scholarly journals Development of New Baseball Pitching Machine with Four-Roller Throwing Mechanism

Proceedings ◽  
2020 ◽  
Vol 49 (1) ◽  
pp. 8
Author(s):  
Shinobu Sakai ◽  
Jin-Xing Shi
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Rotational Speed ◽  
Spin Axis ◽  
Element Analysis ◽  
Wide Range

At present, there are only a few developed pitching machines that can throw a ball with gyro spin. In this study, we aimed to develop a new baseball pitching machine using four rollers, where the rotational speed of each of the four rollers and the crossing angle of the opposite gyro rollers can be controlled optionally to generate an objective gyro spin more efficiently. We also elucidate the throwing mechanism of the developed baseball pitching machine and confirm its performance by finite element analysis. The newly developed pitching machine can throw a baseball with a wide range of speeds from 22.2 m/s (80 km/h) to 44.4 m/s (160 km/h) with all pitch types (fastball, curveball, gyroball, etc.), and the spin axis can be controlled in any designated direction. Moreover, this machine is capable of throwing a baseball with higher accuracy compared to commercially available pitching machines.

Fabrication and finite element analysis of vibrating parallel film actuator made with cellulose acetate for potential haptic application

2016 ◽  
Vol 230 (15) ◽  
pp. 2720-2727 ◽  
Author(s):  
Md Mohiuddin ◽  
Asma Akther ◽  
Eun Byul Jo ◽  
Hyun Chan Kim ◽  
Jaehwan Kim
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Cellulose Acetate ◽  
Vibration Characteristics ◽  
Experimental Results ◽  
Vibration Velocity ◽  
Frequency Range ◽  
Actuation Frequency ◽  
Element Analysis ◽  
Wide Range

The present study investigates a film actuator made with dielectric cellulose acetate films separated by narrow spacers as a means of electrostatic actuation for potential haptic application. Fabrication process for the actuator is explained along with experiments conducted over a wide frequency range of actuation frequency. A valid finite element simulation of the actuator is made on the quarter section of the actuator by using full 3D finite elements. Vibration characteristics such as fundamental natural frequency, mode shape and output velocity in the frequency range for haptic feeling generation are obtained from the finite element analysis and compared with the experimental results. Experimental results demonstrate that the finite element model is practical and effective enough in predicting the vibration characteristics of the actuator for haptic application. The film actuator shows many promising properties like high transparency, wide range of actuation frequency and high vibration velocity for instance.

Effects of Ultrasonic Motor Stator Teeth Height on Start Reliability

2015 ◽  
Vol 0 (0) ◽  
Author(s):  
Wei Zheng ◽  
Jing-Liang Zhou ◽  
Yu-Zhen Ruan
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Traveling Wave ◽  
Ultrasonic Motor ◽  
Wave Type ◽  
Element Analysis ◽  
Factors Affecting ◽  
Ultrasonic Motors ◽  
Wide Range ◽  
New Type

AbstractAs a new type of motor, the traveling wave type rotary ultrasonic motors (TRUM) have a wide range of applications. However, the friction between stator and rotor leads to its poor start reliability, which retards the progress of application of ultrasonic motors. Sometimes TRUMs which are widely used cannot start after storage. Height of tooth of the ultrasonic motor’s stator is one of the factors affecting TRUM’s start stabilizing. In this paper, combined with the ultrasonic motor running mechanism, the factors that affect TRUM’s start reliability are studied. Model of ultrasonic motor stator tooth height is analyzed by finite element analysis (FEA). Five TRUMs with different tooth heights are fabricated and measured. A TRUM with 1.85 mm tooth height can start properly in humidity 90%, but ultrasonic motors with 1.8–1.9 mm tooth height cannot start properly under the same conditions.

scholarly journals Multistage Tool Path Optimisation of Single-Point Incremental Forming Process

Materials ◽  
2021 ◽  
Vol 14 (22) ◽  
pp. 6794
Author(s):  
Zhou Yan ◽  
Hany Hassanin ◽  
Mahmoud Ahmed El-Sayed ◽  
Hossam Mohamed Eldessouky ◽  
Joy Rizki Pangestu Djuansjah ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Processing Time ◽  
Incremental Forming ◽  
Single Point ◽  
Computational Time ◽  
Single Point Incremental Forming ◽  
Two Stage ◽  
Element Analysis ◽  
Wide Range

