A Model of Force Transmission in the Tibio-Femoral Contact Incorporating Fluid and Mixtures

1991 ◽  
Vol 205 (4) ◽  
pp. 233-241 ◽  
Author(s):  
G J M A Schreppers ◽  
A A H J Sauren ◽  
A Huson
Keyword(s):  
Load Distribution ◽  
Major Part ◽  
Mixture Theory ◽  
Element Model ◽  
Step Change ◽  
Solid Modelling ◽  
Force Transmission ◽  
Relaxation Period ◽  
Cartilage Layer ◽  
Spherical Indentor

An axisymmetric finite element model is formulated which comprises a rigid spherical indentor, a meniscal ring and an articular cartilage layer, both considered as mixture materials which are interacting with an ideal fluid sub-system. From parameter studies it is concluded that the application of the mixture theory in comparison with solid modelling only leads to significant effects when the outer surfaces of the components are not sealed. The load distribution appears to change enormously during relaxation of the models. Initially the largest fraction of the load is borne by the fluid in the cavity, while at the end, when the system has reached its final configuration, the meniscal ring bears the major part of the load. Further, the length of the relaxation period appears to depend on the magnitude of the step change of the load. Finally, the curvature of the spherical indentor appears to have significant effects on the loading of the meniscal ring, only immediately after the step changes of load are applied, and these effects disappear as soon as the fluid starts to exude from the models.

scholarly journals Load transfer through the radiocarpal joint and the effects of partial wrist arthrodesis on carpal bone behaviour: a finite element study

2012 ◽  
Vol 37 (9) ◽  
pp. 871-878 ◽  
Author(s):  
M. K. Gíslason ◽  
B. Stansfield ◽  
M. Bransby-Zachary ◽  
T. Hems ◽  
D. H. Nash
Keyword(s):  
Finite Element ◽  
Load Transfer ◽  
Element Model ◽  
Carpal Bone ◽  
Force Transmission ◽  
Wrist Arthrodesis ◽  
Partial Arthrodesis ◽  
Radiocarpal Joint ◽  
Radioscapholunate Fusion ◽  
Operative Planning

A finite element model of the wrist was developed to simulate mechanical changes that occur after surgery of the wrist. After partial arthrodesis, the wrist will experience altered force transmission during loading. Three different types of partial arthrodesis were investigated — radiolunate, radioscaphoid, and radioscapholunate — and compared with the healthy untreated wrist. The results showed that the compressive forces on the radiocarpal joint decreased compared with the untreated wrist with both radiolunate and radioscaphoid fusions. The load transmission through the midcarpal joints varied depending on arthrodesis type. The forces in the extrinsic ligaments decreased with the fusion, most noticeably in the dorsal radiotriquetral ligament, but increased in the dorsal scaphotriquetral ligament. From the results of the study it can be concluded that the radioscapholunate fusion shows the most biomechanically similar behaviour out of the three fusion types compared with the healthy wrist. The modelling described in this paper may be a useful approach to pre-operative planning in wrist surgery.

Operational Risk Assessment of Wind Turbine Structures Using Probabilistic Analysis of Aerodynamically Induced Vibrations

2011 ◽  
Author(s):  
Antonio Velazquez ◽  
R. Andrew Swartz
Keyword(s):  
Risk Assessment ◽  
Wind Turbine ◽  
Numerical Solution ◽  
Vortex Shedding ◽  
Element Model ◽  
Aerodynamic Performance ◽  
Operating Conditions ◽  
Force Transmission ◽  
Resistance Risk ◽  
Structural Resistance

The study of efficiency and safety for wind turbine structures under variable operating conditions is increasingly important for wind turbine design. Optimum aerodynamic performance of a wind turbine demands that serviceability effects and ultimate strength loads remain under safety design limits. From the perspective of wind turbine efficiency, variations in wind speed causes bluffing effects and vortex shedding that lead to vibration intensities in the longitudinal and transversal direction that can negatively impact aerodynamic performance of the turbine. From the perspective of wind turbine safety, variations in loading may lead to transient internal loads that threaten the safety of the structure. Inertial effects and asynchronous delays on rotational-force transmission may generate similar hazards. Monitoring and controlling displacement limits and load demands at critical tower locations can improve the efficiency of wind power generation, not to mention the structural performance of the turbine from both a strength and serviceability point of view. In this study, a probabilistic monitoring approach is developed to measure the response of the combined tower/nacelle/blade system to stochastic loading, estimate peak demand, and compare that demand to building code-derived estimates of structural resistance. Risk assessment is performed for the effects of along and across-wind forces in a framework of quantitative risk analysis with the goal of developing a near real-time estimate of structural risk that may be used to monitor safety and serviceability of the structure as well as regulate the aggressiveness of the controller that commands the blade angle of attack. To accomplish this goal, a numerical simulation of the aerodynamic performance of a wind turbine (including blades, the nacelle and the tower) is analyzed to study the interaction between the structural system and incoming flow. A model based on distributed-stationary random wind load profile for the combined along-wind and across-wind responses is implemented in Matlab to simulate full aero-elastic dynamic analysis to simulate tower with nacelle, hub, rotor and tower substructures. Self-weight, rotational, and axial effects of the blades, as well as lateral resistance of substructure elements are incorporated in the finite element model, including vortex-shedding effects on the wake zone. Reliability on the numerical solution is inspected on the tower structure by comparing the numerical solution with established experimental-analytical procedures.

