Effect of Hydrolysis on Mechanical Behavior of Bioabsorbable Composites

2014 ◽  
Vol 783-786 ◽  
pp. 1274-1279 ◽  
Author(s):  
Satoshi Kobayashi ◽  
Shusaku Yamaji
Keyword(s):  
Mechanical Behavior ◽  
Interfacial Strength ◽  
Nonlinear Behavior ◽  
Critical Energy ◽  
Stress Strain ◽  
Critical Energy Release Rate ◽  
Strain Behavior ◽  
Strain Relationship ◽  
Theoretical Results ◽  
Good Agreement

In this study, effect of hydrolysis in simulated body environment on mechanical behavior oftricalcium phosphate (TCP)/Poly(L-lactic acid) (PLLA) composites were analytically characterized.In order to predict stress-strain behavior after hydrolysis, damage micromechanical analysis proposedby the authors were utilized. In this model, nonlinear behavior in stress strain relationship weresimulated considering interfacial debonding between TCP particle and PLLA matrix. For the purposeof deciding the interfacial strength, such as critical energy release rate, curve fitting was conducted onthe result of the composites with 15wt% TCP content. Theoretical results on 5wt% and 10wt%composites using the interfacial strength obtained were in good agreement with experimental results.This result indicated that interfacial strength was independent from TCP fraction.

Mechanical Characterization of Assemblies Bonded With Pressure-Sensitive Adhesives (PSAs)

2015 ◽  
Author(s):  
Hao Huang ◽  
Abhijit Dasgupta ◽  
Ehsan Mirbagheri ◽  
Srini Boddapati
Keyword(s):  
Mechanical Behavior ◽  
Failure Modes ◽  
Mechanical Characterization ◽  
Bonding Temperature ◽  
Process Conditions ◽  
Second Phase ◽  
Loading Conditions ◽  
Stress Strain ◽  
Strain Behavior ◽  
Pressure Sensitive

The focus of this paper is on the stress-strain behavior and creep response of a pressure-sensitive adhesive (PSA) with and without carrier layers. This study consists of two phases. The first phase focuses on understanding of the effects of fabrication profiles, including bonding pressure, bonding temperature, bonding time, and aging time, on the PSA joint strength. This part of the study is used to identify an acceptable bonding and aging conditions for manufacturing a robust PSA bonded assembly. Specimens fabricated with this selected set of bonding process conditions are then used for mechanical characterization. The second phase focuses on the assembly’s mechanical behavior (stress-strain behavior and the creep curves) under different loading conditions, including loading stress, loading rate, and loading temperature. The mechanical behavior of PSA bonded assemblies is affected not only by the loading conditions, but also by the assembly architecture. The mechanical behaviors and failure modes of PSAs with and without carrier layers are compared. The reasons for these differences are also discussed.

A Method to Resolve the Properties of Individual Phases in Carbon-Black-Loaded Elastomer Blends

1991 ◽  
Vol 64 (2) ◽  
pp. 234-242
Author(s):  
R. F. Bauer ◽  
A. H. Crossland
Keyword(s):  
Carbon Black ◽  
Large Deformation ◽  
Polymer Phase ◽  
Stress Strain ◽  
Strain Behavior ◽  
Stress Behavior ◽  
Strain Relationship ◽  
Deformation Stress ◽  
The Individual ◽  
Vulcanization Process

Abstract Properties of the individual phases in a 70/30 carbon-black-loaded BR/NR blend could be successfully resolved using large deformation stress-strain modelling. Since the dispersed NR phase of the example had a lower modulus than the continuous BR phase, the interaction between the blend phases could be modelled by a simple parallel coupling arrangement. The stress behavior of each individual carbon-black-loaded polymer phase was then determined with respect to strain using a specially derived stress-strain relationship. The blend components also have to be characterized with respect to state-of-cure by empirically establishing how the parameters in the stress-strain relationship vary with respect to cure. The properties of the phases in the blend are then determined by finding the combination of component parameters which precisely reproduce the stress-strain behavior of the blend. In the demonstration example of this paper, there was evidence of a significant amount of curative migration between phases during the vulcanization process.

