Linear and Nonlinear Approach of Hydro-Pneumatic Tensioner Modeling for Spar Global Performance

2007 ◽  
Author(s):  
Chan K. Yang ◽  
Arcandra Tahar ◽  
M. H. Kim
Keyword(s):  
Coupling Effect ◽  
Time Domain Analysis ◽  
Ideal Gas ◽  
Fe Model ◽  
Floating Bodies ◽  
Fe Method ◽  
Stick Slip ◽  
Nonlinear Approach ◽  
The Relationship ◽  
Fully Coupled

This paper presents a numerical model of top tension risers (TTRs) with hydro-pneumatic tensioner for Spar application in the Gulf of Mexico environment. Nonlinearity of the stiffness and friction characteristics of the tensioner combined with stick-slip behavior of riser keel joint is investigated. The relationship between tensions and strokes for hydro-pneumatic tensioner is based on the ideal gas equation where the isotropic gas constant can be varied to achieve an optimum stroke design based on tensioner stiffness. Challenges of modeling the coupling effects in the finite element (FE) method between the tensioner and hull motion are also presented. This new FE model is implemented into CHARM3D, a fully coupled time domain analysis program of floating bodies. The effect of nonlinearity of tensioner curve, tensioner friction and riser keel friction is intensively investigated. The resultant global motion, TTR stroke and tensions are systematically compared with those of a simple engineering approach in which the nonlinear coupling effect is captured by linearization.

Linear and Nonlinear Approach of Hydropneumatic Tensioner Modeling for Spar Global Performance

2009 ◽  
Vol 132 (1) ◽  
Author(s):  
Chan K. Yang ◽  
M. H. Kim
Keyword(s):  
Coupling Effect ◽  
Ideal Gas ◽  
Fe Model ◽  
Floating Bodies ◽  
Fe Method ◽  
Stick Slip ◽  
Nonlinear Approach ◽  
The Relationship ◽  
Fully Coupled ◽  
The Ideal

This paper deals with a numerical model of top tension risers with hydropneumatic tensioner for Spar application in the Gulf of Mexico environment. The nonlinearity of the stiffness and the friction characteristics of the tensioner combined with stick-slip behavior of the riser keel joint are investigated. The relationship between tensions and strokes for the hydropneumatic tensioner is based on the ideal gas equation where the isotropic gas constant can be varied to achieve an optimum stroke design based on the tensioner stiffness. Challenges of modeling the coupling effects in the finite element (FE) method between the tensioner and hull motion are also presented. This new FE model is implemented into a fully-coupled time-domain coupled-dynamics-analysis program for floating bodies. The effect of nonlinearity of tensioner curve, tensioner friction, and riser keel friction is intensively investigated. The resultant global motion, TTR stroke, and tensions are systematically compared with those of a simple engineering approach, in which the nonlinear coupling effect is captured by linearization.

scholarly journals Artificial Finger Skin having Ridges and Distributed Tactile Sensors used for Grasp Force Control

2002 ◽  
Vol 14 (2) ◽  
pp. 140-146 ◽  
Author(s):  
Daisuke Yamada ◽  
◽  
Takashi Maeno ◽  
Yoji Yamada ◽  
Keyword(s):  
Reaction Force ◽  
Frictional Coefficient ◽  
Dynamic Contact ◽  
Fe Model ◽  
Tactile Sensors ◽  
Fe Method ◽  
Stick Slip ◽  
Grasping Force ◽  
Grasp Force ◽  
Finger Skin

An artificial elastic finger skin for robot fingers has been developed for controlling grasp force when weight and frictional coefficient of the grasped object are unknown. The elastic finger skin has ridges at the surface to divide the stick/slip area. It also has a pair of tactile sensors embedded per ridge similar to human fingertips. The surface of the whole finger is curved so that reaction force distributes. A Finite Element (FE) model of the elastic finger skin was made to conduct dynamic contact analysis using a FE method to design the elastic finger skin in detail. Then the elastic finger skin was made. We confirmed by calculation and experiment that incipient slippage of the ridge occurring near the edge of contact is detected. Then, grasp was controlled using the finger. Arbitrary objects were lifted by incipient slippage near the edge of contact. We found that artificial finger skin is useful for controlling grasping force when the weight and friction coefficient between the elastic finger skin and grasping object are unknown.

A novel model of Z-pin insertion in prepreg based on fracture mechanics

2021 ◽  
pp. 095440542110144
Author(s):  
Guobiao Ji ◽  
Liang Cheng ◽  
Shaohua Fei ◽  
Jiangxiong Li ◽  
Yinglin Ke
Keyword(s):  
Fracture Toughness ◽  
Fracture Mechanics ◽  
Analytical Model ◽  
Model Parameters ◽  
Force Model ◽  
Fe Model ◽  
Cohesive Elements ◽  
Fe Method ◽  
Insertion Force ◽  
Mechanics Model

Through-thickness reinforcement is a promising solution to the problem of delamination susceptibility in laminated composites. Modeling Z-pin–prepreg interaction is essential for accurate robotics-assisted Z-pin insertion. In this paper, a novel Z-pin insertion force model combining the classical cohesive finite element (FE) method with a dynamic analytical fracture mechanics model is proposed. The velocity-dependent cohesive elements, in which the fracture toughness is provided by the analytical model, are implemented in Z-pin insertion FE model to predict the crack initiation and propagation. Then Z-pin insertion experiments are performed on prepreg sample with metallic Z-pins at different velocities to identify the analytical model parameters and validate the simulation predictions offered by the model. Dynamics of Z-pin interaction with inhomogeneous prepreg is described and the effects of insertion velocity on prepreg contact force are studied. Results show that the force model agrees well with experiments and the fracture toughness rises with the increasing Z-pin insertion velocity.

