COHESIVE FINITE ELEMENT SIMULATIONS OF CONTRACTION AND SHAPE EFFECTS ON CELL DE-ADHESION

2017 ◽  
Vol 17 (06) ◽  
pp. 1750091
Author(s):  
MARGARITA PETROVA ◽  
ZHIWEN GAO ◽  
YAN LIU ◽  
YANFEI GAO ◽  
WEI HE
Keyword(s):  
Finite Element ◽  
Shear Stress ◽  
Stress Concentration ◽  
Critical Shear Stress ◽  
Finite Element Simulations ◽  
Additional Stress ◽  
Initial Stiffness ◽  
Mode Iii ◽  
Cohesive Interface ◽  
Cell Shapes

Cohesive-interface-based finite element simulations were conducted to investigate the critical shear stress required for cell de-adhesion from extracellular substrates. The interface ligand–receptor bonds are modeled by a cohesive interface model with initial stiffness, interface strength, and fracture energy as the governing parameters. The ratio of the cell modulus to the interface stiffness defines a length scale. If this length is much less than the contact size, the de-adhesion process can be modeled by the linear elastic fracture mechanics, while the opposite limit leads to the concurrent sliding of the cell or, equivalently, debonding of all the interface ligand–receptor pairs. Since it generates additional shear-stress concentration along the interface, cell contraction generally reduces the critical de-adhesion stress. Cell de-adhesion is more prone to take place for three-dimensional irregular cell shapes because of the much easier failure in the anti-plane Mode III shear, as well as the additional stress concentration in these geometric irregularities.

scholarly journals Modeling of contact stress and tool-based frictional forces considering edge effect through material separation exploration

2021 ◽  
Author(s):  
Weiwei Zhang ◽  
Jian Weng ◽  
Kejia Zhuang ◽  
Cheng Hu ◽  
Xing Dai ◽  
...  
Keyword(s):  
Finite Element ◽  
Shear Stress ◽  
Contact Stress ◽  
Finite Element Simulations ◽  
Cutting Edge ◽  
Contact Model ◽  
Feature Points ◽  
Normal Contact ◽  
Frictional Forces ◽  
Material Separation

Abstract Cutting tools with round edge can enhance the performance of machining difficult-to-machine materials, while the complex contact mechanism related to micro cutting edge limits the deeper understanding of cutting mechanics. Material separation, which is associate to plough mechanism with formation of dead metal zone (DMZ), also requires the analysis of contact behavior. This study develops a contact model along the round edge together with the illustration of DMZ, with three contact feature points defined to explain the contact situation between workpiece and cutting edge. Among these feature points, two separation points related to DMZ classify the sliding and sticking region considering the dual-zone approach. The stagnation point is the zero shear stress point where a sudden change in shear stress direction happens. Besides, the parabolic stress model obtained from finite element simulations is established to define the normal contact distribution along the round edge. In this basis, the tool-based frictional forces are determined and two contact force components are classified for different contact regions. The proposed contact feature points and contact stress are validated through illustration with finite element simulations. Besides, orthogonal cutting tests ensure the practicality and accuracy of the proposed contact model and predicted cutting forces.

Relaxation of Stress Concentration of a Crack by Stop Drilling Holes and Additional Holes and Its Practical Prediction

2010 ◽  
Vol 452-453 ◽  
pp. 705-708 ◽  
Author(s):  
Tatsujiro Miyazaki
Keyword(s):  
Finite Element ◽  
Fatigue Life ◽  
Stress Concentration ◽  
Fatigue Damage ◽  
Crack Tip ◽  
Relaxation Effect ◽  
Finite Element Simulations ◽  
Repair Method ◽  
Center Crack ◽  
Drilling Hole

It is well known that a stress concentration of a crack can be relaxed by drilling a hole at the crack tip. The repair method is called a stop drilling procedure and often used to repair aircrafts, machines and so on. Then, when two additional holes are drilled near the stop drilling hole so as to face each other symmetrically, the stress concentration of the stop drilling hole can be relaxed further, and a fatigue life is extended. However, the size and the location of the additional hole suitable for repairing the fatigue damage are not clarified yet. In this paper, finite element simulations were performed on various plates containing the small center crack at which the stop drilling holes and the additional holes were drilled, and influences of the additional hole on the relaxation effect of the stress concentration of the stop drilling hole were investigated. Then, the size and the location of such additional hole that the stress concentration of the stop drilling hole is minimized were examined.