Effect of Characteristic Parameters of Exponential Cohesive Zone Model on Mode I Fracture of Laminated Composites

2012 ◽  
Vol 525-526 ◽  
pp. 409-412 ◽  
Author(s):  
Guo Wei Zhu ◽  
Yu Xi Jia ◽  
Peng Qu ◽  
Jia Qi Nie ◽  
Yun Li Guo
Keyword(s):  
Energy Release Rate ◽  
Energy Release ◽  
Release Rate ◽  
Laminated Composites ◽  
Peak Load ◽  
Interfacial Strength ◽  
Critical Energy ◽  
Mode I ◽  
Zone Model ◽  
Critical Energy Release Rate

Delamination is a particularly dangerous damage mode of high performance laminated composites. In order to describe the composites ductile cracking and its progressive evolution accurately, the adjusted exponential cohesive zone model (CZM) is adopted, which correlates the tensile traction with the corresponding interfacial separation along the fracturing interfacial zone. At first the adjusted exponential CZM is used to simulate the mode I delamination of the standard double cantilever beam (DCB). The simulated results are in good agreement with the corrected beam theory and the corresponding experimental results. Then in order to research how the interfacial properties influence the mode I fracture, the interfacial strength and the critical energy release rate are studied. The main results are obtained as follows. The interfacial strength plays a crucial role in the laminated composites delamination onset, and it affects the peak load significantly if there is not a pre-crack. Once the delamination propagation begins to occur in the laminated composites, the responses of the load-displacement plots are relatively insensitive to the interfacial strength, and only the critical energy release rate is of critical importance. Furthermore, the peak load increases with the increase of the critical energy release rate and interfacial strength.

scholarly journals Stress-Strain Behavior of Cementitious Materials with Different Sizes

2014 ◽  
Vol 2014 ◽  
pp. 1-11 ◽  
Author(s):  
Jikai Zhou ◽  
Pingping Qian ◽  
Xudong Chen
Keyword(s):  
Flexural Strength ◽  
Size Effect ◽  
Cement Mortar ◽  
Strain Curve ◽  
Cementitious Materials ◽  
Test Results ◽  
Stress Strain ◽  
Strain Behavior ◽  
Modified Equation ◽  
Good Agreement

The size dependence of flexural properties of cement mortar and concrete beams is investigated. Bazant’s size effect law and modified size effect law by Kim and Eo give a very good fit to the flexural strength of both cement mortar and concrete. As observed in the test results, a strong size effect in flexural strength is found in cement mortar than in concrete. A modification has been suggested to Li’s equation for describing the stress-strain curve of cement mortar and concrete by incorporating two different correction factors, the factors contained in the modified equation being established empirically as a function of specimen size. A comparison of the predictions of this equation with test data generated in this study shows good agreement.

A Cyclic Stress-Strain Constitutive Model for Polycrystalline Magnesium Alloy and its Application

2007 ◽  
Vol 546-549 ◽  
pp. 81-88
Author(s):  
Xiang Guo Zeng ◽  
Qing Yuan Wang ◽  
Jing Hong Fan ◽  
Zhan Hua Gao ◽  
Xiang He Peng
Keyword(s):  
Magnesium Alloy ◽  
Constitutive Model ◽  
Cyclic Stress ◽  
Stress And Strain ◽  
Slip Systems ◽  
Stress Strain ◽  
Strain Behavior ◽  
Cast Magnesium ◽  
Magnesium Alloy Am60 ◽  
Good Agreement

The stress-strain behavior of cast magnesium alloy (AM60) was investigated by strain-controlled cyclic testing carried out on MTS. In order to describe the cyclic stress and strain properties of AM60 by means of the energy storing characteristics of microstructure during irreversible deformation, a plastic constitutive model with no yielding surface was developed for single crystal by adopting a spring-dashpot mechanical system. Plastic dashpots reflecting the material transient response were introduced to describe the plasticity of slip systems. By utilizing the KBW self-consistent theory, a polycrystalline plastic constitutive model for Magnesium alloy was formed. The numerical analysis in the corresponding algorithm is greatly simplified as no process of searching for the activation of the slip systems and slip directions is required. The cyclic stress-strain behavior, based on this model, is discussed. The simulation results show good agreement with the experimental data for AM60.

