Mathematical Modeling of Ultra-High-Pressure Waterjet Peening

2005 ◽  
Vol 127 (2) ◽  
pp. 186-191 ◽  
Author(s):  
S. Kunaporn ◽  
M. Ramulu ◽  
M. Hashish
Keyword(s):  
Mathematical Modeling ◽  
High Pressure ◽  
High Cycle Fatigue ◽  
Fatigue Tests ◽  
Analytical Models ◽  
Test Results ◽  
Ultra High Pressure ◽  
Proposed Model ◽  
Compressive Residual Stresses ◽  
Good Agreement

Waterjet peening is a recent promising method in surface treatment. It has the potential to induce compressive residual stresses that benefit the fatigue life of materials similar to the conventional shot peening process. However, there are no analytical models that incorporate process parameters (i.e., supply pressure, jet exposure time, and nozzle traverse rate, etc) to allow predicting the optimized peening process. Mathematical modeling of high-pressure waterjet peening was developed in this study to describe the relation between the waterjet peening parameters and the resulting material modifications. Results showed the possibility of using the proposed mathematical model to predict an initial range for effective waterjet peening under the variation of waterjet peening conditions. The high cycle fatigue tests were performed to validate the proposed model and fatigue test results showed good agreement with the predictions.

High-cycle fatigue tests of pretensioned concrete beams

PCI Journal ◽  
2022 ◽  
Vol 67 (1) ◽  
Author(s):  
Jörn Remitz ◽  
Martin Empelmann
Keyword(s):  
Fatigue Life ◽  
High Cycle Fatigue ◽  
Concrete Beams ◽  
Fatigue Behavior ◽  
Fatigue Tests ◽  
Design Methods ◽  
Test Results ◽  
Cycle Fatigue ◽  
Pretensioned Concrete ◽  
Current Design

Pretensioned concrete beams are widely used as bridge girders for simply supported bridges. Understanding the fatigue behavior of such beams is very important for design and construction to prevent fatigue failure. The fatigue behavior of pretensioned concrete beams is mainly influenced by the fatigue of the prestressing strands. The evaluation of previous test results from the literature indicated a reduced fatigue life in the long-life region compared with current design methods and specifications. Therefore, nine additional high-cycle fatigue tests were conducted on pretensioned concrete beams with strand stress ranges of about 100 MPa (14.5 ksi). The test results confirmed that current design methods and specifications overestimate the fatigue life of embedded strands in pretensioned concrete beams.

Plastic Effects on High Cycle Fatigue at the Edge of Contact of Turbine Blade Fixtures

2017 ◽  
Vol 140 (4) ◽  
Author(s):  
C. H. Richter ◽  
U. Krupp ◽  
M. Zeißig ◽  
G. Telljohann
Keyword(s):  
Finite Element Analysis ◽  
High Cycle Fatigue ◽  
Turbine Blades ◽  
Fatigue Tests ◽  
Cycle Fatigue ◽  
Element Analysis ◽  
Notched Specimens ◽  
The Finite Element Analysis ◽  
Slip Region ◽  
Good Agreement

Slender turbine blades are susceptible to excitation. Resulting vibrations stress the blade's fixture to the rotor or stator. In this paper, high cycle fatigue at the edge of contact (EOC) between blade and rotor/stator of such fixtures is investigated both experimentally and numerically. Plasticity in the contact zone and its effects on, e.g., contact tractions, fatigue determinative quantities, and fatigue itself are shown to be of considerable relevance. The accuracy of the finite element analysis (FEA) is demonstrated by comparing the predicted utilizations and slip region widths with data gained from tests. For the evaluation of EOC fatigue, tests on simple notched specimens provide the limit data. Predictions on the utilization are made for the EOC of a dovetail setup. Tests with this setup provide the experimental fatigue limit to be compared to. The comparisons carried out show a good agreement between the experimental results and the plasticity-based calculations of the demonstrated approach.

Waterjet Peening and Surface Preparation at 600MPa: A Preliminary Experimental Study

2006 ◽  
Vol 129 (4) ◽  
pp. 485-490 ◽  
Author(s):  
A. Chillman ◽  
M. Ramulu ◽  
M. Hashish
Keyword(s):  
Experimental Study ◽  
Plastic Deformation ◽  
High Pressure ◽  
Subsurface Layer ◽  
Surface Preparation ◽  
Material Surface ◽  
Ultra High Pressure ◽  
Shock Peening ◽  
Droplet Impacts ◽  
Compressive Residual Stresses

An experimental study was conducted to explore the surface preparation as well as the effects of high-pressure waterjet peening at 600MPa on the surface integrity and finish of metals. The concept of larger droplet size and multiple droplet impacts resulting from an ultra-high-pressure waterjet was used to explore and develop the peening process. A combination of microstructure analysis, microhardness measurements, and profilometry were used in determining the depth of plastic deformation and surface finish that result from the surface treatment process. It was found that waterjet peening at 600MPa induces plastic deformation to greater depths in the subsurface layer of metals than laser shock peening. The degree of plastic deformation and the state of the material surface were found to be strongly dependent on the peening conditions and desired surface roughness. Based on these first investigation results, water peening at 600MPa may serve as a new method for introducing compressive residual stresses in engineering components.

