scholarly journals Biomechanical Behavior Characterization and Constitutive Models of Porcine Trabecular Tibiae

Biology ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 532
Author(s):  
Covadonga Quintana-Barcia ◽  
Cristina Rodríguez ◽  
Guillermo Álvarez ◽  
Antonio Maestro
Keyword(s):  
Trabecular Bone ◽  
Trauma Surgery ◽  
Constitutive Models ◽  
Longitudinal Direction ◽  
Experimental Results ◽  
Alternative Formulation ◽  
Plastic Behavior ◽  
Compression Tests ◽  
Confined Compression ◽  
Biomechanical Behavior

Customizing any trauma surgery requires prior planning by surgeons. Nowadays, the use of numerical tools is increasingly needed to facilitate this planning. The success of this analysis begins with the definition of all the mechanical constitutive models of the materials implied. Our target is the trabecular bone because almost all trauma surgeries are closely related to it. This work focuses on the experimental characterization of porcine trabecular tibiae and defining its best constitutive model. Therefore, different types of compression tests were performed with tibia samples. Once the potential constitutive models were defined, stress–strain state from numerical approaches were compared with the corresponding experimental results. Experimental results from uniaxial compression tests showed than trabecular bone exhibits clear anisotropy with more stiffness and strength when it is loaded in the tibia longitudinal direction. Results from confined compression tests confirmed that the plastic behavior of trabecular bone depends on the hydrostatic and deviatoric invariants, so an alternative formulation (crushable foam volumetric (CFV)) has been proposed to describe its behavior. A new method to obtain CFV characteristic parameters has been developed and validated. Predictions of the CFV model better describe trabecular bone mechanical behavior under confined conditions. In other cases, classical plasticity formulations work better.

scholarly journals A Study on the Application of Two Different Material Constitutive Models Used in the FE Simulation of the Cyclic Plastic Behavior of a Steel Beam-Column T-Stub Connection

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Wei Wang ◽  
Chenchen Zhang ◽  
Zeshen Li ◽  
Xuehong Gan
Keyword(s):  
Fe Simulation ◽  
Constitutive Models ◽  
Steel Structures ◽  
Experimental Results ◽  
Isotropic Hardening ◽  
Plastic Behavior ◽  
Q235 Steel ◽  
Cyclic Plastic ◽  
Cause Of Failure ◽  
Simulation Results

Seismic actions inevitably cause cyclic plastic deformations in steel frame connections, which is a common cause of failure in steel structures. Nonlinear finite element (FE) static analysis has been employed in the study of the cyclic plastic behavior of a T-stub connection based on the reported cyclic test on the corresponding extensively tested T-stub connection made of Q235 steel. In particular, the isotropic-hardening and Chaboche constitutive models were employed to predict both the stress distribution and plastic development on the T-stub and the hysteretic curves of the entire T-stub connection. The two constitutive models were calibrated by four material tests to describe the yield and hardening behaviors of the Q235 steel used to make this T-stub connection. The two sets of simulation results obtained from the simulations of the two FE models employed by the two different constitutive models were compared with each other and with the experimental results. The comparisons reveal that the simulation results are similar and in good agreement with the experimental results when the cumulative plastic deformation in the T-stub is small. However, the results of the FE analysis using the Chaboche model are in better agreement with the experimental results when the cumulative deformation in the T-sub is large. This study can provide a reference for FE simulation of the cyclic plastic behavior of steel connections, including the T-stub connection.

scholarly journals ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION NUMERIC AND EXPERIMENTAL ANALYSES: INFLUENCE OF TRABECULAR BONE CONSTITUTIVE MODEL

2021 ◽  
Vol 108 (Supplement_3) ◽  
Author(s):  
C Quintana Barcia ◽  
C Rodríguez González ◽  
C Betegón Biempica ◽  
G Álvarez Díaz ◽  
A Maestro
Keyword(s):  
Finite Element ◽  
Constitutive Model ◽  
Trabecular Bone ◽  
Acl Reconstruction ◽  
Cruciate Ligament ◽  
Computational Cost ◽  
Interference Screw ◽  
Compression Tests ◽  
Confined Compression ◽  
Von Mises

