scholarly journals Influence of friction in a case of impact simulation

2020 ◽  
Vol 12 (4) ◽  
pp. 145-154
Author(s):  
George-Ghiocel OJOC ◽  
Viorel Totolici RUS ◽  
Christian POPESCU ◽  
Catalin PIRVU ◽  
Lorena DELEANU
Keyword(s):  
Experimental Data ◽  
Constitutive Model ◽  
Time Moment ◽  
Von Mises Stress ◽  
Rigid Plate ◽  
Impact Simulation ◽  
Maximum Value ◽  
Opposite Face ◽  
Von Mises ◽  
The Impact

This paper presents an analysis of two cases, simulating the impact of a cylindical projectile on a perfectly rigid plate. One case is run without friction, the second one is run taking into account a friction coeficient between the plate and the projectile. The authors used for the projectile the same material constitutive model for both cases, based on experimental data and model developed by Johnson and Cook. Here, the comparing criteria were the maximum value of von Mises stress, the velocity and acceleration of the central point on the opposite face to the contact face of the projectile. Introducing friction, the simulation is more realistic. Taking into account friction, the projectile is less deformed and there was no edge breakage, at the same time moment.

scholarly journals INFLUENCE OF ELEMENT SIZE IN A CASE OF IMPACT SIMULATION

2021 ◽  
Vol 10 (4) ◽  
pp. 24-29
Author(s):  
Viorel TOTOLICI RUSU ◽  
George Ghiocel OJOC ◽  
Catalin PIRVU ◽  
Lorena DELEANU
Keyword(s):  
Mesh Size ◽  
Cylindrical Body ◽  
Von Mises Stress ◽  
Deformation And Failure ◽  
Impact Simulation ◽  
Element Size ◽  
Maximum Value ◽  
Case Application ◽  
Von Mises ◽  
Computer Resources

This paper presents an analysis of data resulting from the same material constitutive model, based on experimental data and model developed by Johnson and Cook. The same case of impacting a cylindrical body on a perfectly rigid target was run with four different mesh size (2 mm, 1 mm, 0.5 mm and 0.25 mm). Here, the comparing criterion was the maximum value of von Mises stress and the authors pointed out that the finest mesh here presented is closer to reality. Depending on the case application the engineers could adopt a finer or coarse mesh, but not so coarse to denaturate the reality of body deformation and failure. How to decide? Having performant computer resources (hardware and software) and running several mesh in order to notice the convergence of one parameter or, more reliable, a set of criteria that could include qualitative resemblance with actual bodies as concerning failure and deformation, experimental dat on strain, yield and failure of the involved materials, values of stress and strain, at the same time moments. From this study the following conclusions were formulated: finer mesh presents a earlier failure in time and calculated a higher stress for these moment.

The Adaptive Blade Design and Evaluation of Wind Turbine

2010 ◽  
Vol 97-101 ◽  
pp. 2318-2323
Author(s):  
Wang Yu Liu ◽  
Jia Xing Gong ◽  
Xi Feng Liu ◽  
Xin Zhang
Keyword(s):  
Wind Turbine ◽  
Medial Axis ◽  
Coupling Effect ◽  
Design Method ◽  
Von Mises Stress ◽  
Blade Design ◽  
Adaptive Performance ◽  
Laminar Shear Stress ◽  
Von Mises ◽  
The Impact

This article explored the design method of the wind turbine blade being of flapping-twist adaptive performance and how to evaluate its feasibility and reliability according to the comprehensive factors. The results indicate that both spar cap and skin with off-axis carbon fiber can achieve the efficient flapping-twist coupling effect. Through overall investigation, the results show that the maximum fiber strains of tensile and compressive go up with increase of the off-axis angle, and the peak inter-laminar shear stress increase more rapidly. While, all of these evaluating indicators should be kept in the reference range for used materials. Moreover, when the off-axis angle increases, the peak Von Mises stress declines. In addition, the impact of natural frequencies on the blade design is proved to be insignificant. Finally, utilizing the medial axis laminates in the blade decoupled area is helpful to strengthen the blade fatigue resistivity.

Examination of the Stress Distribution in the Tip of a Pencil

2005 ◽  
Vol 73 (2) ◽  
pp. 335-337
Author(s):  
E. Pogozelski ◽  
D. Cole ◽  
M. Wesley
Keyword(s):  
Stress Distribution ◽  
Fracture Surface ◽  
Initial Position ◽  
Von Mises Stress ◽  
Shear Stresses ◽  
Worst Case ◽  
Position And Orientation ◽  
Von Mises ◽  
The Impact ◽  
Normal And Shear Stresses

The stresses within the tip of a pencil are examined theoretically, numerically, and experimentally to determine the position and orientation of the fracture surface. The von Mises stress is used to evaluate the impact of the normal and shear stresses due to compression, bending, torsion, and shear. The worst-case stress is shown to occur along the top edge of the inclined pencil point, where the normal stress is compressive. The resulting crack propagates diagonally downwards and towards the tip from this initial position, and is frequently observed to contain a cusp.

scholarly journals Numerical Analysis of the Crack Inspections Using Hybrid Approach for the Application the Circular Cantilever Rods