Waterjet Peening At 600MPa: A First Investigation

2005 ◽  
Author(s):  
M. Hashsish ◽  
A. Chillman ◽  
M. Ramulu
Keyword(s):  
Plastic Deformation ◽  
High Pressure ◽  
Treatment Process ◽  
Laser Shock Peening ◽  
Material Surface ◽  
Laser Shock ◽  
Ultra High Pressure ◽  
Shock Peening ◽  
Droplet Impacts ◽  
Compressive Residual Stresses

An experimental study was conducted to explore the high-pressure waterjet (WJ) peening at 600MPa on the surface integrity and texture of metals. The concept of larger droplet size and multiple droplet impacts resulting from an ultra high-pressure waterjet (UHPWJ) was used to explore and develop the peening process. A combination of microstructure analysis, microhardness measurements, and profilometry were used in determining the depth of plastic deformation and surface texture that result from the surface treatment process. It was found that waterjet peening at 600MPa induces plastic deformation to greater depths in the sub-surface layer of metals than laser shock peening. The degree of plastic deformation and the state of material surface were found to be strongly dependent on the peening conditions and desired surface roughness. Based on these first investigation results, water peening at 600MPa may serve as a new method for introducing compressive residual stresses in engineering components.

Predicting the Strength of Rectangular Reinforced Concrete Columns Confined with FRP Sheets

2022 ◽  
Vol 906 ◽  
pp. 17-23
Author(s):  
Ashot G. Tamrazyan ◽  
Yehia A.K. Sayed
Keyword(s):  
Compressive Strength ◽  
Regression Analysis ◽  
Concrete Columns ◽  
Test Results ◽  
Rc Columns ◽  
New Model ◽  
Proposed Model ◽  
Axial Compressive Strength ◽  
Frp Sheet ◽  
Good Agreement

A complete reorganization about the behavior of rectangular RC columns confined with FRP sheet is very important to predict the axial compressive strength values of the strengthened rectangular RC columns. That is because the process of strengthening RC rectangular column depending on several parameters that role this type of strengthening. These parameters include the characteristics of the used fiber, the grade of concrete and the geometry of the cross section including the rectangularity aspect ratio, corner radius, and size of specimens. Besides that, using a wide scope of experimental data may affect positively to generalize a model that considers the whole parameters affect the value of the axial strength. So, in this paper a review about parameters that affect the axial compressive strength values of rectangular RC columns was conducted. After that, based on the test results regarding FRP-confined rectangular RC columns available in the literature or conducted by the author, some existing confinement models for rectangular RC columns were assessed. Further, a new model is proposed through regression analysis of the database. A new model is proposed through regression analysis of the database. The proposed model was found to be in good agreement with the test results in the database. Finally, based on the results conclusions were drawn.

One-Dimensional Nonlinear Parametric Instability of Inhomogeneous Plasma: Time Domain Problem

2021 ◽  
Vol 24 (3) ◽  
pp. 272-279
Author(s):  
N. V. Gerasimenko ◽  
F. M. Trukhachev ◽  
E. Z. Gusakov ◽  
L. V. Simonchik ◽  
A. V. Tomov
Keyword(s):  
Initial Conditions ◽  
Inhomogeneous Plasma ◽  
Parametric Instability ◽  
Analytical Models ◽  
Dimensional Model ◽  
One Dimensional ◽  
Proposed Model ◽  
Wide Range ◽  
Spatial And Temporal Characteristics ◽  
Good Agreement

A numerical one-dimensional model of convective parametric instability of inhomogeneous plasma is developed. By using this model, a numerical solution describing spatial and temporal characteristics of interacting waves is obtained. The results obtained are in a good agreement with known analytical models and substantially generalize them. In particular, an important advantage of the proposed model is the possibility of varying initial conditions, analyzing behavior of the system in the presence of incident wave fluctuations that is important for the future study of the absolute instability mode. The model is also provides possibility to simulate absolute parametric instability with a wide range of controllable parameters, as well as to study interacting wave transients.

