scholarly journals Mechanistic Force Modeling for Broaching Process

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Raghavendra Kamath Cholpadi ◽  
Appu Kuttan
Keyword(s):  
Dynamic Model ◽  
Natural Frequency ◽  
Experimental Work ◽  
Model Parameters ◽  
Force Model ◽  
Damping Coefficients ◽  
Force Modeling ◽  
Dynamic Forces ◽  
Stiffness And Damping ◽  
Experimental Corroboration

There is a demand for mechanistic force model that can predict and simulate the broaching process. In this paper, an attempt has been made for mechanistic force modeling of the broaching operation and experimental corroboration with the simulated result. The stiffness and damping coefficients for dynamic model are computed from the natural frequency of the broaching system and actual damped natural frequency has been obtained experimentally. Experimental work has been carried to compute the dynamic model parameters such as mass, stiffness, and damping coefficients. The simulated dynamic forces are illustrated graphically and are closely in agreement with the results obtained through manual broaching process.

scholarly journals Dynamic Forces of Swaying Human and Responses of Temporary Demountable Grandstand Based on Experiment and Simulation

2018 ◽  
Vol 2018 ◽  
pp. 1-22
Author(s):  
Lin He ◽  
Jian Yuan ◽  
Feng Fan ◽  
Cong Liu
Keyword(s):  
Force Plate ◽  
Dynamic Responses ◽  
Experimental Program ◽  
Force Model ◽  
Lateral Vibration ◽  
Structural Dynamic ◽  
Important Research Topic ◽  
Dynamic Forces ◽  
Semiempirical Formula ◽  
Stiffness And Damping

Modern temporary demountable structures must be designed to withstand the dynamic forces which generated by crowd occupants. The human forces and that cause the dynamic responses of structure have become an important research topic. In this paper, the human swaying forces and responses of temporary demountable grandstand are studied through an experimental program. The dynamic forces that were induced by participants who have swayed 0.5–1.8 Hz are recorded by a triaxial human biomechanics force plate, and the structural dynamic responses of a temporary grandstand occupied twenty swaying human are investigated. The constraint parameters of swaying force model which derives from a semiempirical formula are developed and can be represented for crowd. Crowd can able to induce excessive lateral vibration of structure due to the lower frequency of temporary grandstand and make them in panic. The dynamic responses of a large temporary grandstand are predicted by finite element method, and the results show that a person was considered as a load with stiffness and damping, and the structural lateral dynamic responses are higher than the model of person just only considered as load.

A Nonlinear Dynamic Model With Confidence Bounds for Hydrodynamic Bearings

1998 ◽  
Vol 120 (3) ◽  
pp. 595-604 ◽  
Author(s):  
Chin S. Chu ◽  
Kristin L. Wood ◽  
Ilene J. Busch-Vishniac
Keyword(s):  
Dynamic Model ◽  
Nonlinear Dynamic ◽  
Small Amplitude ◽  
Taylor Series Expansion ◽  
Higher Order ◽  
Slider Bearing ◽  
Nonlinear Dynamic Model ◽  
Hydrodynamic Bearings ◽  
Damping Coefficients ◽  
Stiffness And Damping

In conventional rotordynamic modeling, hydrodynamic bearings are often characterized by a set of linear stiffness and damping coefficients obtained from a first-order Taylor series expansion of bearing reactions. Theoretically, these coefficients are only valid for small amplitude motion about an equilibrium position. In this paper, a nonlinear dynamic model that overcomes the small amplitude assumption in the conventional linear analysis is described. By including higher-order terms in the bearing reaction expansion, nonlinearity in the oil film forces for large amplitude motion can be captured and represented by a set of nonlinear stiffness and damping coefficients. These coefficients are functions of static bearing displacement. A finite difference approach is described and is used to solve for these coefficients. The stated model is applied to a conventional slider bearing and a mechanical smart slider bearing that experiences large variations in load. Error assessment is performed numerically on the higher-order solutions to determine an acceptable displacement bound for the higher order coefficients.

scholarly journals Dynamic Model of the Hot Strip Rolling Mill Vibration Resulting from Entry Thickness Deviation and Its Dynamic Characteristics

2019 ◽  
Vol 2019 ◽  
pp. 1-11 ◽  
Author(s):  
Xinxin Wang ◽  
Xiaoqiang Yan
Keyword(s):  
Dynamic Model ◽  
Dynamic Characteristics ◽  
Rolling Mill ◽  
Model Parameters ◽  
Force Model ◽  
Hot Strip Rolling ◽  
Strip Rolling ◽  
Hot Strip ◽  
Thickness Deviation ◽  
Rolling Mill Vibration

The vibration demolding of the crystallizer leads to slab thickness deviation in continuous casting processes. Therefore, in this paper, the dynamic model of the hot strip rolling mill vibration resulting from entry thickness deviation is proposed and its dynamic characteristics are studied. First, the dynamic model of vertical vibration in the hot strip rolling mill is established based on Sims’ rolling force model. Then, the model validity is certified by comparing the simulation with field test data from a 1580 hot strip rolling mill. Finally, we investigate the influence of model parameters on the dynamic characteristics of hot strip rolling mill vibration resulting from entry thickness deviation. The result indicates that hot strip rolling mill vibration resulting from entry thickness deviation can be reduced by increasing the area of the hydraulic cylinder piston side and the entry thickness as well as by decreasing the deformation resistance, rolling speed, and equivalent stiffness.