Multiphasic Finite Element Analysis of Physical Signals and Solute Transport in the Human Intervertebral Disc

2004 ◽  
Author(s):  
Hai Yao ◽  
Wei Yong Gu
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Soft Tissue ◽  
Intervertebral Disc ◽  
Mixture Theory ◽  
Element Model ◽  
Tissue Composition ◽  
Element Analysis ◽  
3D Finite Element ◽  
Disc Nutrition

A 3D finite element model for charged hydrated soft tissue containing charged/uncharged solutes was developed based on the multi-phasic mechano-electrochemical mixture theory [1–2]. This model was applied to analyze the mechanical, chemical and electrical signals within the human intervertebral disc under mechanical loading. The effects of tissue composition and material property on the physical signals and the transport of fluid, ions and nutrients were investigated. This study is important for understanding disc biomechanics, disc nutrition and disc mechanobiology.

Tooth Root Stresses of Helical Gear Pairs With Unequal and Offset Face Widths

2011 ◽  
Author(s):  
Carlos H. Wink
Keyword(s):  
Load Distribution ◽  
Element Model ◽  
Helical Gear ◽  
The Other ◽  
Gear Pair ◽  
Tooth Root ◽  
Pair Member ◽  
Face Width ◽  
The Face ◽  
Root Stress

In this study, tooth root stresses of helical gear pairs with different combinations of face width increase and offsets were analyzed. Contact face width was kept constant. The variables studied were face width and gear faces offset. The well-known LDP – Load Distribution Program was used to calculate tooth root stresses using a finite element model. The results presented show that the face width increase and offset have a significant influence on tooth root stresses. In some cases, increasing face width of one gear pair member resulted in significant increase of tooth root stress of the other member. For gear pairs with unequal and offset face widths, tooth root stresses were mostly affected when face widths were increased to the same direction of the contact line travel direction.

Lifting Technique of Composite Bucket Foundation for Offshore Wind Turbines

2020 ◽  
Author(s):  
Hongyan Ding ◽  
Zuntao Feng ◽  
Puyang Zhang ◽  
Conghuan Le
Keyword(s):  
Finite Element ◽  
Prestressed Concrete ◽  
Large Scale ◽  
Element Model ◽  
Offshore Wind ◽  
Force Transmission ◽  
Element Analysis ◽  
Bucket Foundation ◽  
Transition Section ◽  
Section Structure

Abstract The onshore pre-fabrication technology for composite bucket foundations takes “prefabrication-assembly-lifting” as the core concept. The practice of pre-fabrication of upper and lower structures is prefabricated respectively. In the research of hoisting engineering technology, combined with the structural form and construction requirements of composite bucket foundation, the assembly scheme of the upper prestressed concrete transition section and the lower steel bucket and the hoisting scheme of integral foundation with compartments were designed. The finite element model in the lifting process of composite bucket foundation was established by the large-scale general finite element analysis software ABAQUS. For the optimization analysis of the lifting point arrangement during hoisting process, the number, position and arrangement form of lifting points are simulated and analyzed. The results show that the maximum value of the principal stress of the concrete transition section structure appears in the assembly stage with the lower steel bucket, and the structure checking calculation should be carried out as the most unfavorable lifting condition in construction; the peak point of structural stress is at the junction of girder and secondary beams and inner ring beams of concrete roof, which belongs to the weak position of force transmission. In construction, it should be paid attention to as the key part of monitoring to ensure composite bucket foundation is under reasonable stress and the stability in the lifting process. The research results can provide guidance and reference for the future batch production and standardization production construction for composite bucket foundations.

Research on the Arc-Teeth Synchronous Belt's Tooth Load Distribution Caused by the Machining Error

2014 ◽  
Vol 915-916 ◽  
pp. 248-251
Author(s):  
Yao Chen Shi ◽  
Zhan Guo Li ◽  
Hao Li
Keyword(s):  
Load Distribution ◽  
3D Model ◽  
Element Model ◽  
Transmission Performance ◽  
Machining Error ◽  
Machining Errors ◽  
Multibody Dynamic ◽  
Useful Life ◽  
Dynamic Software ◽  
The Finite Element Model

This paper aimed at the machining error of the arc-teeth synchronous belts tooth ,the 3D model was established with CATIA ,the finite element model of belt was established by HYPERMESH ,and using the multibody dynamic software RECURDYN, the models with different machining errors were simulated by rigid-flexible coupling technology. Systematically studied the changing rule of the wedged stress and the contact stress under the influence of the machining error. So it has certain value to enhance the loading capacity, transmission performance and useful life.