scholarly journals Structural Analysis of an Aluminum Multihull

2015 ◽  
Vol 8 (17) ◽  
pp. 87
Author(s):  
David Fuentes ◽  
Marcos Salas ◽  
Gonzalo Tampier ◽  
Claudio Troncoso
Keyword(s):  
Finite Element ◽  
Stress Concentration ◽  
Structural Analysis ◽  
Finite Element Model ◽  
Conceptual Design ◽  
High Performance ◽  
Element Model ◽  
Additional Stress ◽  
Passenger Transport ◽  
Research Project

Structural analysis of a multihull is relatively complex since the connecting structure introduces additional stress than those typical of a monohull. The aluminum trimaran presented in this work was designed within the framework of the research project “Conceptual Design of a High-performance Vessel for Passenger Transport in Chile’s Austral Zone”. The trimaran was structurally measured using the regulations of classification societies Germanischer Lloyd, Det Norske Veritas y LloydÅLs Register. For the scantlings obtained with each regulation a Finite Element Model was created and the structural analysis for the slamming and splitting moment events was made. The results were analyzed and the stress concentration zones were determined to compare them with admissible stresses and conclude whether the structural sizing adequately and safely responds to the design stresses.

scholarly journals Correlation of Stress Concentration Factors for T-Welded Connections – Finite Element Simulations and Fatigue Behavior

2017 ◽  
Vol 22 (2) ◽  
pp. 194-206 ◽  
Author(s):  
Gerardo Terán Méndez ◽  
Rubén Cuamatzi-Meléndez ◽  
Apolinar Albiter Hernández ◽  
Selene I. Capula-Colindres ◽  
Daniel Angeles-Herrera ◽  
...  
Keyword(s):  
Finite Element ◽  
Stress Concentration ◽  
Fatigue Behavior ◽  
Finite Element Simulations ◽  
Concentration Factors ◽  
Stress Concentration Factors

A 3D Finite Element Study of Fatigue Life Dispersion in Rolling Line Contacts

2011 ◽  
Vol 133 (4) ◽  
Author(s):  
Nick Weinzapfel ◽  
Farshid Sadeghi ◽  
Vasilios Bakolas ◽  
Alexander Liebel
Keyword(s):  
Finite Element ◽  
Shear Stress ◽  
Material Properties ◽  
Rolling Contact Fatigue ◽  
Contact Fatigue ◽  
Critical Shear Stress ◽  
Rolling Contact ◽  
Shear Stresses ◽  
Rolling Element Bearings ◽  
Rolling Element

Rolling contact fatigue of rolling element bearings is a statistical phenomenon that is strongly affected by the heterogeneous nature of the material microstructure. Heterogeneity in the microstructure is accompanied by randomly distributed weak points in the material that lead to scatter in the fatigue lives of an otherwise identical lot of rolling element bearings. Many life models for rolling contact fatigue are empirical and rely upon correlation with fatigue test data to characterize the dispersion of fatigue lives. Recently developed computational models of rolling contact fatigue bypass this requirement by explicitly considering the microstructure as a source of the variability. This work utilizes a similar approach but extends the analysis into a 3D framework. The bearing steel microstructure is modeled as randomly generated Voronoi tessellations wherein each cell represents a material grain and the boundaries between them constitute the weak planes in the material. Fatigue cracks initiate on the weak planes where oscillating shear stresses are the strongest. Finite element analysis is performed to determine the magnitude of the critical shear stress range and the depth where it occurs. These quantities exhibit random variation due to the microstructure topology which in turn results in scatter in the predicted fatigue lives. The model is used to assess the influence of (1) topological randomness in the microstructure, (2) heterogeneity in the distribution of material properties, and (3) the presence of inherent material flaws on relative fatigue lives. Neither topological randomness nor heterogeneous material properties alone account for the dispersion seen in actual bearing fatigue tests. However, a combination of both or the consideration of material flaws brings the model’s predictions within empirically observed bounds. Examination of the critical shear stress ranges with respect to the grain boundaries where they occur reveals the orientation of weak planes most prone to failure in a three-dimensional sense that was not possible with previous models.