Abstract INTRODUCTION The number of variables that influence the success of an ACL reconstruction is such that, the use of numerical tools becomes increasingly necessary. In this work, a finite element model is developed to simulate the ACL reconstruction in its tibial insertion. MATERIAL AND METHODS Tibiae and ligaments porcine samples were used in this work. As the tibial fixation, an interference screw with a nominal diameter of 7mm and a length of 25mm is used. The plasty which replace the injured ligament was characterize using tensile tests. Uniaxial and confined compression tests, as well as indentation tests, were used for characterizing trabecular bone. Finite element methods were used for the implementation of the ACL reconstruction simulation, which studies the effect in the knee joint of all the elements involved (plasty, bone and interference screw). RESULTS None of the models available for the description of the trabecular bone behavior (von Mises, Hill and Crushable Foam), is capable of doing it in a completely proper manner. The use of one or the other constitutive model does not greatly influence the numerical simulation results. CONCLUSIONS As trabecular bone has a strongly anisotropic and non-symmetric mechanical behavior, none of the constitutive models available in the finite element code used is capable of fully describing it. Thus, the use of von Mises criterion is recommended, as it is the easiest to define and the one that requires the least numerical resources (lower computational cost).

Idealization through interactive modeling and experimental assessment of 3D-printed gyroid for trabecular bone scaffold

2021 ◽  
pp. 095441192110229
Author(s):  
Yogesh Tripathi ◽  
Mukul Shukla ◽  
Amba D. Bhatt
Keyword(s):  
Trabecular Bone ◽  
Fused Deposition Modeling ◽  
Poly Lactic Acid ◽  
Porous Scaffolds ◽  
Bone Scaffold ◽  
Compression Tests ◽  
Modeling Framework ◽  
Interactive Modeling ◽  
Native Bone ◽  
Fused Deposition

Porous scaffolds assisted bone tissue engineering is a viable alternative for reconstruction of large segmental bone defects caused by bone pathologies or trauma. In the current study, we intend to develop trabecular bone scaffolds using gyroid architecture. An interactive modeling framework is developed for the design of three-dimensional gyroid scaffolds using advanced generative tools including K3DSurf, MeshLab, and Netfabb. The suggested modeling approach resulted in uniform and interconnected pores. Subsequently, fused deposition modeling 3D-printing is employed to fabricate the scaffolds using poly lactic acid material. The pores interconnectivity, porosity, and surface finish of the fabricated scaffolds are characterized using micro-computer tomography and scanning electron microscopy. Additionally, to assess the performance of scaffolds as a bone substitute, compression, and in-vitro biocompatibility tests on sterilized scaffolds are conducted. Compression tests reveal mechanical strength in the range of native bone while human adipose-derived mesenchymal stem cells show high proliferation after 72 h of incubation. Based on these results, the fabricated gyroid scaffolds can be said to possess favorable properties for trabecular bone scaffold.

scholarly journals Analysis of the Influencing Factors of FDM-Supported Positions for the Compressive Strength of Printing Components

Materials ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 4008
Author(s):  
Zhengkai Feng ◽  
Heng Wang ◽  
Chuanjiang Wang ◽  
Xiujuan Sun ◽  
Shuai Zhang
Keyword(s):  
Compressive Strength ◽  
Stress Intensity ◽  
Influencing Factors ◽  
Fused Deposition Modeling ◽  
Experimental Results ◽  
Compression Tests ◽  
Suspended State ◽  
Fused Deposition ◽  
Deposition Modeling ◽  
Reference Experiment

Fused deposition modeling (FDM) has the advantage of being able to process complex workpieces with relatively simple operations. However, when processing complex components in a suspended state, it is necessary to add support parts to be processed and formed, which indicates an excessive dependence on support. The stress intensity of the supported positions of the printing components can be modified by changing the supporting model of the parts, their density, and their distance in relation to the Z direction in the FDM printing settings. The focus of the present work was to study the influences of these three modified factors on the stress intensity of the supporting position of the printing components. In this study, 99 sets of compression tests were carried out using a position of an FDM-supported part, and the experimental results were observed and analyzed with a 3D topographic imager. A reference experiment on the anti-pressure abilities of the printing components without support was also conducted. The experimental results clarify how the above factors can affect the anti-pressure abilities of the supporting positions of the printing components. According to the results, when the supporting density is 30% and the supporting distance in the Z direction is Z = 0.14, the compressive strength of the printing component is lowest. When the supporting density of the printing component is ≤30% and the supporting distance in the Z direction is Z ≥ 0.10, the compressive strength of printing without support is greater than that of the linear support model. Under the same conditions, the grid-support method offers the highest compressive strength.