scholarly journals Experimental and Numerical Investigations of a Novel Laser Impact Liquid Flexible Microforming Process

Metals ◽  
2018 ◽  
Vol 8 (8) ◽  
pp. 599 ◽  
Author(s):  
Fei Liu ◽  
Huixia Liu ◽  
Chenkun Jiang ◽  
Youjuan Ma ◽  
Xiao Wang
Keyword(s):  
Numerical Simulation ◽  
Laser Energy ◽  
Pure Copper ◽  
Three Dimensional ◽  
Element Model ◽  
Force Transmission ◽  
Large Area ◽  
Laser Impact ◽  
Metallic Foils

A novel high strain rate microforming technique, laser impact liquid flexible embossing (LILFE), which uses laser induced shock waves as an energy source, and liquid as a force transmission medium, is proposed by this paper in order to emboss three-dimensional large area micro arrays on metallic foils and to overcome some of the defects of laser direct shock microembossing technology. The influences of laser energy and workpiece thickness on the deformation characteristics of the pure copper foils with the LILFE process were investigated through experiments and numerical simulation. A finite element model was built to further understand the typical stages of deformation, and the results of the numerical simulation are consistent with those achieved from the experiments. The experimental and simulation results show that the forming accuracy and depth of the embossed parts increases with the increase in laser energy and decrease in workpiece thickness. The thickness thinning rate of the embossed parts increases with the decrease of the workpiece thickness, and the severest thickness thinning occurs at the bar corner region. The experimental results also show that the LILFE process can protect the workpiece surface from being ablated and damaged, and can ensure the surface quality of the formed parts. Besides, the numerical simulation studies reveal the plastic strain distribution of embossed microfeatures under different laser energy.

scholarly journals Thermo-mechanical coupling–based finite element analysis of the load distribution of planetary roller screw mechanism

2018 ◽  
Vol 10 (6) ◽  
pp. 168781401877525 ◽  
Author(s):  
Shangjun Ma ◽  
Chenhui Zhang ◽  
Tao Zhang ◽  
Geng Liu ◽  
Shumin Liu
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Load Distribution ◽  
Three Dimensional ◽  
Theoretical Models ◽  
Element Model ◽  
Element Analysis ◽  
Mechanical Coupling ◽  
Roller Screw ◽  
Screw Mechanism

In this article, 3D or three-dimensional finite element analysis is used to simulate and evaluate the load distribution characteristics of a planetary roller screw mechanism under thermo-mechanical coupling. The finite element model takes into account the installation modes of the planetary roller screw mechanism, which is verified by comparison with theoretical models for a certain load magnitude in four installation modes. In addition, the effects of the installation mode, load magnitude, and temperature condition on the load distribution are also systematically analyzed. The numerical results reveal a phenomenon of threads separating from the meshing, which indicates that the influence of thermo-mechanical coupling on the load distribution cannot be ignored. Furthermore, the influence of the installation mode on the screw–roller interface is larger than that on the nut–roller interface. Compared with the screw–roller interface, the temperature difference is one of the main conditions affecting the load distribution of the planetary roller screw mechanism and has a significant effect on the nut–roller interface. In addition, the influences of the screw rotational speed and the load magnitude on the load distribution on the screw–roller interface are larger than those on the nut–roller interface for the four installation modes.

Design of Four Contact-Point Slewing Bearing With a New Load Distribution Procedure to Account for Structural Stiffness

2010 ◽  
Vol 132 (2) ◽  
Author(s):  
Mireia Olave ◽  
Xabier Sagartzazu ◽  
Jorge Damian ◽  
Alberto Serna
Keyword(s):  
Load Distribution ◽  
Contact Point ◽  
Element Model ◽  
Contact Forces ◽  
Elastic Model ◽  
Slewing Bearing ◽  
Extreme Loads ◽  
Highly Nonlinear ◽  
Rolling Elements ◽  
Bearing Rings

This paper proposes a procedure for obtaining the load distribution in a four contact-point slewing bearing considering the effect of the structure’s elasticity. The uneven stiffness of the rings and the supporting structures creates a variation with respect to the results obtained with a rigid model. It is necessary to evaluate the effect of the elasticity on the increase in the contact forces in order to be able to design the slewing bearing and the structures involved in the connection. Depending on the shape of the structures, the contact force value obtained on the most loaded rolling element is different. The evaluation of this maximum force at extreme loads is essential to design the structures joined to the bearing rings. The new elastic model presented in this paper is highly nonlinear so iterative loops are needed in order to obtain a satisfactory solution. At the same time a finite element model (FEM) has been created for the global model, having also represented the rolling elements and their contact with the raceways. The results obtained using the FEM have been correlated with the results of the new procedure.

Sign in / Sign up

Export Citation Format

Share Document