A Strategy for Generating Contoured Surface With Abrasive Waterjet Milling on Ductile Materials

2012 ◽  
Author(s):  
R. Srikanth ◽  
N. Ramesh Babu
Keyword(s):  
Control Strategy ◽  
Control Strategies ◽  
Dimensional Accuracy ◽  
Impact Angle ◽  
Surface Generation ◽  
Abrasive Waterjet ◽  
Ductile Materials ◽  
Stainless Steel 304 ◽  
Waterjet Machining ◽  
Milled Surface

Surface generation by abrasive waterjet milling is one of the emerging applications of waterjet machining for processing of difficult to cut materials like super alloys, titanium alloys and hardened tool steels. The key aspect lies in the identification of certain important parameters that influence the kerf geometry and develop control strategies to produce easily reproducible kerfs and combine them together to produce a contoured surface. In this work, an attempt is made to devise control strategies, based on certain kinematic operating parameters like traverse rate, stand-off distance and impact angle of jet on the material, to generate a series of reproducible kerfs and to merge them together to produce a contoured surface. This is achieved by first discretely milling the surface into a series of kerfs separated by thin unmachined region and then gradually increasing the depth of these kerfs to match the requirements of the contoured surface with multiple traversal of jet. Subsequently these kerfs are merged by removing the regions separating them. The proposed control strategy is demonstrated by milling contoured surface on stainless steel 304 alloy. Finally, the efficiency of the proposed control strategy for producing contoured surface is assessed in terms of dimensional accuracy achieved on the milled surface.

Mathematical Modeling of Abrasive Waterjet Turning of Ductile Materials

2010 ◽  
Author(s):  
Iman Zohourkari ◽  
Mehdi Zohoor
Keyword(s):  
Abrasive Particle ◽  
Experimental Tests ◽  
Traverse Speed ◽  
Impact Angle ◽  
Abrasive Waterjet ◽  
Continuous Change ◽  
Turning Process ◽  
Ductile Materials ◽  
Proposed Model ◽  
Cylindrical Workpiece

In this paper, an erosion-based model for abrasive waterjet (AWJ) turning process is presented. In the AWJ turning process a particular volume of material is removed by impacting of abrasive particles to the surface of the rotating cylindrical workpiece. This volume is estimated according to the modified Hashish erosion model; thus radius reduction at each revolution is calculated. The distinctively proposed model considers the continuous change in local impact angle due to change in workpiece diameter, axial traverse speed of the jet, the abrasive particle roundness and density. The accuracy of the proposed model is approved by experimental tests under various traverse speeds. The final diameters estimated by the new model are in good accordance with the experiments.

The Effect of Beam Angle in Abrasive-Waterjet Machining

1993 ◽  
Vol 115 (1) ◽  
pp. 51-56 ◽  
Author(s):  
M. Hashish
Keyword(s):  
Removal Rate ◽  
Rake Angle ◽  
Impact Angle ◽  
Abrasive Waterjet ◽  
Depth Of Cut ◽  
Abrasive Waterjet Machining ◽  
Coated Materials ◽  
Waterjet Machining ◽  
Abrasive Waterjets ◽  
The Impact

In the machining of materials, abrasive-waterjets are typically applied at a 90 deg. angle to the surface of the workpiece. This paper presents results and observations on machining with abrasive-waterjets at angles other than 90 deg. Previous visualization studies of the cutting process in transparent materials have shown that there are optimal angles for maximum depth of cut and kerf depth uniformity. Here, observations on the effect of angle in machining applications such as turning, milling, linear cutting, and drilling are addressed. The effects of variations in both the impact angle and the rake angle are investigated. Results indicate that the volume removal rate is significantly affected by these angles and that the surface finish can be improved by angling the jet. However, shallow angle drilling of small holes in laminated or ceramic-coated materials requires further investigation.

scholarly journals Evaluation of a home-based 7-day infection control strategy for healthcare workers following high-risk exposure to severe acute respiratory coronavirus virus 2 (SARS-CoV-2): A cohort study