Constitutive Modeling for Flow Stress Behavior of Nimonic 80A Superalloy During Hot Deformation Process

2016 ◽  
Vol 35 (3) ◽  
pp. 327-336 ◽  
Author(s):  
Sendong Gu ◽  
Liwen Zhang ◽  
Chi Zhang ◽  
Wenfei Shen
Keyword(s):  
Flow Stress ◽  
Constitutive Model ◽  
Hot Deformation ◽  
Critical Strain ◽  
Volume Fraction ◽  
Constitutive Models ◽  
Avrami Equation ◽  
Peak Strain ◽  
Compression Tests ◽  
Nimonic 80A

AbstractThe hot deformation characteristics of nickel-based alloy Nimonic 80A were investigated by isothermal compression tests conducted in the temperature range of 1,000–1,200°C and the strain rate range of 0.01—5 s–1on a Gleeble-1500 thermomechanical simulator. In order to establish the constitutive models for dynamic recrystallization (DRX) behavior and flow stress of Nimonic 80A, the material constantsα,nand DRX activation energyQin the constitutive models were calculated by the regression analysis of the experimental data. The dependences of initial stress, saturation stress, steady-state stress, dynamic recovery (DRV) parameter, peak strain, critical strain and DRX grain size on deformation parameters were obtained. Then, the Avrami equation including the critical strain for DRX and the peak strain as a function of strain was established to describe the DRX volume fraction. Finally, the constitutive model for flow stress of Nimonic 80A was developed in DRV region and DRX region, respectively. The flow stress values predicted by the constitutive model are in good agreement with the experimental ones, which indicates that the constitutive model can give an accurate estimate for the flow stress of Nimonic 80A under the deformation conditions.

Characterization of Flow Stress for Commercially Pure Titanium Subjected to Electrically-Assisted Deformation

2013 ◽  
Author(s):  
James Magargee ◽  
Fabrice Morestin ◽  
Jian Cao
Keyword(s):  
Flow Stress ◽  
Heating Temperature ◽  
Pure Titanium ◽  
Constitutive Models ◽  
Plastic Behavior ◽  
Commercially Pure Titanium ◽  
Coupled Models ◽  
Commercially Pure ◽  
Electrically Assisted ◽  
Tension And Compression

Uniaxial tension tests were conducted on thin commercially pure titanium sheets subjected to electrically-assisted deformation using a new experimental setup to decouple thermal-mechanical and possible electroplastic behavior. The observed absence of stress reductions for specimens air-cooled to near room temperature motivated the need to reevaluate the role of temperature on modeling the plastic behavior of metals subjected to electrically-assisted deformation, an item that is often overlooked when invoking electroplasticity theory. As a result, two empirical constitutive models, a modified-Hollomon and the Johnson-Cook models of plastic flow stress, were used to predict the magnitude of stress reductions caused by the application of constant DC current and the associated Joule heating temperature increase during electrically-assisted tension experiments. Results show that the thermal-mechanical coupled models can effectively predict the mechanical behavior of commercially pure titanium in electrically-assisted tension and compression experiments.

Effect of Defect on Elastic/Plastic and Creep Behavior of Bone: A Finite Element Study

2007 ◽  
Author(s):  
A. Ajdari ◽  
P. K. Canavan ◽  
H. Nayeb-Hashemi ◽  
G. Warner
Keyword(s):  
Mechanical Properties ◽  
Finite Element ◽  
Trabecular Bone ◽  
Fatigue Loading ◽  
Dimensional Structure ◽  
Plastic Behavior ◽  
Element Analysis ◽  
Elastic Plastic ◽  
Local Bone ◽  
Osteoporotic Vertebral Fractures

Three-dimensional structure of trabecular bone can be modeled by 2D or 3D Voronoi structure. The effect of missing cell walls on the mechanical properties of 2D honeycombs is a first step towards understanding the effect of local bone resorption due to osteoporosis. In patients with osteoporosis, bone mass is lost first by thinning and then by resorption of the trabeculae [1]. Furthermore, creep response is important to analyze in cellular solids when the temperature is high relative to the melting temperature. For trabecular bone, as body temperature (38 °C) is close to the denaturation temperature of collagen (52 °C), trabecular bone creeps [1]. Over the half of the osteoporotic vertebral fractures that occur in the elderly, are the result of the creep and fatigue loading associated with the activities of daily living [2]. The objective of this work is to understand the effect of missing walls and filled cells on elastic-plastic behavior of both regular hexagonal and non-periodic Voronoi structures using finite element analysis. The results show that the missing walls have a significant effect on overall elastic properties of the cellular structure. For both regular hexagonal and Voronoi materials, the yield strength of the structure decreased by more than 60% by introducing 10% missing walls. In contrast, the results indicate that filled cells have much less effect on the mechanical properties of both regular hexagonal and Voronoi materials.

scholarly journals In-plane Shear Strengthening of Unreinforced Masonry Walls Using GFRP Jacketing