Single-point incremental forming (SPIF) is a flexible technology that can form a wide range of sheet metal products without the need for using punch and die sets. As a relatively cheap and die-less process, this technology is preferable for small and medium customised production. However, the SPIF technology has drawbacks, such as the geometrical inaccuracy and the thickness uniformity of the shaped part. This research aims to optimise the formed part geometric accuracy and reduce the processing time of a two-stage forming strategy of SPIF. Finite element analysis (FEA) was initially used and validated using experimental literature data. Furthermore, the design of experiments (DoE) statistical approach was used to optimise the proposed two-stage SPIF technique. The mass scaling technique was applied during the finite element analysis to minimise the computational time. The results showed that the step size during forming stage two significantly affected the geometrical accuracy of the part, whereas the forming depth during stage one was insignificant to the part quality. It was also revealed that the geometrical improvement had taken place along the base and the wall regions. However, the areas near the clamp system showed minor improvements. The optimised two-stage strategy successfully decreased both the geometrical inaccuracy and processing time. After optimisation, the average values of the geometrical deviation and forming time were reduced by 25% and 55.56%, respectively.

Application of subloading-overstress friction model to finite element analysis

2014 ◽  
Vol 4 (2) ◽  
Author(s):  
T. Kuwayama ◽  
K. Hashiguchi ◽  
N. Suzuki ◽  
N. Yoshinaga ◽  
S. Ogawa
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Flat Surface ◽  
Surface Friction ◽  
Friction Model ◽  
Sliding Velocity ◽  
Element Analysis ◽  
Contact Behaviour ◽  
Wide Range ◽  
The Finite Element Analysis

Accurate prediction of contact behaviour between machine tools and metals is required for the mechanical design of machinery. In this article, the numerical analysis of the contact behaviour is described by incorporating the subloading-overstress model [6] which is capable of describing the contact behaviour for a wide range of sliding velocity including the increase of coefficient of friction with the increase of sliding velocity. And its validity is verified by the comparison with some test results. First, in order to examine the influence of sliding velocities on the friction properties, the flat-surface friction tests for lubricated interfaces between galvannealed steel sheet and SKD-11 tool steel were performed. As a result, It is observed that the friction smoothly translate to kinetic friction, after exhibiting the peak at the static friction. In addition, it is observed that the higher the sliding velocity, the larger the friction resistance, meaning the positive rate sensitivity. Then the subloading-overstress model is implemented in the finite element analysis program ABAQUS/Standard, and it is used to simulate the flat-surface friction tests. The predictions from the finite element analysis are shown to be in very good agreement with experimental results.

A three‐dimensional strain concentration equation for countersunk holes

2008 ◽  
Vol 43 (2) ◽  
pp. 75-85 ◽  
Author(s):  
A Bhargava ◽  
K N Shivakumar
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Concentration Factor ◽  
Three Dimensional ◽  
Structural Elements ◽  
Element Analysis ◽  
Strain Concentration ◽  
Wide Range ◽  
Dimensional Equation ◽  
Concentration Equation

Countersunk rivets are used to join components to achieve aerodynamic or hydrodynamic surfaces. At countersunk holes, three‐dimensional stress and strain concentrations occur. Previously, the present authors developed a three‐dimensional equation for the stress concentration factor Kt through a detailed finite element analysis. This paper extends the study to include an equation for three‐dimensional strain concentration factor Ktε using a similar approach. The resulting equation was verified by finite element analysis for a wide range of countersunk hole configurations and plate sizes. Results showed that the maximum strain concentration is at the countersunk edge. The developed equation is within 5 per cent of the finite element results for all practical cases. It was also found that the Ktε and Kt expressions are similar and Ktε≥ Kt. The maximum difference between the two is 8 per cent (for = 0.3) or 2 for straight‐shank holes and about 2/2 for countersunk holes. The proposed equation is a valuable tool for strain‐based design of structural elements.

Constraint-Based Fracture Mechanics Analysis of Cylinders With Circumferential Cracks

2009 ◽  
Author(s):  
Michael Bach ◽  
Xin Wang ◽  
Robert Bell
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Carrying Capacity ◽  
Load Carrying Capacity ◽  
Element Analysis ◽  
Fracture Parameters ◽  
Wide Range ◽  
Load Carrying ◽  
T Stress ◽  
Low Constraint

In this paper, the fracture behaviour of hollow cylinders with internal circumferential crack under tensile loading is examined extensively. Finite element analysis of the cracked cylinders is conducted to determine the fracture parameters including stress intensity factor, T-stress, and J-integral. Linear elastic finite element analysis is conducted to obtain K and T-stress, and elastic plastic analysis is conducted to obtain fully plastic J-integrals. A wide range of cylinder geometries are studied, with cylinder thickness ratios of ri/ro = 0.2 to 0.8 and crack depth ratio a/t = 0.2 to 0.8. These fracture parameters are then used to construct conventional and constraint-based failure assessment diagrams (FADs) to determine the maximum load carrying capacity of cracked cylinders. It is demonstrated that these tensile loaded cylinders with circumferential cracks are under low constraint conditions, and the load carrying capacity are higher when the low constraint effects are properly accounted for, using constraint-based FADs, comparing to the predictions from the conventional FADs.