Ball bearing turbocharger vibration management: application on high speed balancer

2020 ◽  
Vol 21 (6) ◽  
pp. 619
Author(s):  
Kostandin Gjika ◽  
Antoine Costeux ◽  
Gerry LaRue ◽  
John Wilson
Keyword(s):  
Dynamic Behavior ◽  
High Speed ◽  
Internal Combustion Engines ◽  
Ball Bearing ◽  
Squeeze Film ◽  
Design And Technology ◽  
Squeeze Film Damper ◽  
Damping Coefficients ◽  
Bearing Loads ◽  
Stiffness And Damping

Today's modern internal combustion engines are increasingly focused on downsizing, high fuel efficiency and low emissions, which requires appropriate design and technology of turbocharger bearing systems. Automotive turbochargers operate faster and with strong engine excitation; vibration management is becoming a challenge and manufacturers are increasingly focusing on the design of low vibration and high-performance balancing technology. This paper discusses the synchronous vibration management of the ball bearing cartridge turbocharger on high-speed balancer and it is a continuation of papers [1–3]. In a first step, the synchronous rotordynamics behavior is identified. A prediction code is developed to calculate the static and dynamic performance of “ball bearing cartridge-squeeze film damper”. The dynamic behavior of balls is modeled by a spring with stiffness calculated from Tedric Harris formulas and the damping is considered null. The squeeze film damper model is derived from the Osborne Reynolds equation for incompressible and synchronous fluid loading; the stiffness and damping coefficients are calculated assuming that the bearing is infinitely short, and the oil film pressure is modeled as a cavitated π film model. The stiffness and damping coefficients are integrated on a rotordynamics code and the bearing loads are calculated by converging with the bearing eccentricity ratio. In a second step, a finite element structural dynamics model is built for the system “turbocharger housing-high speed balancer fixture” and validated by experimental frequency response functions. In the last step, the rotating dynamic bearing loads on the squeeze film damper are coupled with transfer functions and the vibration on the housings is predicted. The vibration response under single and multi-plane unbalances correlates very well with test data from turbocharger unbalance masters. The prediction model allows a thorough understanding of ball bearing turbocharger vibration on a high speed balancer, thus optimizing the dynamic behavior of the “turbocharger-high speed balancer” structural system for better rotordynamics performance identification and selection of the appropriate balancing process at the development stage of the turbocharger.

A novel model of Z-pin insertion in prepreg based on fracture mechanics

2021 ◽  
pp. 095440542110144
Author(s):  
Guobiao Ji ◽  
Liang Cheng ◽  
Shaohua Fei ◽  
Jiangxiong Li ◽  
Yinglin Ke
Keyword(s):  
Fracture Toughness ◽  
Fracture Mechanics ◽  
Analytical Model ◽  
Model Parameters ◽  
Force Model ◽  
Fe Model ◽  
Cohesive Elements ◽  
Fe Method ◽  
Insertion Force ◽  
Mechanics Model

Through-thickness reinforcement is a promising solution to the problem of delamination susceptibility in laminated composites. Modeling Z-pin–prepreg interaction is essential for accurate robotics-assisted Z-pin insertion. In this paper, a novel Z-pin insertion force model combining the classical cohesive finite element (FE) method with a dynamic analytical fracture mechanics model is proposed. The velocity-dependent cohesive elements, in which the fracture toughness is provided by the analytical model, are implemented in Z-pin insertion FE model to predict the crack initiation and propagation. Then Z-pin insertion experiments are performed on prepreg sample with metallic Z-pins at different velocities to identify the analytical model parameters and validate the simulation predictions offered by the model. Dynamics of Z-pin interaction with inhomogeneous prepreg is described and the effects of insertion velocity on prepreg contact force are studied. Results show that the force model agrees well with experiments and the fracture toughness rises with the increasing Z-pin insertion velocity.

