Investigation of displacement fields in an abrasive waterjet drilling process: Part 1. Experimental measurements

2001 ◽  
Vol 41 (4) ◽  
pp. 375-387 ◽  
Author(s):  
Z. Guo ◽  
M. Ramulu
Keyword(s):  
Abrasive Waterjet ◽  
Experimental Measurements ◽  
Drilling Process ◽  
Displacement Fields ◽  
Abrasive Waterjet Drilling

Strain and Stress Analysis around the Notches Using ESPI Method

2014 ◽  
Vol 611 ◽  
pp. 484-489
Author(s):  
Matúš Kalina ◽  
František Šimčák
Keyword(s):  
Stress Analysis ◽  
Shear Loading ◽  
Optical Methods ◽  
Stress Fields ◽  
Experimental Measurements ◽  
Coherent Light ◽  
Displacement Fields

Modern speckle optical methods use the properties of coherent light for identification of displacement fields. One of these methods is method ESPI. Using of this method strain and stress fields on surface of flat test samples with symmetric notches by tensile and shear loading were identified. A special fixture for shear loading of test samples was designed. The shape and dimensions of the fixture were modified on the basic results of experimental measurements. A modification allowed us to obtain a better analyse of strain and stress fields of test samples with symmetric V notches.

scholarly journals Sensitivity Studies and Parameters Identification for Noisy 3D Moving AWJM Model

2016 ◽  
Vol 2016 ◽  
pp. 1-15
Author(s):  
Didier Auroux ◽  
Vladimir Groza
Keyword(s):  
Measurement Errors ◽  
Automatic Differentiation ◽  
Abrasive Waterjet ◽  
Model Parameters ◽  
Experimental Measurements ◽  
Feed Speed ◽  
Optimal Model ◽  
Different Types ◽  
Sensitivity Studies ◽  
Adjoint Approach

This work focuses on the identification of optimal model parameters related to Abrasive Waterjet Milling (AWJM) process. The evenly movement as well as variations of the jet feed speed was taken into account and studied in terms of 3D time dependent AWJM model. This gives us the opportunity to predict the shape of the milled trench surfaces. The required trench profile could be obtained with high precision in lack of knowledge about the model parameters and based only on the experimental measurements. We use the adjoint approach to identify the AWJM model parameters. The complexity of inverse problem paired with significant amount of unknowns makes it reasonable to use automatic differentiation software to obtain the adjoint statement. The interest in investigating this problem is caused by needs of industrial milling applications to predict the behavior of the process. This study proposes the possibility of identifying the AWJM model parameters with sufficiently high accuracy and predicting the shapes formation relying on self-generated data or on experimental measurements for both evenly jets movement and arbitrary changes of feed speed. We provide the results acceptable in the production and estimate the suitable parameters taking into account different types of model and measurement errors.

scholarly journals Experimental study on the hole quality during abrasive waterjet drilling of CFRP

2021 ◽  
Vol 13 (2) ◽  
pp. 103-108
Author(s):  
Panagiotis Karmiris-Obratański ◽  
◽  
Nikolaos E. Karkalos ◽  
Dimitrios Skondras-Giousios ◽  
Emmanouil-Lazaros Papazoglou ◽  
...  
Keyword(s):  
Design Method ◽  
Orthogonal Design ◽  
Optical Microscope ◽  
Hole Diameter ◽  
Standoff Distance ◽  
Abrasive Waterjet ◽  
Hole Quality ◽  
Machining Processes ◽  
The Impact ◽  
Abrasive Waterjet Drilling

Abrasive Waterjet (AWJ) machining is considered an excellent alternative to conventional machining processes due to its superb machining characteristics. More specifically, Abrasive Waterjet drilling is nowadays a promising non-conventional process for obtaining high quality holes. In the present study, drilling experiments based on Taguchi L9 orthogonal design method were conducted via AWJ on carbon fiber reinforced polymer (CFRP) plate at various waterjet parameters, namely, different pressure, abrasive mass flow rate and standoff distance values. The purpose of the experiments was to investigate the impact of these process parameters on the quality of holes. The hole quality was determined by measuring the hole diameter error as well as the hole taper. The optical evaluation was implemented with the use of optical microscope and special measuring software. The ANOVA analysis of the results showed a significant influence of standoff distance regarding the hole diameter error and a combined influence of waterjet pressure and standoff distance regarding the hole taper. Furthermore, the optimal process parameter values for the optimization of the hole diameter error and hole taper were determined. The hole quality in terms of defects appearance was also quantitatively inspected, through optical imaging.

Simulation and Contrast Analysis of tem Images of Cracks

1990 ◽  
Vol 48 (1) ◽  
pp. 578-579
Author(s):  
D. Goyal ◽  
A. H. King
Keyword(s):  
Displacement Vector ◽  
Crack Tip ◽  
Perfect Crystal ◽  
Operating Conditions ◽  
Displacement Fields ◽  
Fringe Contrast ◽  
Orthogonal Geometry ◽  
Moire Fringe ◽  
Moiré Fringe

TEM images of cracks have been found to give rise to a moiré fringe type of contrast. It is apparent that the moire fringe contrast is observed because of the presence of a fault in a perfect crystal, and is characteristic of the fault geometry and the diffracting conditions in the TEM. Various studies have reported that the moire fringe contrast observed due to the presence of a crack in an otherwise perfect crystal is distinctive of the mode of crack. This paper describes a technique to study the geometry and mode of the cracks by comparing the images they produce in the TEM because of the effect that their displacement fields have on the diffraction of electrons by the crystal (containing a crack) with the corresponding theoretical images. In order to formulate a means of matching experimental images with theoretical ones, displacement fields of dislocations present (if any) in the vicinity of the crack are not considered, only the effect of the displacement field of the crack is considered.The theoretical images are obtained using a computer program based on the two beam approximation of the dynamical theory of diffraction contrast for an imperfect crystal. The procedures for the determination of the various parameters involved in these computations have been well documented. There are three basic modes of crack. Preliminary studies were carried out considering the simplest form of crack geometries, i. e., mode I, II, III and the mixed modes, with orthogonal crack geometries. It was found that the contrast obtained from each mode is very distinct. The effect of variation of operating conditions such as diffracting vector (), the deviation parameter (ω), the electron beam direction () and the displacement vector were studied. It has been found that any small change in the above parameters can result in a drastic change in the contrast. The most important parameter for the matching of the theoretical and the experimental images was found to be the determination of the geometry of the crack under consideration. In order to be able to simulate the crack image shown in Figure 1, the crack geometry was modified from a orthogonal geometry to one with a crack tip inclined to the original crack front. The variation in the crack tip direction resulted in the variation of the displacement vector also. Figure 1 is a cross-sectional micrograph of a silicon wafer with a chromium film on top, showing a crack in the silicon.

Sign in / Sign up

Export Citation Format

Share Document