Model for predicting displacement-dependent lateral earth pressure

2009 ◽  
Vol 46 (8) ◽  
pp. 969-975 ◽  
Author(s):  
Guoxiong Mei ◽  
Qiming Chen ◽  
Linhui Song
Keyword(s):  
Earth Pressure ◽  
The State ◽  
Passive State ◽  
Test Results ◽  
Lateral Earth Pressure ◽  
The Earth ◽  
Proposed Model ◽  
Pressure Changes ◽  
The Relationship ◽  
Good Agreement

A model for predicting displacement-dependent lateral earth pressure was proposed based on an earth pressure – displacement relationship commonly observed in practice. The proposed model is a monotonically increasing and bounded function, with an inflection point at the displacement of s = 0 at which the earth pressure changes from the intermediate active state (the state between active and at-rest) to the intermediate passive state (the state between at-rest and passive). The proposed model can predict the relationship between earth pressure and retaining structure movement for any condition intermediate to the active and passive states, which was verified by the experimental data reported in published literature. The predicted lateral earth pressure coefficients are in good agreement with the test results of model tests reported in the literature.

Mathematical modeling and numerical simulation of nonlinearly elastic yarn in ring spinning

2020 ◽  
pp. 004051752094080
Author(s):  
Rong Yin
Keyword(s):  
Mathematical Modeling ◽  
Equations Of Motion ◽  
Second Law ◽  
Ring Spinning ◽  
Linear Elastic ◽  
Proposed Model ◽  
The Finite Difference Method ◽  
Nonlinear Elastic ◽  
Nonlinearly Elastic ◽  
Good Agreement

In this paper, yarn dynamic behavior in the ring spinning system has been studied. A new model has been proposed by considering nonlinear elastic yarn. Equations of motion were derived by Newton’s second law and resolved by the finite difference method. Some results were given and relationships among models of inextensible yarn, linear elastic yarn, and nonlinearly elastic yarn were discussed. Experiments were conducted to evaluate the accuracy of the proposed model in terms of yarn tension and balloon profile and a good agreement has been made between the predicted data and experimental results.

Development and test of a self-centering fluidic viscous damper

2020 ◽  
Vol 23 (13) ◽  
pp. 2835-2849
Author(s):  
Ruizhao Zhu ◽  
Tong Guo ◽  
Frank Mwangilwa
Keyword(s):  
Energy Dissipation ◽  
Numerical Model ◽  
Analytical Model ◽  
Fatigue Tests ◽  
The Self ◽  
Analytical Models ◽  
Viscous Damper ◽  
Test Results ◽  
Loading Tests ◽  
Reversed Loading

This research presents a novel self-centering fluidic viscous damper that incorporates preloaded ring springs to offer self-centering capability and a fluidic viscous damper for energy dissipation. A full-scale self-centering fluidic viscous damper was developed and subjected to low-cyclic reversed loading tests. The test results show the self-centering fluidic viscous damper has both displacement-dependent and velocity-dependent hysteric responses with self-centering capability. Fatigue tests further show that the self-centering fluidic viscous damper maintains a stable hysteretic response under reversed loading. An analytical model and a numerical model are developed for the proposed self-centering fluidic viscous damper and analyzed. Comparisons of test results and the numerical and analytical models show similar hysteric responses, thereby validating the accuracy of the numerical and analytical models to simulate the behavior of the proposed damper.

Mathematical Modeling of Heat Transfer in Laser Surface Hardening of AISI 1050 Steel

2011 ◽  
Vol 312-315 ◽  
pp. 381-386
Author(s):  
R. Sh. Razavi ◽  
G.R. Gordani ◽  
S. Tabatabaee
Keyword(s):  
Mathematical Modeling ◽  
Heat Transfer ◽  
Surface Hardening ◽  
Laser Energy ◽  
Hardened Layer ◽  
Laser Surface ◽  
Material Surface ◽  
Laser Surface Hardening ◽  
Proposed Model ◽  
Good Agreement

Laser surface hardening is a method used for surface modification without affecting the bulk properties of materials. Due to rapid cooling and little thermal penetration in the surface layer, a homogenous structure and little distortion are usually obtained. When a high power laser irradiates a material surface, a part of the laser energy is absorbed and conducted into the interior of the material. If the absorbed energy is high enough, the material surface will melt and even vaporizes. Consequently the temperature of the process is of promote importance to incorporate an appropriate structural layer. In this regard, a study has been carried out to implement a mathematical modeling method to control the temperature gradient, which affects on the depth of the hardened layer. The model is based on solving the heat transfer equation and such a condition by assuming that the thermo-physical properties of the material are independent of the temperature. To evaluate the application of the proposed model, laser surface hardening was carried out to AISI 1050 steel, using a 1 kW CO2 laser. It was shown that the experimental results obtained are in good agreement with the proposed model.

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