Test Methods for Axial Compressive Force Pulse (Rapid) Testing of Deep Foundations

2010 ◽  
Author(s):  
Keyword(s):  
Compressive Force ◽  
Test Methods ◽  
Deep Foundations ◽  
Rapid Testing ◽  
Axial Compressive Force ◽  
Force Pulse

Effect of Coulomb Damping on Buckling of a Simply Supported Beam

1999 ◽  
Author(s):  
H. Yabuno ◽  
R. Oowada ◽  
N. Aoshima
Keyword(s):  
Compressive Force ◽  
Pitchfork Bifurcation ◽  
Steady States ◽  
Initial Condition ◽  
Axial Compressive Force ◽  
Simply Supported Beam ◽  
Simply Supported ◽  
Coulomb Damping ◽  
Buckling Behavior ◽  
Equilibrium Region

Abstract The present work describes a significant influence of a slight Coulomb damping on buckling of the simply supported beam subjected to an axial compressive force. Coulomb damping in the supporting points produces equilibrium regions around the well-known stable and unstable steady states under the pitchfork bifurcation which are analytically obtained in no consideration of the effect of Coulomb damping. After the transient response, the beam can stop any states in the equilibrium region, which becomes wider in the vicinity of the bifurcation point, depending on the initial condition. Also, the imperfection due to gravity is considered and it is theoretically shown that the equilibrium region is connected in the case when the imperfection due to gravity is relatively small comparing with the effect of the Coulomb damping, while the steady states under the pitchfork bifurcation in no consideration of the effect of Coulomb damping are necessarily disconnected by imperfection. Experimental results confirm the theoretically predicted effect of Coulomb damping in the supporting point on the buckling behavior of the beam.

Biomechanical Study of Lumbar Spine (L2-L4) Using Hybrid Stabilization Device - A Finite Element Analysis

2020 ◽  
Vol 10 (1) ◽  
pp. 20-32 ◽  
Author(s):  
Pushpdant Jain ◽  
Mohammed Rajik Khan
Keyword(s):  
Finite Element ◽  
Compressive Force ◽  
Element Model ◽  
Biomechanical Study ◽  
Bottom Surface ◽  
Element Analysis ◽  
Axial Compressive Force ◽  
Hybrid Stabilization ◽  
Flexion Extension ◽  
Lumbar Segment

Spinal instrumentations have been designed to alleviate lower back pain and stabilize the spinal segments. The present work aims to evaluate the biomechanical effect of the proposed Hybrid Stabilization Device (HSD). Non-linear finite element model of lumbar segment L2-L4 were developed to compare the intact spine (IS) with rigid implant (RI) and hybrid stabilization device. To restrict all directional motion vertebra L4 bottom surface were kept fixed and axial compressive force of 500N with a moment of 10Nm were applied to the top surface of L2 vertebrae. The results of range of motion (ROM), intervertebral disc (IVD) pressure and strains for IVD-23 and IVD-34 were determined for flexion, extension, lateral bending and axial twist. Results demonstrated that ROM of HSD model is higher than RI and lower as compared to IS model. The predicted biomechanical parameters of the present work may be considered before clinical implementations of any implants.

scholarly journals Biomechanical Evaluation of Suture Button Spread with and without Deltoid Repair in Combined Syndesmosis and Deltoid Injury

2020 ◽  
Vol 5 (4) ◽  
pp. 2473011420S0031
Author(s):  
Brian Lau ◽  
Hunter Storaci ◽  
Kaysie Tam ◽  
Cara Lai ◽  
Brett P. Salazar ◽  
...  
Keyword(s):  
Compressive Force ◽  
Joint Line ◽  
Joint Surface ◽  
Axial Compressive Force ◽  
Ankle Motion ◽  
Posterior Displacement ◽  
Intact State ◽  
Suture Button ◽  
Syndesmosis Injury ◽  
Injury And Repair

Category: Sports; Basic Sciences/Biologics Introduction/Purpose: Syndesmosis injuries are common and frequently occur with deltoid injuries but optimal repair remains controversial. Prior biomechanical studies have demonstrated that 1 and 2 suture buttons are equivalent to screw fixation and that parallel or divergent suture buttons are equivalent to single suture button. Prior studies, however, created constructs with suture buttons within 1cm from each other (2-3cm from joint surface). Additionally, the role of deltoid injury and repair have not been evaluated in conjunction with syndesmosis injury and repair. The purpose of this study was to biomechanically compare a narrow vs spread 2-suture button construct with and without a deltoid repair. Methods: Four matched lower leg specimens (8 total specimens) aged mean 60.2 years (range 57-66 years; 6 females and 2 males; mean BMI 21.1) were tested. Ankle motion under cyclic loading was measured in multiple planes: first in the intact state, following simulated syndesmosis and deltoid injury, then following fixation with 1 of 2 randomly assigned constructs: 2 parallel suture buttons at 2 and 3cm from joint line (narrow); and 2 parallel suture buttons at 1 and 4cm from joint line (spread), and then finally following a deltoid repair with each construct. Each state was tested at a constant 750 N axial compressive force and 5N internal/external torque. Rotation position (degrees) and anterior-posterior displacement (mm) were collected throughout the testing to characterize relative spatial relationships of the tibiofibular articulation using 3D video capture technology. Results: Narrow and spread 2-suture button constructs improved rotation and translation compared to cut state (p<0.05) but not to intact state (p>0.05). There were no significant differences in rotation or translation between Narrow and Spread constructs (p>0.05). The addition of a deltoid repair did not improve rotation or translation compared to syndesmosis repair with either construct alone (p>0.05). Conclusion: The preliminary results of this study suggest that constructs with suture button placed close together or spread apart during fixation of combined syndesmosis and deltoid injury could improve rotation and translation equally. Additionally, in a combined syndesmosis and deltoid injury, the addition of a deltoid repair to a syndesmosis repair did not strengthen the construct. These findings suggest that repair of syndesmosis alone may be sufficient in combined syndesmosis and deltoid injuries. Additional matched samples will be tested to validate preliminary findings.