Development and analysis of composite overwrapped pressure vessels for hydrogen storage

2021 ◽  
pp. 002199832110335
Author(s):  
Osman Kartav ◽  
Serkan Kangal ◽  
Kutay Yücetürk ◽  
Metin Tanoğlu ◽  
Engin Aktaş ◽  
...  
Keyword(s):  
Hydrogen Storage ◽  
Damage Model ◽  
Pressure Vessels ◽  
Filament Winding ◽  
Burst Pressure ◽  
Fe Model ◽  
Fe Method ◽  
Liner Material ◽  
Mechanical Performances ◽  
Metallic Liner

In this study, composite overwrapped pressure vessels (COPVs) for high-pressure hydrogen storage were designed, modeled by finite element (FE) method, manufactured by filament winding technique and tested for burst pressure. Aluminum 6061-T6 was selected as a metallic liner material. Epoxy impregnated carbon filaments were overwrapped over the liner with a winding angle of ±14° to obtain fully overwrapped composite reinforced vessels with non-identical front and back dome layers. The COPVs were loaded with increasing internal pressure up to the burst pressure level. During loading, deformation of the vessels was measured locally with strain gauges. The mechanical performances of COPVs designed with various number of helical, hoop and doily layers were investigated by both experimental and numerical methods. In numerical method, FE analysis containing a simple progressive damage model available in ANSYS software package for the composite section was performed. The results revealed that the FE model provides a good correlation as compared to experimental strain results for the developed COPVs. The burst pressure test results showed that integration of doily layers to the filament winding process resulted with an improvement of the COPVs performance.

scholarly journals CAD-Based 3D-FE Modelling of AISI-D3 Turning with Ceramic Tooling

Machines ◽  
2021 ◽  
Vol 9 (1) ◽  
pp. 4
Author(s):  
Panagiotis Kyratsis ◽  
Anastasios Tzotzis ◽  
Angelos Markopoulos ◽  
Nikolaos Tapoglou
Keyword(s):  
Statistical Model ◽  
Cutting Speed ◽  
Depth Of Cut ◽  
Fe Model ◽  
Fe Modelling ◽  
3D Finite Element ◽  
Force Components ◽  
Four Levels ◽  
The Relationship ◽  
Strong Agreement

In this study, the development of a 3D Finite Element (FE) model for the turning of AISI-D3 with ceramic tooling is presented, with respect to four levels of cutting speed, feed, and depth of cut. The Taguchi method was employed in order to create the orthogonal array according to the variables involved in the study, reducing this way the number of the required simulation runs. Moreover, the possibility of developing a prediction model based on well-established statistical tools such as the Response Surface Methodology (RSM) and the Analysis of Variance (ANOVA) was examined, in order to further investigate the relationship between the cutting speed, feed, and depth of cut, as well as their influence on the produced force components. The findings of this study point out an increased correlation between the experimental results and the simulated ones, with a relative error below 10% for most tests. Similarly, the values derived from the developed statistical model indicate a strong agreement with the equivalent numerical values due to the verified adequacy of the statistical model.

scholarly journals Modelling human skull growth: a validated computational model

2017 ◽  
Vol 14 (130) ◽  
pp. 20170202 ◽  
Author(s):  
Joseph Libby ◽  
Arsalan Marghoub ◽  
David Johnson ◽  
Roman H. Khonsari ◽  
Michael J. Fagan ◽  
...  
Keyword(s):  
Computational Model ◽  
Three Dimensional ◽  
Basic Knowledge ◽  
Fe Model ◽  
Adult Size ◽  
Fe Method ◽  
Percentage Difference ◽  
Skull Growth

During the first year of life, the brain grows rapidly and the neurocranium increases to about 65% of its adult size. Our understanding of the relationship between the biomechanical forces, especially from the growing brain, the craniofacial soft tissue structures and the individual bone plates of the skull vault is still limited. This basic knowledge could help in the future planning of craniofacial surgical operations. The aim of this study was to develop a validated computational model of skull growth, based on the finite-element (FE) method, to help understand the biomechanics of skull growth. To do this, a two-step validation study was carried out. First, an in vitro physical three-dimensional printed model and an in silico FE model were created from the same micro-CT scan of an infant skull and loaded with forces from the growing brain from zero to two months of age. The results from the in vitro model validated the FE model before it was further developed to expand from 0 to 12 months of age. This second FE model was compared directly with in vivo clinical CT scans of infants without craniofacial conditions ( n = 56). The various models were compared in terms of predicted skull width, length and circumference, while the overall shape was quantified using three-dimensional distance plots. Statistical analysis yielded no significant differences between the male skull models. All size measurements from the FE model versus the in vitro physical model were within 5%, with one exception showing a 7.6% difference. The FE model and in vivo data also correlated well, with the largest percentage difference in size being 8.3%. Overall, the FE model results matched well with both the in vitro and in vivo data. With further development and model refinement, this modelling method could be used to assist in preoperative planning of craniofacial surgery procedures and could help to reduce reoperation rates.