2017 ◽  
Author(s):  
Enea Mustafaraj ◽  
Yavuz Yardim
Keyword(s):  
Experimental Results ◽  
Test Results ◽  
Compression Tests ◽  
Shear Strengthening ◽  
Plane Shear ◽  
Standard Size ◽  
Reinforced Polymer ◽  
Glass Fiber Reinforced ◽  
Diagonal Compression ◽  
Before And After

In this paper, it is presented the experimental results of a campaign on diagonal compression tests, as of ASTM E519-02, to assess and compare the in-plane behavior of standard size of 1200 × 1200 × 250 mm, for three unreinforced and three reinforced wall panels by glass fiber reinforced polymer (GFRP) embedded in an inorganic matrix.From the diagonal compression test results, were determined some of the main mechanical parameters such as: shear strength, modulus of rigidity and ductility, before and after application of the reinforcement.The experimental results showed that the GFRP reinforced panels exhibited a significant increase of 127% in shear resistance, 1100% in ductility and 650% in modulus of rigidity when compared to unreinforced panels.It was concluded that this technique provided satisfactory results and can be considered a suitable method for repair of masonry structures.

Characterization of the Effect of Corrugation Angles on Hydrodynamic and Heat Transfer Performance of Four-Start Spiral Tubes

2001 ◽  
Vol 123 (6) ◽  
pp. 1149-1158 ◽  
Author(s):  
X. D. Chen ◽  
X. Y. Xu ◽  
S. K. Nguang ◽  
Arthur E. Bergles
Keyword(s):  
Heat Transfer ◽  
Evaluation Criteria ◽  
Geometry Optimization ◽  
Longitudinal Direction ◽  
Experimental Results ◽  
Neural Network Modeling ◽  
Transfer Coefficients ◽  
Correlation Models ◽  
Friction Factors ◽  
Double Pipe

A series of four-start spirally corrugated tubes has been subjected to heat transfer and hydrodynamic testing in a double-pipe heat exchanger. The study has been focused on the non-symmetric nature of the corrugation angles along the longitudinal direction. Both friction factors and heat transfer coefficients inside the tubes have been correlated against various process parameters. It can be shown that by altering the internal non-symmetric wavy shapes of the tubes, one is able to manipulate heat transfer and friction characteristics. The experimental results have been compared with some popular correlation models developed previously for both friction and heat transfer for corrugated tubes. Considerable differences between the experimental results and the predictions made using the existing correlations have been found and the probable causes have been discussed. Performance evaluation criteria are presented using the standard constant power criterion. A neural network modeling approach has been taken so that, based on the limited data, one can generate the contour showing the effect of corrugation angle on heat transfer coefficient for geometry optimization purposes.

The Physical and Computer Modeling of Plastic Deformation of Low Carbon Steel in Semisolid State

2009 ◽  
Vol 131 (4) ◽  
Author(s):  
Marcin Hojny ◽  
Miroslaw Glowacki
Keyword(s):  
Computer Simulation ◽  
Low Carbon Steel ◽  
Mass Conservation ◽  
Analytical Form ◽  
Plastic Behavior ◽  
Volume Loss ◽  
Low Carbon ◽  
Compression Tests ◽  
Thermomechanical Model ◽  
Numerical Errors

This paper reports the results of theoretical and experimental work leading to the construction of a dedicated finite element method (FEM) system allowing the computer simulation of physical phenomena accompanying the steel sample testing at temperatures that are characteristic for integrated casting and rolling of steel processes, which was equipped with graphical, database oriented pre- and postprocessing. The kernel of the system is a numerical FEM solver based on a coupled thermomechanical model with changing density and mass conservation condition given in analytical form. The system was also equipped with an inverse analysis module having crucial significance for interpretation of results of compression tests at temperatures close to the solidus level. One of the advantages of the solution is the negligible volume loss of the deformation zone due to the analytical form of mass conservation conditions. This prevents FEM variational solution from unintentional specimen volume loss caused by numerical errors, which is inevitable in cases where the condition is written in its numerical form. It is very important for the computer simulation of deformation processes to be running at temperatures characteristic of the last stage of solidification. The still existing density change in mushy steel causes volume changes comparable to those caused by numerical errors. This paper reports work concerning the adaptation of the model to simulation of plastic behavior of axial-symmetrical steel samples subjected to compression at temperature levels higher than 1400°C. The emphasis is placed on the computer aided testing procedure leading to the determination of mechanical properties of steels at temperatures that are very close to the solidus line. Example results of computer simulation using the developed system are presented as well.

Sign in / Sign up

Export Citation Format

Share Document