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.

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.

Theoretical analysis of a rolling-sliding elastohydrodynamic lubrication line contact with a subsurface inclusion

2019 ◽  
Vol 233 (8) ◽  
pp. 1197-1207
Author(s):  
Armando Félix Quiñonez ◽  
Guillermo E Morales Espejel
Keyword(s):  
Elastohydrodynamic Lubrication ◽  
Element Model ◽  
Von Mises Stress ◽  
Transient Effects ◽  
Mean Velocity ◽  
The Matrix ◽  
Soft Inclusion ◽  
The Mean ◽  
Von Mises ◽  
Fully Coupled

This work investigates the transient effects of a single subsurface inclusion over the pressure, film thickness, and von Mises stress in a line elastohydrodynamic lubrication contact. Results are obtained with a fully-coupled finite element model for either a stiff or a soft inclusion moving at the speed of the surface. Two cases analyzed consider the inclusion moving either at the same speed as the mean velocity of the lubricant or moving slower. Two additional cases investigate reducing either the size of the inclusion or its stiffness differential with respect to the matrix. It is shown that the well-known two-wave elastohydrodynamic lubrication mechanism induced by surface features is also applicable to the inclusions. Also, that the effects of the inclusion become weaker both when its size is reduced and when its stiffness approaches that of the matrix. A direct comparison with predictions by the semi-analytical model of Morales-Espejel et al. ( Proc IMechE, Part J: J Engineering Tribology 2017; 231) shows reasonable qualitative agreement. Quantitatively some differences are observed which, after accounting for the semi-analytical model's simplicity, physical agreement, and computational efficiency, may then be considered as reasonable for engineering applications.

scholarly journals PENERAPAN METODE MULTI ATTRIBUTE UTILITY THEORY (MAUT) DALAM PEMETAAN TINGKAT DAMPAK BENCANA BANJIR DI KABUPATEN BANTUL

Telematika ◽  
2020 ◽  
Vol 17 (1) ◽  
pp. 26
Author(s):  
Afif Irfan Abdurrahman ◽  
Bambang Yuwono ◽  
Yuli Fauziah
Keyword(s):  
Utility Theory ◽  
Matrix Multiplication ◽  
Flood Disaster ◽  
Accuracy Rate ◽  
Affected Area ◽  
A Value ◽  
Multi Attribute Utility Theory ◽  
The Matrix ◽  
The Difference ◽  
The Impact

Flood disaster is a dangerous disaster, an event that occurs due to overflow of water resulting in submerged land is called a flood disaster. Almost every year Bantul Regency is affected by floods due to high rainfall. The flood disaster that struck in Bantul Regency made the Bantul District Disaster Management Agency (BPBD) difficult to handle so that it needed a mapping of the level of the impact of the flood disaster to minimize the occurrence of floods and provide information to the public.This study will create a system to map the level of impact of floods in Bantul Regency with a decision support method namely Multi Attribute Utility Theory (MAUT). The MAUT method stage in determining the level of impact of flood disasters through the process of normalization and matrix multiplication. The method helps in determining the areas affected by floods, by managing the Indonesian Disaster Information Data (DIBI). The data managed is data on criteria for the death toll, lost victims, damage to houses, damage to public facilities, and damage to roads. Each criteria data has a value that can be used to determine the level of impact of a flood disaster. The stages for determining the level of impact of a disaster require a weighting calculation process. The results of the weighting process display the scoring value which has a value of 1 = low, 2 = moderate, 3 = high. To assist in determining the affected areas using the matrix normalization and multiplication process the process is the application of the Multi Attribute Utility Theory (MAUT) method.This study resulted in a mapping of the level of impact displayed on google maps. The map view shows the affected area points and the level of impact of the flood disaster in Bantul Regency. The mapping produced from the DIBI data in 2017 produced the highest affected area in the Imogiri sub-district. The results of testing the data can be concluded that the results of this study have an accuracy rate of 95% when compared with the results of the mapping previously carried out by BPBD Bantul Regency. The difference in the level of accuracy is because the criteria data used are not the same as the criteria data used by BPBD in Bantul Regency so that the accuracy rate is 95%.