2020 ◽  
pp. 1-4
Author(s):  
Carla Benea ◽  
Laura Rendon ◽  
Jesse Papenburg ◽  
Charles Frenette ◽  
Ahmed Imacoudene ◽  
...  
Keyword(s):  
High Risk ◽  
Infection Control ◽  
Control Strategy ◽  
Healthcare Workers ◽  
Control Strategies ◽  
Risk Exposure ◽  
Nasopharyngeal Swab ◽  
Home Based ◽  
Respiratory Coronavirus ◽  
Second Wave

Abstract Objective: Evidence-based infection control strategies are needed for healthcare workers (HCWs) following high-risk exposure to severe acute respiratory coronavirus virus 2 (SARS-CoV-2). In this study, we evaluated the negative predictive value (NPV) of a home-based 7-day infection control strategy. Methods: HCWs advised by their infection control or occupational health officer to self-isolate due to a high-risk SARS-CoV-2 exposure were enrolled between May and October 2020. The strategy consisted of symptom-triggered nasopharyngeal SARS-CoV-2 RNA testing from day 0 to day 7 after exposure and standardized home-based nasopharyngeal swab and saliva testing on day 7. The NPV of this strategy was calculated for (1) clinical coronavirus disease 2019 (COVID-19) diagnosis from day 8–14 after exposure, and for (2) asymptomatic SARS-CoV-2 detected by standardized nasopharyngeal swab and saliva specimens collected at days 9, 10, and 14 after exposure. Interim results are reported in the context of a second wave threatening this essential workforce. Results: Among 30 HCWs enrolled, the mean age was 31 years (SD, ±9), and 24 (80%) were female. Moreover, 3 were diagnosed with COVID-19 by day 14 after exposure (secondary attack rate, 10.0%), and all cases were detected using the 7-day infection control strategy: the NPV for subsequent clinical COVID-19 or asymptomatic SARS-CoV-2 detection by day 14 was 100.0% (95% CI, 93.1%–100.0%). Conclusions: Among HCWs with high-risk exposure to SARS-CoV-2, a home-based 7-day infection control strategy may have a high NPV for subsequent COVID-19 and asymptomatic SARS-CoV-2 detection. Ongoing data collection and data sharing are needed to improve the precision of the estimated NPV, and here we report interim results to inform infection control strategies in light of a second wave threatening this essential workforce.

scholarly journals Impacts of Traverse Speed and Material Thickness on Abrasive Waterjet Contour Cutting of Austenitic Stainless Steel AISI 304L

2021 ◽  
Vol 11 (11) ◽  
pp. 4925
Author(s):  
Jennifer Milaor Llanto ◽  
Majid Tolouei-Rad ◽  
Ana Vafadar ◽  
Muhammad Aamir
Keyword(s):  
Material Removal Rate ◽  
Material Removal ◽  
Removal Rate ◽  
Traverse Speed ◽  
Abrasive Waterjet ◽  
Taper Angle ◽  
Material Thickness ◽  
Abrasive Waterjet Machining ◽  
Kerf Taper ◽  
Waterjet Machining

Abrasive water jet machining is a proficient alternative for cutting difficult-to-machine materials with complex geometries, such as austenitic stainless steel 304L (AISI304L). However, due to differences in machining responses for varied material conditions, the abrasive waterjet machining experiences challenges including kerf geometric inaccuracy and low material removal rate. In this study, an abrasive waterjet machining is employed to perform contour cutting of different profiles to investigate the impacts of traverse speed and material thickness in achieving lower kerf taper angle and higher material removal rate. Based on experimental investigation, a trend of decreasing the level of traverse speed and material thickness that results in minimum kerf taper angle values of 0.825° for machining curvature profile and 0.916° for line profiles has been observed. In addition, higher traverse speed and material thickness achieved higher material removal rate in cutting different curvature radii and lengths in line profiles with obtained values of 769.50 mm3/min and 751.5 mm3/min, accordingly. The analysis of variance revealed that material thickness had a significant impact on kerf taper angle and material removal rate, contributing within the range of 69–91% and 62–69%, respectively. In contrast, traverse speed was the least factor measuring within the range of 5–18% for kerf taper angle and 27–36% for material removal rate.