Finite Element Analysis of the Effect of Mechanical Stress Improvement Process on Weld Residual Stress and Flaw Growth in a Thick-Walled Pressurizer Safety Nozzle

2017 ◽  
Author(s):  
Giovanni G. Facco ◽  
Patrick A. C. Raynaud ◽  
Michael L. Benson
Keyword(s):  
Residual Stress ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Stress Field ◽  
Mechanical Stress ◽  
Residual Stress Field ◽  
Element Analysis ◽  
Wide Range ◽  
Improvement Process ◽  
Stress Prediction

The Mechanical Stress Improvement Process (MSIP) is generally accepted as an effective method to modify the residual stress field in a given component to mitigate subcritical crack growth in susceptible components [1] [2] [3]. In order to properly utilize MSIP, residual stress prediction is needed to determine the parameters of the MSIP application and the expected final residual stress field in the component afterwards. This paper presents the results of a 2D axisymmetric finite element study to predict weld residual stresses (WRS), and associated flaw growth scenarios, in a thick-walled pressurizer safety nozzle that underwent mitigation by application of MSIP. The authors have developed a finite-element analysis methodology to examine the effect of MSIP application on WRS and flaw growth for various hypothetical welding histories and boundary conditions in a thick-walled pressurizer safety nozzle. In doing so, a wide range of repair scenarios was considered, with the understanding that some bounding scenarios may be impractical for this geometry.

New realistic hypothesis on corner stiffness of right-angle frames for increased analysis accuracy

2015 ◽  
Vol 231 (9) ◽  
pp. 1738-1748
Author(s):  
Young-Doo Kwon ◽  
Jin-Sik Han
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Equivalent Stress ◽  
Frame Structure ◽  
Element Analysis ◽  
Optimal Dimension ◽  
Various Boundary Conditions ◽  
Wide Range ◽  
Von Mises ◽  
Comparison Of The Results

Structural elements like bars, trusses, beams, frames, plates, and shells have long been used in structures and machines because of their large stiffness-to-weight ratios. The Euler–Bernoulli theory for beam elements is currently used in a wide range of engineering fields. Frames may essentially be considered to be a type of general beam with axial loads. In the analysis of a right-angle frame, the stiffness of a corner has been assumed to be infinite, which is allowable only when the frame is sufficiently slender. However, a comparison of the results of a finite element analysis showed that the assumption of rigid corner stiffness is unacceptable for most cases because of the considerable errors that result. To resolve this problem, we assumed that the stiffness of a corner in a right-angle frame was finite, which is mostly the case, and solved the problem of a right-angle frame with round corners under internal pressure. Using the derived formula based on the assumption of finite corner stiffness and the formula for the round corner stiffness, we analyzed the entire right-angle frame structure and compared the results to finite element analysis results. As a final attempt, the quasi-optimal dimension of the corner was found to exhibit the lowest von Mises equivalent stress. This proposed approach could be applied to many problems involving frames with various boundary conditions to improve the accuracy.

An Improved Heat Equation for Fully Coupled Thermal-Structural Finite Element Analysis Using Small Strain Formulation

2014 ◽  
Vol 611 ◽  
pp. 294-303
Author(s):  
Ladislav Écsi ◽  
Pavel Élesztős
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Heat Equation ◽  
Mathematical Formulation ◽  
Model Verification ◽  
Cyclic Plasticity ◽  
Ductile Material ◽  
Element Analysis ◽  
Wide Range ◽  
Fully Coupled

In this paper an improved heat equation for fully coupled thermal structural finite element analysis is presented. In the problem solving process, mathematical formulation appropriate strain measures describing the onset and the growth of ductile and total damage and heat generation rate per unit volume for dissipation-induced heating have been employed. The model was implemented into a finite element code using an improved weak form for fully coupled thermal structural finite element analysis, an extended NoIHKH material model with internal damping for cyclic plasticity of metals capable of modelling ductile material behaviour in wide range of strain rates. A notched aluminium alloy specimen in cyclic tension using 2Hz excitation frequency and linearly increasing amplitude has been studied. The model verification showed excellent agreement with available experiments. A few selected analysis results are presented and briefly discussed.

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