A Study on the Tensile Strength of the Layer Splice Laminates

2011 ◽  
Vol 399-401 ◽  
pp. 351-354
Author(s):  
Ling Wang ◽  
Pu Rong Jia ◽  
Gui Qiong Jiao
Keyword(s):  
Finite Element ◽  
Tensile Strength ◽  
Shear Stress ◽  
Stress Concentration ◽  
Experimental Tests ◽  
Tensile Failure ◽  
Resin Matrix ◽  
Laminar Shear Stress ◽  
Element Analysis ◽  
Joint Location

The tensile strength of carbon fiber reinforced resin matrix layer splice laminate was studied. Three specimens (M1.M2.M3) were cut from laminates with different joint location and the number of layer splice. Load schemes were performed and typical load-displacement curves of three specimens were recorded. The result shows that the joint location has seriously effect on the tensile strength and modulus of specimens. The tensile strength of M2 is obviously lower than that of M1 and M3. Furthermore finite element ABAQUS6.5 was also used to simulate the course of experimental test. The result shows that shear stress concentration occurs on the joint of model. The shear stress on the model M1 and M2 has the similar trend and concentrates in the middle of the joint area. And on the model of M3 the shear stress has a completely different trend from the M1 and M2 model. On the M2 the shear stress concentration is slightly higher than the other two. It indicates that the tensile strength of M2 is the lowest among the three models. So, the inter-laminar shear stress is the major factor leading tensile failure. The experimental tests are consistent with the finite element analysis.

Numerical Analysis of Interlaminar Stress Distributions around Hole in Thermoplastic Laminate

2011 ◽  
Vol 368-373 ◽  
pp. 1543-1546
Author(s):  
Guo Hua Zhao ◽  
Qing Lian Shu ◽  
Bo Sheng Huang
Keyword(s):  
Finite Element ◽  
Shear Stress ◽  
Stress Concentration ◽  
Numerical Models ◽  
Finite Element Code ◽  
Stress Distributions ◽  
Interlaminar Stress ◽  
Hole Edge ◽  
Interlaminar Shear Stress ◽  
Interlaminar Shear

This paper investigates the interlaminar stress distributions at hole edge of notched thermoplastic laminates. Two numerical models of AS4/PEEK laminates with configuration of [±25]S4 and [0/±45/90]2S were built and studied by finite element code ANSYS. The results show: (1) The angle-ply configuration ([±25]S4) may cause more severe concentration of interlaminar shear stress at hole edge; (2) the quasi-isotropic configuration ([0/±45/90]2S) can lessen the stress concentration at hole edge.

Finite Element Analysis of Tire/Rim Interface Forces Under Braking and Cornering Loads

1992 ◽  
Vol 20 (2) ◽  
pp. 83-105 ◽  
Author(s):  
J. P. Jeusette ◽  
M. Theves
Keyword(s):  
Finite Element ◽  
Shear Stress ◽  
Contact Pressure ◽  
Element Model ◽  
Shear Stresses ◽  
Detailed Knowledge ◽  
Stress Distributions ◽  
Element Analysis ◽  
Plane Shear ◽  
Normal Contact

Abstract During vehicle braking and cornering, the tire's footprint region may see high normal contact pressures and in-plane shear stresses. The corresponding resultant forces and moments are transferred to the wheel. The optimal design of the tire bead area and the wheel requires a detailed knowledge of the contact pressure and shear stress distributions at the tire/rim interface. In this study, the forces and moments obtained from the simulation of a vehicle in stationary braking/cornering conditions are applied to a quasi-static braking/cornering tire finite element model. Detailed contact pressure and shear stress distributions at the tire/rim interface are computed for heavy braking and cornering maneuvers.

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