2021 ◽  
Vol 29 (2) ◽  
Author(s):  
Saddam Hussein Raheemah ◽  
Kareem Idan Fadheel ◽  
Qais Hussein Hassan ◽  
Ashham Mohammed Aned ◽  
Alaa Abdulazeez Turki Al-Taie ◽  
...  
Keyword(s):  
Structural Design ◽  
Hybrid Approach ◽  
Von Mises Stress ◽  
Whole Body ◽  
Total Deformation ◽  
Motion Equations ◽  
Maximum Deformation ◽  
Simulation Process ◽  
Maximum Value ◽  
Von Mises

The present study aims to investigate crack presence in a rigid steel beam so that it can be considered in structural design. A finite element method (FEM) had been used with the Ansys 16.1 software to simulate the whole steel body with three different forces and moments with a magnitude force subjected at the free end of the beam. The steel rod had been considered as simple cantilever to be modelled by the software. Von Mises stress had been considered in the simulation process where the maximum value of stress due to applied load and moment was 1.9 MPa. Total deformation of the whole body had also been considered to instigate the maximum deformation (4.3mm) due to applied loads and moments. Furthermore, MATLAB and through fuzzy logic had been used to assist in the investigation of cracks. Both approaches had been governed by the Euler-Bernoulli theory for free vibration of motion equations. The other aim of this study is to evaluate results received from the Ansys with MATLAB for the same boundary conditions as the case.

Investigation of Meniscus Effect on Microbond Test of Typha Fiber/Epoxy Matrix

2020 ◽  
Vol 402 ◽  
pp. 14-19
Author(s):  
Andri Afrizal ◽  
Ikramullah ◽  
Syarizal Fonna ◽  
Syifaul Huzni
Keyword(s):  
Epoxy Matrix ◽  
Maximum Stress ◽  
Interfacial Shear Strength ◽  
Von Mises Stress ◽  
Microbond Test ◽  
The Matrix ◽  
The Difference ◽  
Von Mises ◽  
The Impact ◽  
Fiber Radius

The microbond test was one of the methods to examine the interfacial shear strength (IFSS) value of fiber and polymer matrix. The meniscus angle that formed at both ends of the matrix is difficult to control while manufacturing the specimen for the microbond test. Therefore, the effect of meniscus angle must be evaluated. In this paper, we evaluated the impact of variations of the meniscus angle against the maximum von-mises stress and the IFSS value of the Typha fiber epoxy matrix by finite element method. The geometry of the microbond test specimen was modeled with 0.25 mm fiber radius, 2 mm fiber length, 1.75 mm embedded length of the matrix, and varied the meniscus angles with 22°, 30°, 45°, 60°, 75°, and 90°. The mesh type quad-dominated CAX4R is used on fiber and matrix, while quad COHAX4 is applied to the cohesive element between fiber and matrix. The constantly applied displacement was adjusted to the upper end of the fiber at 0.6 mm. The simulation results showed that the difference in maximum stress obtained in each model. Furthermore, that is not given much difference in IFSS value. It can be concluded that the meniscus angle affects the maximum von-mises stress but not too much-affected IFSS value of the fiber and epoxy matrix.

scholarly journals Multi-layered bird beaks: a finite-element approach towards the role of keratin in stress dissipation

2012 ◽  
Vol 9 (73) ◽  
pp. 1787-1796 ◽  
Author(s):  
Joris Soons ◽  
Anthony Herrel ◽  
Annelies Genbrugge ◽  
Dominique Adriaens ◽  
Peter Aerts ◽  
...  
Keyword(s):  
Finite Element ◽  
Material Properties ◽  
Speckle Pattern ◽  
Young Modulus ◽  
Von Mises Stress ◽  
Fe Model ◽  
Element Approach ◽  
Von Mises ◽  
The Impact

Bird beaks are layered structures, which contain a bony core and an outer keratin layer. The elastic moduli of this bone and keratin were obtained in a previous study. However, the mechanical role and interaction of both materials in stress dissipation during seed crushing remain unknown. In this paper, a multi-layered finite-element (FE) model of the Java finch's upper beak ( Padda oryzivora ) is established. Validation measurements are conducted using in vivo bite forces and by comparing the displacements with those obtained by digital speckle pattern interferometry. Next, the Young modulus of bone and keratin in this FE model was optimized in order to obtain the smallest peak von Mises stress in the upper beak. To do so, we created a surrogate model, which also allows us to study the impact of changing material properties of both tissues on the peak stresses. The theoretically best values for both moduli in the Java finch are retrieved and correspond well with previous experimentally obtained values, suggesting that material properties are tuned to the mechanical demands imposed during seed crushing.

scholarly journals Effects of Shroud Curvature on the Performance of Centrifugal Compressor Blade

2011 ◽  
Vol 2-3 ◽  
pp. 700-705
Author(s):  
Kai Yuan Hao ◽  
Wei Min Wang ◽  
Yong Qiang Shi ◽  
Sha Sha Wang
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Axial Length ◽  
Mechanical Analysis ◽  
Von Mises Stress ◽  
Centrifugal Impeller ◽  
Finite Element Analyses ◽  
Computational Fluid Dynamics Cfd ◽  
Von Mises ◽  
The Impact

