An investigation of photoresists for use in optical strain analysis

1970 ◽  
Vol 5 (3) ◽  
pp. 162-168 ◽  
Author(s):  
A Luxmoore ◽  
R Hermann
Keyword(s):  
Strain Measurement ◽  
Strain Analysis ◽  
Surface Strain ◽  
High Contrast ◽  
Moire Method ◽  
Optical Strain

Some commercial photoresists have been examined to assess their suitability for use with the moiré method of surface-strain measurement. As most of these materials do not produce a pattern of high contrast directly, some etching and plating procedures are also described. Combined with correct illumination, these processes will produce grids of sufficient contrast for most applications.

General interpretation of moiré patterns in strain analysis

1968 ◽  
Vol 3 (2) ◽  
pp. 90-95 ◽  
Author(s):  
B Košťáuk
Keyword(s):  
Physical Meaning ◽  
Strain Measurement ◽  
Strain Analysis ◽  
Theoretical Treatment ◽  
Two Dimensional ◽  
Contour Lines ◽  
Moire Patterns ◽  
Moire Method ◽  
System Properties ◽  
Moiré Patterns

A simple theoretical treatment of moiré patterns is given with the use of relations between diagonal systems that have the physical meaning of contour lines of the functions in question. The general approach and knowledge of diagonal-system properties can simplify various problems of strain measurement by the moiré method, and this is demonstrated by the compensation of a moiré pattern and by the method of two-dimensional strain measurement.

A Methodology for Real Time Surface Strain Measurement for Stamping Through Non-Contact Optical Strain Measurement System

2007 ◽  
Vol 344 ◽  
pp. 855-861 ◽  
Author(s):  
Shankar Kalyanasundaram ◽  
Paul Compston ◽  
Joel Gresham
Keyword(s):  
Strain Measurement ◽  
Surface Strain ◽  
Failure Behavior ◽  
Element Analysis ◽  
Strain Evolution ◽  
Numerical Studies ◽  
Optical Strain Measurement ◽  
Photogrammetric Method ◽  
Optical Strain

The quality of stamp formed parts depends on a number of variables. Numerical studies based on finite element analysis can provide evolution of strain during forming and correlate with different failures of the formed parts. This study presents a methodology of capturing the evolution of strain during forming through a photogrammetric method. An open die was used to monitor the strain evolution of domed parts. The forming characteristic of a fibre-metal laminate system was compared to a monolithic aluminum alloy to elucidate the differences in the strain evolution during forming. It was found that the two materials exhibited different strain evolution during forming and this affected the failure behavior of the formed parts.

CGA: An image processing based software for surface strain analysis in sheet metal forming

2021 ◽  
pp. 030932472199657
Author(s):  
Wankhede Pankaj ◽  
Tejas Radhakrishnan ◽  
Kurra Suresh ◽  
Sudha Radhika
Keyword(s):  
Image Processing ◽  
Sheet Metal ◽  
Measurement System ◽  
Sheet Metal Forming ◽  
Metal Forming ◽  
Strain Measurement ◽  
Strain Analysis ◽  
Surface Strain ◽  
Percentage Error ◽  
Flat Sheet

Strain analysis is an essential step in sheet forming applications to understand the deformation behaviour of the material. The strain analysis is conventionally performed by Circle Grid Analysis (CGA). In CGA, a grid of circles with 2 mm–5 mm diameter is printed on a flat sheet and deformed into the required shape. The length of major and minor axes of the deformed ellipses are measured to estimate the strains at different locations of the formed component. The major and minor axes length of the deformed ellipses are measured either by using a manual method or automatic methods. The automated methods are faster and accurate compared to manual methods, but to perform strain measurement using commercially available automatic strain measurement system, is very expensive. Therefore, in this paper, an image processing based software has been developed with user-friendly Graphical User Interface (GUI) for strain measurement and analysis in sheet metal forming operations. The software has been tested on images obtained by printing the ellipses of known dimensions on the flat sheet by laser etching, electrochemical etching and screen printing, which are generally used for printing circular grids on flat sheets for strain analysis in sheet metal forming. It is observed that the edges of the laser engraved ellipse are very slim and easily detected by software compared to other grid printing methods. The developed software can measure the ellipse dimensions with a maximum absolute percentage error of 1.975%. Further, the results of CGA software has been compared with the commercial strain measurement system called Grid Pattern Analyzer (GPA). The mean absolute error in strain measurement using CGA and GPA was found to be 0.0106 and 0.0178, respectively. The statistical test results reveal that there is no evidence to support a claim that there is a difference in mean performance between the two methods.