Application of Combined Feedforward and Feedback Controller With Shaped Input to Benchmark Problem

2010 ◽  
Vol 132 (2) ◽  
Author(s):  
Young Joo Shin ◽  
Peter H. Meckl
Keyword(s):  
Feedback Control ◽  
Control Strategy ◽  
Control Strategies ◽  
Control Design ◽  
Single Frequency ◽  
Benchmark Problems ◽  
Control Force ◽  
Benchmark Problem ◽  
Advantages And Disadvantages ◽  
Robust Control Design

Benchmark problems have been used to evaluate the performance of a variety of robust control design methodologies by many control engineers over the past 2 decades. A benchmark is a simple but meaningful problem to highlight the advantages and disadvantages of different control strategies. This paper verifies the performance of a new control strategy, which is called combined feedforward and feedback control with shaped input (CFFS), through a benchmark problem applied to a two-mass-spring system. CFFS, which consists of feedback and feedforward controllers and shaped input, can achieve high performance with a simple controller design. This control strategy has several unique characteristics. First, the shaped input is designed to extract energy from the flexible modes, which means that a simpler feedback control design based on a rigid-body model can be used. In addition, only a single frequency must be attenuated to reduce residual vibration of both masses. Second, only the dynamics between control force and the first mass need to be considered in designing both feedback and feedforward controllers. The proposed control strategy is applied to a benchmark problem and its performance is compared with that obtained using two alternative control strategies.

Abrasive Waterjet Cutting of Aluminum Alloys: Workpiece Surface Roughness

2013 ◽  
Vol 404 ◽  
pp. 3-9 ◽  
Author(s):  
Nihat Tosun ◽  
Ihsan Dagtekin ◽  
Latif Ozler ◽  
Ahmet Deniz
Keyword(s):  
Mechanical Properties ◽  
Surface Roughness ◽  
Aluminum Alloys ◽  
Abrasive Waterjet ◽  
Traditional Methods ◽  
Workpiece Surface ◽  
Abrasive Waterjet Machining ◽  
Waterjet Machining ◽  
Area Of Application ◽  
Better Than

Abrasive waterjet machining is one of the non-traditional methods of the recent years which found itself a wide area of application in the industry for machining of different materials. In this paper, the surface roughness of 6061-T6 and 7075-T6 aluminum alloys are being cut with abrasive waterjet is examined experimentally. The experiments were conducted with different waterjet pressures and traverse speeds. It has been found that the surface roughness obtained by cutting material with high mechanical properties is better than that of obtained by cutting material with inferior mechanical properties.

Robust H2/H∞Control Strategy for Linear Markovian Jump Systems

2014 ◽  
Vol 525 ◽  
pp. 646-652
Author(s):  
Min Bian ◽  
Qing Yun Guo
Keyword(s):  
Control Strategy ◽  
State Feedback ◽  
Control Strategies ◽  
State Feedback Control ◽  
Linear Matrix ◽  
Bounded Real Lemma ◽  
Finite State ◽  
Linear State ◽  
Feasible Solutions ◽  
Jump Systems

The robust H2/<em>H</em>∞ control strategy for a class of linear continuous-time uncertain systems with randomly jumping parameters is investigated. The transition of the jumping parameters is decided by a finite-state Markov process. The uncertainties are supposed to be norm-bounded. It is desired to design a linear state feedback control strategies such that the closed-loop system satisfies H performance and minimizes the H2 norm of the system. A sufficient condition is first established on the existence of the robust H2/<em>H</em>∞controller bases on the bounded real lemma. Then the corresponding state-feedback law is given in terms of a set of linear matrix inequalities (LMIs). It is showed that this condition is equivalent to the feasible solutions problem of LMI. Furthermore, the control strategy design problem is converted into a convex optimization problem subject to LMI constraints, which can be easily solved by standard numerical software.

Effect of abrasive waterjet machining on LaPO4/Y2O3 ceramic matrix composite

2017 ◽  
Vol 54 (2) ◽  
pp. 205-214 ◽  
Author(s):  
K. Balamurugan ◽  
M. Uthayakumar ◽  
S. Sankar ◽  
U. S. Hareesh ◽  
K. G. K. Warrier
Keyword(s):  
Matrix Composite ◽  
Ceramic Matrix Composite ◽  
Ceramic Matrix ◽  
Abrasive Waterjet ◽  
Abrasive Waterjet Machining ◽  
Waterjet Machining
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