Continuum damage mechanics-based analysis of creep–fatigue interaction behavior in a turbine rotor

2018 ◽  
Vol 28 (3) ◽  
pp. 455-477 ◽  
Author(s):  
WZ Wang ◽  
YZ Liu
Keyword(s):  
Damage Mechanics ◽  
Maximum Stress ◽  
Continuum Damage Mechanics ◽  
Turbine Rotor ◽  
Von Mises Stress ◽  
Temperature Phase ◽  
Continuum Damage ◽  
Interaction Behavior ◽  
Creep Fatigue ◽  
The Impact

The aim of this study is to analyze the creep–fatigue interaction behavior of a steam turbine rotor under idealized cyclic thermomechanical loading conditions. A Chaboche model-based material constitutive model is applied to simulate the multiaxial stress–strain behavior in the rotor. Influence of accumulated damage during the whole iterations on the creep–fatigue interaction behavior is described by continuum damage mechanics. Analysis of the temperature and stress variations during the startup phase reveals that the startup phase can be divided into a condensation phase, a high steam flux phase, and an elevated temperature phase and that thermal stress reaches its maximum value in the condensation phase. In addition, creep–fatigue interaction in the rotor leads to a gradual decrease in the maximum stress; furthermore, comparison of the von Mises stress displays that the impact of damage accumulation results in the shift of the location with the maximum stress. Investigation of creep–fatigue damage discloses that the total damage is concentrated on the steam inlet notch zone and the blade groove of the first and third stages.

SuperMeshing: A Deep Learning Method for Boosting Mesh Density in Numerical Computation Within 2D Domain

2021 ◽  
Author(s):  
Handing Xu ◽  
Zhenguo Nie ◽  
Qingfeng Xu ◽  
Xinjun Liu
Keyword(s):  
Numerical Computation ◽  
Spatial Resolution ◽  
Maximum Stress ◽  
Linear Mapping ◽  
Stress Fields ◽  
Von Mises Stress ◽  
Full Detail ◽  
Mesh Density ◽  
Novel Method ◽  
Von Mises

Abstract Due to the limit of mesh density, the improvement of the spatial resolution of numerical computation always leads to a decrease in computing efficiency. Aiming at this inability of numerical computation, we propose a novel method for boosting the mesh density in finite element method (FEM) within 2D domain. Based on the von Mises stress fields of 2D plane-strain problems computed by the FEM, this method utilizes a deep neural network named SuperMeshingNet to learn a non-linear mapping from low mesh-density to high mesh-density in stress fields, and realizes the improvement of numerical computation accuracy and efficiency simultaneously. We adopt residual dense blocks into our mesh-density boost model – SuperMeshingNet to extract abundant local features and enhance the prediction capacity. The results indicate that SuperMeshingNet is able to effectively increase the spatial resolution of the von Mises stress fields under the multiple scaling factors: 2X,4X,and8X. Compared with the targets, the relative error of SuperMeshingNet is 2.44%, which shows better performance than the interpolation methods. Besides, SuperMeshingNet reveals an astonishing strength in predicting the maximum stress value. We publicly share our work with full detail of implementation at https://github.com/zhenguonie/2021_SuperMeshing_2D_Plane_Strain.

Evaluation and Analysis of Different Types of Prosthetic Knee Joint Used by above Knee Amputee

2020 ◽  
Vol 398 ◽  
pp. 34-40 ◽  
Author(s):  
Fahad Mohanad Kadhim ◽  
Jumaa Salman Chiad ◽  
Maryam Abdul Salam Enad
Keyword(s):  
Gait Cycle ◽  
Reaction Force ◽  
Maximum Velocity ◽  
Knee Joints ◽  
Von Mises Stress ◽  
Prosthetic Knee ◽  
Prosthetic Limb ◽  
Left And Right ◽  
The Difference ◽  
Von Mises

Four prosthetic knee joints (polycentric knee weight activating-4bar and friction, extension assist controlled),(single axis knee weight activating and friction, internal extension assist controlled), (single axis knee weight activating-4bar and hydraulically, controlled) and (polycentric knee geometric locking-6bar, hydraulically controlled) for a trans-femoral patient were tested. The tests were conducted to find the maximum velocity as well as discussing the most comfortable prosthetic forthe patient and walking stability for these prosthetic knees by examining the gait cycle and measuring the ground reaction force (GRF), using force a plate device. Also, the interface pressure was measured between socket and stump muscles by using F-socket device to get the stress distribution during walking with a prosthetic knee. Results manifested that the polycentric knee geometric locking - 6bar, hydraulically controlled is the best because of the good homogenous distribution of GRF between the healthy and prosthetic limb, during which the difference between both the healthy and prosthetic limb is with the least value (4%).And, K4 gives the minimum value of differences in contact pressure between the left and right limb with a value of (24%), it alsoimparts the maximum symmetry between the left and right limb according to the gait cycle parameters.The best results of the interface pressures and kinovea velocity are achieved whenK4 is used with (132.4KPa, 0.71m/s), respectively. Finally, the polycentric knee geometric locking - 6bar, hydraulically controlled is the best according to the ANSYS results during which it yields the minimum values of Von-Mises stress with 14.24MPa and a maximum factor of safety of 3.11.

