on two microelectronic devices using Scanning Joule Expansion Microscopy (SJEM). We present the experimental method and surface displacement results. We show that they can be successfully compared with surface displacement images obtained using an optical interferometry method. We also present thermal images using Scanning Thermal Microscopy (SThM) technique to underline that SJEM is more adapted to higher frequency measurements, which should improve the spatial resolution.Comment: Submitted on behalf of TIMA Editions (http://irevues.inist.fr/tima-editions

Injection Locked Lasers as Surface Displacement Sensors

In an age where engineered materials are becoming common place in the competitive world market, the manufacturer using engineered materials can not afford to waste material in the manufacturing process. The quality control techniques must become real time and on-line to reduce material waste and to reject unacceptable components before complex processing is performed on them. Once the quality control techniques become real time and on-line, the techniques can be incorporated into a feedback loop. The feedback loop can then be used to monitor and adjust the relevant parameters during the manufacturing process to assure component compliance to the desired specifications. To help usher in the era of “smart” manufacturing processes, new reliable and non-contacting NDE systems must be developed

Surface-Displacement Imaging Using Optical Beam Deflection

Important information on subsurface material parameters and structure is contained in the dynamics of surface motion. One of the most important techniques in quantitative nondestructive evaluation is optical sensing of surface displacement; it is noncontact, sensitive, fast, and capable of high spatial resolution. Laser interferometers in various configurations provide the ultimate in sensitivity [1]; however, due to their complexity and lack of flexibility, they may not be the first choice in applications where ultimate sensitivity is not required

Investigating the thermal stability of 1-3 piezoelectric composite transducers by varying the thermal conductivity and glass transition temperature of the polymeric filler material

The thermal behaviour of a number of 1-3 piezoelectric composite transducers is discussed. In particular, devices manufactured from a polymer filler with a relatively high glass to rubber transition temperature (T-g), and from polymer systems with increased thermal conductivity, are evaluated. The mechanical properties of the various filler materials were obtained via ultrasonic measurements, with the thermal properties extracted using dynamic mechanical thermal analysis (dmta), differential scanning calorimetry (dsc) and laserflash studies. A range of ultrasonic transducers were then constructed and their thermal stability studied using a combination of impedance analysis and laser surface displacement measurement

The influence of backward wave transmission on quantitive ultrasonic evaluation using Lamb wave propagation

In view of the various novel quantitative ultrasonic evaluation techniques developed using Lamb wave propagation, the influence of an important related phenomenon, backward transmission, is investigated in this paper. Using the discrete layer theory and a multiple integral transform method, the surface displacement and velocity responses of isotropic plates and cross-ply laminated composite plates due to the Lamb waves excited by parabolic- and piston-type transmitting transducers are evaluated. Analytical expressions for the surface displacement and velocity frequency response functions are developed. Based on this a large volume of calculations is carried out. Through examining the characteristics of the surface displacement and velocity frequency response functions and, especially, the different propagation modes’ contributions to them, the influence of the backward wave transmission related to quantitative ultrasonicnondestructive evaluation applications is discussed and some important conclusions are drawn

Buried shallow fault slip from the South Napa earthquake revealed by near-field geodesy.

Earthquake-related fault slip in the upper hundreds of meters of Earths surface has remained largely unstudied because of challenges measuring deformation in the near field of a fault rupture. We analyze centimeter-scale accuracy mobile laser scanning (MLS) data of deformed vine rows within ±300 m of the principal surface expression of the M (magnitude) 6.0 2014 South Napa earthquake. Rather than assuming surface displacement equivalence to fault slip, we invert the near-field data with a model that allows for, but does not require, the fault to be buried below the surface. The inversion maps the position on a preexisting fault plane of a slip front that terminates ~3 to 25 m below the surface coseismically and within a few hours postseismically. The lack of surface-breaching fault slip is verified by two trenches. We estimate near-surface slip ranging from ~0.5 to 1.25 m. Surface displacement can underestimate fault slip by as much as 30%. This implies that similar biases could be present in short-term geologic slip rates used in seismic hazard analyses. Along strike and downdip, we find deficits in slip: The along-strike deficit is erased after ~1 month by afterslip. We find no evidence of off-fault deformation and conclude that the downdip shallow slip deficit for this event is likely an artifact. As near-field geodetic data rapidly proliferate and will become commonplace, we suggest that analyses of near-surface fault rupture should also use more sophisticated mechanical models and subsurface geomechanical tests