Effects of Vertebral Body Changes on Cervical Spine Load Sharing

2002 ◽  
Author(s):  
Jiangyue Zhang ◽  
Narayan Yoganandan ◽  
Frank A. Pintar
Keyword(s):  
Cervical Spine ◽  
Young’S Modulus ◽  
Vertebral Body ◽  
Modulus Of Elasticity ◽  
Young's Modulus ◽  
Compressive Force ◽  
Axial Compressive Force ◽  
Inferior Surface ◽  
Biomechanical Behavior ◽  
Young’S Modulus Of Elasticity

The objective of the study was to determine the effects of changes in the Young’s modulus of elasticity of the cancellous bone that occur due to the ageing process on the biomechanical behavior of the cervical spine. An anatomically accurate three-dimensional (3-D) nonlinear finite element model of the C4-C5-C6 cervical spinal unit was used. The inferior surface of the C6 vertebrae was fixed in all degrees of freedom, and external loads were applied to the top surface of the C4 vertebra. The model was exercised under an axial compressive force of 754 N. In addition, flexion and extension bending moments of 3.44 Nm were applied individually to the model. The effects of ageing on bone strength were simulated by decreasing the Young’s modulus of elasticity from 100 MPa in the healthy spine to 40 MPa in the degenerated spine. The degenerated spine was found to be more flexible than the healthy spine. In addition, the degenerated spine responded with increased forces in the outer anterior and posterior regions of the vertebral body. Furthermore, forces in the facet joints increased in the degenerated spine. In contrast, the middle region of the disc showed decreased forces. These increases in the forces leading to stress risers may explain the occurrence of osteophytes in the spine with age.

Bonding Mechanism of Horizontal Construction Joints

2011 ◽  
Vol 368-373 ◽  
pp. 1264-1267
Author(s):  
Chun Ming Wei ◽  
Hui Su ◽  
Qiang Zhao ◽  
Chun Li Bi
Keyword(s):  
Compressive Force ◽  
Shear Capacity ◽  
Joint Interface ◽  
Axial Compressive Force ◽  
Failure Characteristics ◽  
Displacement Ductility ◽  
Construction Joint ◽  
Construction Joints ◽  
Concrete Placement

The quality of construction joint is significantly influenced by the precision in the concrete placement. In order to obtain the mechanical properties of horizontal construction joints surface, a comprehensive research was conducted. The research focused on the tensile capacity and seismic behavior of construction joints surface. According the tests failure characteristics, four kinds of cracking model of construction joints zone were formed. Test results indicated that bond materials could increase displacement ductility more than 10％～30％. And the clamping action provided by bond materials was so good that failure didn’t occur at the construction joint itself, but in the concrete adjacent to it. Axial compressive force is advantageous for the shear capacity of construction joint interface.

Finite Element Modeling of van der Waals Interaction for Elastic Stability of Multi-Walled Carbon Nanotubes

2008 ◽  
Vol 55-57 ◽  
pp. 525-528 ◽  
Author(s):  
Chawis Thongyothee ◽  
Somchai Chucheepsakul
Keyword(s):  
Carbon Nanotubes ◽  
Finite Element ◽  
Van Der Waals ◽  
Compressive Force ◽  
Covalent Bond ◽  
Van Der Waals Force ◽  
Tube Length ◽  
Axial Compressive Force ◽  
Multi Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes

The purpose of this study is to assess the effect of van der Waals interactions within multi-walled carbon nanotubes with the three dimensional finite element models. The elastic buckling behaviors of nanotubes are treated under axial compressive force acting on open both ends of nanotubes and considered with various boundary conditions. The analysis is based on the assumptions that the covalent bond of each wall is represented by an elastic beam element while the van der Waals force of adjacent walls are represented by a nonlinear truss element following the Lennard-Jones “6-12” theory. The models of double-walled carbon nanotubes are used to explain the characteristic of multi-walled carbon nanotubes and then results compared with the column theory. The results show that the critical load of nanotubes depends on atomic arrangement, tube length, and number of walls, while the van der Waals force has a small effect on the buckling load for multi-walled carbon nanotubes.

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