The purpose of the study described in this paper was to investigate the impact of shroud curvature on the performance of a centrifugal impeller or stage. The paper discusses a computational fluid dynamics (CFD) study done to assess the influence of shroud curvature on impeller performance. The computational fluid dynamics (CFD) and finite element analyses (FEA) methods were used to describe the various designs of the impeller. Aerodynamic and mechanical analysis results are presented for four impellers of varying cover curvature and axial length. The aerodynamic results showed there were clear aerodynamic benefits to decreasing the curvature along the impeller shroud. The mechanical analytical results showed that the impeller with the lowest curvature or longest axial length provided the highest performance; it also yielded the lowest Von Mises stress level. In closing, there are clear aerodynamic benefits to decreasing the curvature along the impeller shroud but these benefits must be weighed against the impact on the rotordynamic considerations Comments are offered regarding the rotordynamic issues that must be considered when increasing the length of impellers.

scholarly journals Analysis of rolling on steel and rubber-covered rollers using viscoelasticity

2019 ◽  
Vol 11 (11) ◽  
pp. 168781401988980
Author(s):  
Hongyan Chu ◽  
Qi Chen ◽  
Rui Wang ◽  
Yingjie Hong
Keyword(s):  
Constitutive Model ◽  
Working Conditions ◽  
Constitutive Models ◽  
Von Mises Stress ◽  
Dimensional Structure ◽  
Control Group ◽  
Shore Hardness ◽  
Viscoelastic Composite ◽  
Contact Width ◽  
Von Mises

In this article, a series of analysis were performed on a two-dimensional structure of steel and rubber-covered rollers. First, a hyperelastic–viscoelastic composite constitutive model based on a dynamic mechanical experiment of rubber was formulated to accurately describe rubber properties. Meanwhile, a hyperelastic constitutive model not considering viscoelasticity was set as the control group. The material used in this article was the nitrile rubber with the Shore hardness of 40. Then, the effects of viscoelasticity on the von Mises stress were analyzed by comparing results of two models. The influences of working conditions (roller speeds/compression displacement) on the von Mises stress and the area of hysteresis loop were also studied. Next, the contact characteristics under different working conditions and constitutive models were analyzed combining viscoelasticity. A verification experiment of contact width was carried out, and the theoretical and simulated values were calculated and compared. Finally, the relation of “low peak” phenomenon with viscoelasticity was studied, and the effects of working conditions and rubber viscoelasticity on contact feature of rollers were summarized. The conclusions of the article can help engineers to better optimize dynamic working conditions and judge the working state of the structure.

The Design and Analysis of Universal Inertial Switch Based MEMS

2012 ◽  
Vol 157-158 ◽  
pp. 308-311
Author(s):  
Yong Ping Hao ◽  
Li Ya Bao ◽  
Shuang Xi Gu
Keyword(s):  
Response Time ◽  
High Speed ◽  
Maximum Stress ◽  
Von Mises Stress ◽  
Inertial Switch ◽  
Von Mises ◽  
Continuous Power ◽  
The Impact ◽  
Fast Acting ◽  
Speed Response

In this paper, a novel MEMS inertial switch is designed and characterized for the purpose of crash sensing for ammunition systems in which high-speed response is required for triggering the detonator. In order to keep the same sensitivity in different direction, the structure of an annular proof-mass suspended by four serpentine flexures is designed. The switch can be integrated with electronics, fast-acting，and lack of a requirement for continuous power, and can be used in a wide area. The motion of the inertial switch is analyzed by dynamic simulation under the 700g threshold acceleration in y direction, the simulation results show that the response time is 0.142ms and the contact time of the switch is about 5 , it illustrates that the response time is short enough and the impact time satisfy the ask. The von-mises stress of the structure is calculate, the maximum stress occurs in the serpentine flexures, the value is 60.61 MPa, much less than the yield strength of the silicon, the switch can be used time after time.

The Impact Response Characteristics Research of the Multilayer Structure, Cantilever-Type Electrothermal Actuator Based on MEMS

2014 ◽  
Vol 901 ◽  
pp. 87-92
Author(s):  
Ya He Wang ◽  
Yue Yue Shen ◽  
Chao Lv
Keyword(s):  
Multilayer Structure ◽  
Fem Simulation ◽  
Impact Response ◽  
Von Mises Stress ◽  
Beam Model ◽  
The Finite Element Method ◽  
Response Characteristics ◽  
Von Mises ◽  
Fixed End ◽  
The Impact

To study the impact response characteristics of multilayer structure, cantilever-type electrothermal actuators based on MEMS, a composite cantilever-beam model consisting of two layers of materials, SiO2 and Al, is built. By using the engineer mechanics theory, the von mise stress under the impacts in the fuze system can be obtained. Meanwhile, the Finite Element Method (FEM) simulation is made to get the deformation displacement of the fixed end and the von mises stress distribution of the model. Besides, the natural frequency response is studied. The results present the actuators response characteristics of impacts in the fuze system.

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