Monitoring High Temperature Steam Pipes Using Optical Strain Measurement Techniques

2006 ◽  
Vol 5-6 ◽  
pp. 145-152 ◽  
Author(s):  
Andrew Morris ◽  
John P. Dear ◽  
Miltiadis Kourmpetis
Keyword(s):  
Wind Turbine ◽  
Strain Measurement ◽  
Measurement Techniques ◽  
Turbine Blades ◽  
Monitoring Methods ◽  
Wind Turbine Blades ◽  
Optical Strain Measurement ◽  
Optical Strain ◽  
High Temperature Steam ◽  
Steam Pipes

Optical strain measurement techniques have been extensively developed in recent years in order to cope in various environments. Power stations and wind turbine blades can provide challenging environments for the use of a measurement technique. There are, however, many installation problems to be overcome. For example, there is the need to have regard for the hostile environment in steam generating plant and the demanding conditions to which wind turbine blades are subjected. Ideally the outputs from individual sensors would be used for continuous remote monitoring. However, measurements can also be useful each time the plant is shut down during a plant outage; which would be used to complement data from existing proven rugged monitoring methods. This paper addresses the monitoring of pressurized steam pipes as to their micro-strain growth related to time in service. This paper presents the progress made in the developing of a ruggedised digital speckle ‘sensor’ and associated image capture system. The effect of subsurface defects in the strain distribution is examined.

Comparative Study of As-Built Geometric and Mechanical Properties of Additively Manufactured Ceramics

2018 ◽  
Author(s):  
John C. Steuben ◽  
Athanasios P. Iliopoulos ◽  
John G. Michopoulos
Keyword(s):  
Mechanical Properties ◽  
Strain Measurement ◽  
High Performance ◽  
Marked Decrease ◽  
Measurement Techniques ◽  
Direct Ink Writing ◽  
Optical Strain Measurement ◽  
Broad Variety ◽  
Optical Strain ◽  
Am Processes

Additive Manufacturing (AM) encompasses a broad variety of fabrication techniques characterized by successive additions of mass and/or energy to a build domain. AM processes have been developed for a wide variety of feedstock materials, including metals, polymers, and ceramics. In the present work we study the AM of ceramics using the Direct Ink Writing (DIW) technique. We performed comparative studies between additively manufactured and conventionally manufactured test articles, in order to quantify the variations in output geometry and mechanical properties induced by the DIW process. Uniaxial tests are conducted using high-performance optical strain measurement techniques. In particular, it is shown that the DIW-produced specimens exhibit anisotropic shrinkage when fired, as well as a marked decrease in stiffness and ultimate strength. We conclude with a discussion of potential mechanisms which may be responsible for these property degradations, and introduce potential adaptations to the DIW AM process that may be effective in combating them.

Advanced measurement techniques for braided composite structures: A review of current and upcoming trends

2020 ◽  
Vol 54 (25) ◽  
pp. 3895-3917 ◽  
Author(s):  
Garrett W Melenka ◽  
Cagri Ayranci
Keyword(s):  
Computed Tomography ◽  
Strain Measurement ◽  
Composite Structures ◽  
Measurement Methods ◽  
Micro Computed Tomography ◽  
Braided Composites ◽  
Optical Strain Measurement ◽  
In Situ Strain Measurement ◽  
Optical Strain

Braiding is an advanced textile manufacturing method that is used to produce two-dimensional and three-dimensional components. Unlike laminated structures, braids have interlaced yarns that form a continuity between layers. This structure allows for improved impact resistance, damage tolerance, and improved through-thickness reinforcement. Despite the numerous advantages of braided composites, braids also have shortcomings. Their highly complex fiber architecture presents challenges in the availability and choice of the strain measuring and characterization techniques. Advanced measurement methods such as optical strain measurement, micro-computed tomography, and in situ strain measurement are required. Optical strain measurement methods such as digital image correlation and high-speed imaging are necessary to accurately measure the complex deformation and failure that braided composites exhibit. X-ray-based micro-computed tomography measurements can provide detailed geometric and morphologic information for braided structures, which is necessary for accurately predicting the mechanical properties of braided structures. Finally, in situ strain measurement methods will provide detailed information on the internal deformation and strain that exists within braided structures. In situ sensors will also allow for in-service health monitoring of braided structures. This paper provides a detailed review of the aforementioned sensing technologies and their relation to the measurement of braided composite structures.

Optical strain measurement in ultrathin sSOI wafer

2006 ◽  
Vol 253 (1-2) ◽  
pp. 18-21 ◽  
Author(s):  
J. Munguía ◽  
H. Chouaib ◽  
J. de la Torre ◽  
G. Bremond ◽  
C. Bru-Chevallier ◽  
...  
Keyword(s):  
Strain Measurement ◽  
Optical Strain Measurement ◽  
Optical Strain
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