Optimum Design for the Frame of Open Type Abrasive Flow Polish Machine

2012 ◽  
Vol 497 ◽  
pp. 89-93
Author(s):  
Liang Liang Yuan ◽  
Ke Hua Zhang ◽  
Li Min
Keyword(s):  
Finite Element ◽  
Natural Frequency ◽  
Finite Element Methods ◽  
Optimization Design ◽  
Low Cost ◽  
Three Dimensional ◽  
Force Model ◽  
Optimization Analysis ◽  
Open Type ◽  
Set Up

In order to process heterotype hole of workpiece precisely, an open abrasive flow polish machine is designed, and the optimization design of machine frame is done for low cost. Firstly, basing on the parameters designed with traditional ways, three-dimensional force model is set up with the soft of SolidWorks. Secondly, the statics and modal analysis for machine body have been done in Finite element methods (FEM), and then the optimization analysis of machine frame has been done. At last, the model of rebuild machine frame has been built. Result shows that the deformation angle value of machine frame increased from 0.72′ to 1.001′, the natural frequency of the machine decreased from 75.549 Hz to 62.262 Hz, the weight of machine decreased by 74.178 Kg after optimization. It meets the strength, stiffness and angel stiffness requirement of machine, reduces the weight and cost of machine.

Sinusoidal Three-Lobe Bearings—Optimization and Stability Charts

1980 ◽  
Vol 102 (4) ◽  
pp. 416-424 ◽  
Author(s):  
W. E. ten Napel ◽  
R. Bosma
Keyword(s):  
Film Thickness ◽  
Stability Parameters ◽  
Stability Regions ◽  
Damping Coefficients ◽  
Optimum Position ◽  
Minimum Film Thickness ◽  
Stiffness And Damping

In contradistinction to the commonly used segmented three-lobe bearing, another type of bearing, i.e., the sinusoidal three-lobe bearing has been investigated in this paper. The main advantage of this bearing is that it can very easily be manufactured. Special attention has been paid to problems of optimization with regard to minimum film thickness and friction, respectively. Stiffness and damping coefficients have been calculated as well as stability regions and stability parameters. Additionally, the optimum position of the oil grooves has been investigated.

Investigating the vibrational behaviour of a rotating two-blade propeller by using a self-tracking method

2018 ◽  
Vol 233 (3) ◽  
pp. 835-847 ◽  
Author(s):  
Mohammad-Reza Ashory ◽  
Farhad Talebi ◽  
Heydar R Ghadikolaei ◽  
Morad Karimpour
Keyword(s):  
Natural Frequency ◽  
Measurement Errors ◽  
Mode Shapes ◽  
Model Parameters ◽  
Test Results ◽  
Modal Assurance Criterion ◽  
Tracking Method ◽  
Strong Resemblance ◽  
Test Scenarios ◽  
Good Agreement

This study investigated the vibrational behaviour of a rotating two-blade propeller at different rotational speeds by using self-tracking laser Doppler vibrometry. Given that a self-tracking method necessitates the accurate adjustment of test setups to reduce measurement errors, a test table with sufficient rigidity was designed and built to enable the adjustment and repair of test components. The results of the self-tracking test on the rotating propeller indicated an increase in natural frequency and a decrease in the amplitude of normalized mode shapes as rotational speed increases. To assess the test results, a numerical model created in ABAQUS was used. The model parameters were tuned in such a way that the natural frequency and associated mode shapes were in good agreement with those derived using a hammer test on a stationary propeller. The mode shapes obtained from the hammer test and the numerical (ABAQUS) modelling were compared using the modal assurance criterion. The examination indicated a strong resemblance between the hammer test results and the numerical findings. Hence, the model can be employed to determine the other mechanical properties of two-blade propellers in test scenarios.

A Dynamic Model of Magneto-Active Elastomer Actuation of the Waterbomb Base

2014 ◽  
Author(s):  
Landen Bowen ◽  
Mary Frecker ◽  
Timothy W. Simpson ◽  
Paris von Lockette
Keyword(s):  
Dynamic Model ◽  
Special Interest ◽  
Software Package ◽  
Applied Field ◽  
Active Material ◽  
Active Materials ◽  
Stiffness And Damping ◽  
Torsion Springs ◽  
Elastomer Actuation ◽  
Origami Engineering

Of special interest in the growing field of origami engineering is self-folding, wherein a material is able to fold itself in response to an applied field. In order to simulate the effect of active materials on an origami-inspired design, a dynamic model is needed. Ideally, the model would be an aid in determining how much active material is needed and where it should be placed to actuate the model to the desired position. A dynamic model of the origami waterbomb base, a well-known and foundational origami structure, is developed using Adams, a commercial dynamics software package. Creases are approximated as torsion springs with stiffness and damping. The stiffness of an origami crease is calculated, and the dynamic model is verified using the bistability of the waterbomb. An approximation of the torque produced by magneto-active elastomers (MAE) is calculated and is used to simulate MAE-actuated self-folding of the waterbomb.

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