scholarly journals Tympanic Membrane Collagen Expression by Dynamically Cultured Human Mesenchymal Stromal Cell/Star-Branched Poly(ε-Caprolactone) Nonwoven Constructs

2020 ◽  
Vol 10 (9) ◽  
pp. 3043
Author(s):  
Stefania Moscato ◽  
Antonella Rocca ◽  
Delfo D’Alessandro ◽  
Dario Puppi ◽  
Vera Gramigna ◽  
...  
Keyword(s):  
Tympanic Membrane ◽  
Maximum Stress ◽  
Element Model ◽  
Von Mises Stress ◽  
Type I ◽  
Collagen Types ◽  
Collagen Expression ◽  
Polymerase Chain ◽  
Von Mises ◽  
Membrane Collagen

The tympanic membrane (TM) primes the sound transmission mechanism due to special fibrous layers mainly of collagens II, III, and IV as a product of TM fibroblasts, while type I is less represented. In this study, human mesenchymal stromal cells (hMSCs) were cultured on star-branched poly(ε-caprolactone) (*PCL)-based nonwovens using a TM bioreactor and proper differentiating factors to induce the expression of the TM collagen types. The cell cultures were carried out for one week under static and dynamic conditions. Reverse transcriptase-polymerase chain reaction (RT-PCR) and immunohistochemistry (IHC) were used to assess collagen expression. A Finite Element Model was applied to calculate the stress distribution on the scaffolds under dynamic culture. Nanohydroxyapatite (HA) was used as a filler to change density and tensile strength of *PCL scaffolds. In dynamically cultured *PCL constructs, fibroblast surface marker was overexpressed, and collagen type II was revealed via IHC. Collagen types I, III and IV were also detected. Von Mises stress maps showed that during the bioreactor motion, the maximum stress in *PCL was double that in HA/*PCL scaffolds. By using a *PCL nonwoven scaffold, with suitable physico-mechanical properties, an oscillatory culture, and proper differentiative factors, hMSCs were committed into fibroblast lineage-producing TM-like collagens.

Interfacial properties of all-polypropylene composites

e-Polymers ◽  
2010 ◽  
Vol 10 (1) ◽  
Author(s):  
Shadi Houshyar ◽  
Robert A. Shanks
Keyword(s):  
Optical Microscope ◽  
Processing Conditions ◽  
Polypropylene Composites ◽  
Melting Temperatures ◽  
Pull Out ◽  
Physico Chemical ◽  
Microbond Test ◽  
The Matrix ◽  
The Difference ◽  
Poly Propylene

AbstractPreparation and characterization of novel composites, consisting of polypropylene (PP) fibres in a random poly(propylene-co-ethylene) (PPE) matrix, were investigated. These composites possess unique properties, due to chemical compatibility of the two polymers allowing creation of strong physico-chemical interactions and strong interfacial bonds. The difference between the melting temperatures of PP fibre and PPE was exploited in order to establish processing conditions for the composites. Suitable conditions were chosen so that the matrix was a liquid, to ensure good wetting and impregnation of the fibres, though the temperature must not be high enough to melt the fibres. The morphology of the composites was investigated using optical and scanning electron microscopy. Optical microscope images showed that transcrystallization of the matrix was observed on PP fibre surfaces. SEM photographs displayed a thin layer of matrix on the reinforcement, attributed to good impregnation and wetting of the fibres. Adhesion between PPE matrix and PP fibres was characterized using a microbond test inspired by a fibre pull-out technique. The results showed that adhesion was appreciably increased when PP fibres were used instead of glass fibres in the matrix. Nevertheless, thermal processing conditions of the composites caused reduction in mechanical behaviour of the reinforcement.

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.

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