Effects of countersunk hole geometry errors on the fatigue performance of CFRP bolted joints

2021 ◽  
pp. 095440542110285
Author(s):  
Xuda Qin ◽  
Xingfeng Cao ◽  
Hao Li ◽  
Meng Zhou ◽  
Ende Ge ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Bolted Joints ◽  
Fatigue Performance ◽  
Machining Process ◽  
Fe Model ◽  
Hole Making ◽  
Hole Geometry ◽  
Geometry Error ◽  
The Relationship ◽  
Hole Machining

Due to good aerodynamic performance and reliability, countersunk bolt joint is one of the most commonly used connection methods for carbon fiber reinforced polymer (CFRP) components in the aircraft. However, the countersunk hole machining process is inevitably accompanied by geometric errors, which will directly affect the mechanical properties of the joint structure. This paper presents a numerical and experimental investigation on the effect of countersunk hole geometry errors on the fatigue performance of CFRP bolted joints. FE model of CFRP countersunk bolted joints with designed geometry errors are established, and the rationality of the FE analysis was verified by fatigue life and failure forms. The CFRP bolted structure failure mechanism under fatigue load and influence of hole-making geometry error (including countersunk fillets radius, countersunk depth, and countersunk angle) on the fatigue life are investigated. Based on the relationship between fatigue life and the geometry error, the corresponding tolerances for CFRP bolt joint countersunk hole are determined as well. The research results can provide a reference for establishing reasonable geometric accuracy requirements for CFRP joint hole machining.

Failure behavior analysis of steel strip–reinforced flexible pipe under combined tension and internal pressure

2018 ◽  
Vol 33 (6) ◽  
pp. 727-753
Author(s):  
Wei Chen ◽  
Haichao Xiong ◽  
Yong Bai
Keyword(s):  
Internal Pressure ◽  
Numerical Study ◽  
Steel Strip ◽  
Sensitivity Study ◽  
Failure Behavior ◽  
Load Path ◽  
Flexible Pipe ◽  
Fe Method ◽  
Axial Extension ◽  
The Relationship

The mechanical behaviors of steel strip–reinforced flexible pipe (steel strip PSP) under combined axial extension → internal pressure ( T→ P) load path were investigated. Typical failure characteristics of pipe samples under pure internal pressure and T→ P load path were identified in the full-scale experiments. A theoretical model for pipe under tension load was proposed to capture the relationship between axial extension of the pipe body and stress state of the steel strip. Numerical study based on finite element (FE) method was conducted to simulate the experiment process, and good agreement between FE data and experiment results were observed. Sensitivity study was conducted to study the effect of some key parameters on the pipe antiburst capacities in T→P load path; the effect of preloaded internal pressure on the pipe tensile capacity in P→T load path was also studied. Useful conclusions were drawn for the design and application of the steel strip PSP.

scholarly journals 3D Finite Element Model Simulating the Behaviour of Filling Soils Used to Set Up a New Placement Method for Separate Sewer Systems

2019 ◽  
Vol 8 (3) ◽  
pp. 87-98
Author(s):  
Alaa Abbas ◽  
Felicite Ruddock ◽  
Rafid Alkhaddar ◽  
Glynn Rothwell ◽  
Iacopo Carnacina ◽  
...  
Keyword(s):  
Finite Element ◽  
Soil Properties ◽  
Model Simulation ◽  
New Method ◽  
Traffic Load ◽  
Scale Model ◽  
Fe Model ◽  
Fe Method ◽  
Buried Pipes ◽  
The Impact

The use of a finite element (FE) method and selection of the appropriate model to simulate soil elastoplastic behaviour has confirmed the importance and sensitivity of the soil properties on the accuracy when compared with experimental data. The properties of the filling soil play a significant role in determining levels of deformation and displacement of both the soil and subterranean structures when using the FE model simulation. This paper investigates the impact of the traffic load on the filling soil deformation when using the traditional method, one pipe in a trench, and a new method, two pipes in a single trench one over the other, for setting up a separate sewer system. The interaction between the buried pipes and the filling soils has been simulated using an elastoplastic FE model. A modified Drucker–Prager cap constitutive model was used to simulate the stress-strain behaviours of the soil. A series of laboratory tests were conducted to identify the elastoplastic properties of the composite soil used to bury the pipes. The FE models were calibrated using a physical lab model for testing the buried pipes under applied load. This allows the FE model to be confidently upgraded to a full-scale model. The pipe-soil interactions were found to be significantly influenced by the soil properties, the method of placing the pipes in the trench and the diameters of the buried pipes. The deformation of the surface soil was decreased by approximately 10% when using the new method of setting up the separate sewer.

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