Studies on the Stress-Strain Relationship Bovine Cortical Bone Based on Ramberg–Osgood Equation

2019 ◽  
Vol 141 (4) ◽  
Author(s):  
N. K. Sharma ◽  
M. D. Sarker ◽  
Saman Naghieh ◽  
Daniel X. B. Chen
Keyword(s):  
Cortical Bone ◽  
Linear Regression Analysis ◽  
Tensile Tests ◽  
Uniaxial Tensile ◽  
Loading Conditions ◽  
Stress Strain ◽  
Strain Behavior ◽  
Nonlinear Stress ◽  
Strain Relationship ◽  
Relationship Of

Bone is a complex material that exhibits an amount of plasticity before bone fracture takes place, where the nonlinear relationship between stress and strain is of importance to understand the mechanism behind the fracture. This brief presents our study on the examination of the stress–strain relationship of bovine femoral cortical bone and the relationship representation by employing the Ramberg–Osgood (R–O) equation. Samples were taken and prepared from different locations (upper, middle, and lower) of bone diaphysis and were then subjected to the uniaxial tensile tests under longitudinal and transverse loading conditions, respectively. The stress–strain curves obtained from tests were analyzed via linear regression analysis based on the R–O equation. Our results illustrated that the R–O equation is appropriate to describe the nonlinear stress–strain behavior of cortical bone, while the values of equation parameters vary with the sample locations (upper, middle, and lower) and loading conditions (longitudinal and transverse).

Analysis of the Mechanic Behavior and Rutting of Asphalt Concrete Using a Sand Model

1999 ◽  
Vol 15 (4) ◽  
pp. 177-184
Author(s):  
Ming-Lou Liu
Keyword(s):  
Asphalt Concrete ◽  
Stress Path ◽  
Plasticity Model ◽  
Test Results ◽  
Research Subjects ◽  
Stress Strain ◽  
Strain Behavior ◽  
Strain Relationship ◽  
Concrete Materials ◽  
Relationship Of

AbstractThe stress-strain relationship of the sand and asphalt concrete materials is one of the most important research subjects in the past, and many conctitutive laws for these materials have been proposed in the last two decades. In this study, the Vermeer plasticity model is modified and used to predict the behavior of the sand and asphalt concrete materials under different stress path conditions. The results show that the predictions and test results agree well under different stress path conditions. However, the orignal Vermeer model can not predict the stress-strain behavior of the asphalt concrete. Finally, the modified Vermeer plasticity model is incorporated with the pavement rutting model to predict the rut depth of pavement structure under traffic loadings.

The Maximum Stress in Optical Glass Fibers Under Two-Point Bending

2000 ◽  
Vol 123 (1) ◽  
pp. 70-73 ◽  
Author(s):  
Mikio Muraoka
Keyword(s):  
Axial Force ◽  
Maximum Stress ◽  
Optical Glass ◽  
Glass Fibers ◽  
Order Term ◽  
Nonlinear Behavior ◽  
Bending Stress ◽  
Stress Strain ◽  
Nonlinear Stress ◽  
Strain Relationship

The maximum stress in optical glass fibers subjected to two-point bending was evaluated by E. Suhir, “Effect of the Nonlinear Behavior of the Material on Two-Point Bending of Optical Glass Fibers,” ASME Journal of Electronic Packaging, Vol. 114, pp. 246–250, taking into account the shift in the neutral axis due to the nonlinear stress-strain relationship of the materials. However, the resulting distribution of bending stress on the fiber cross-section is not realistic because it produces a nonzero axial force. In the present study, we derive the correct formulas for evaluating the maximum stress under the valid condition that the bending stress does not contribute to the axial force. Moreover, we employ the nonlinear stress-strain relationship containing a third-order term of strain, which is more appropriate for the materials than that utilized by Suhir.

The Resolution of Elastomer Blend Properties by Stress-Strain Modelling. An Extension of the Model to Carbon-Black-Loaded Elastomers

1990 ◽  
Vol 63 (5) ◽  
pp. 779-791 ◽  
Author(s):  
R. F. Bauer ◽  
A. H. Crossland
Keyword(s):  
Carbon Black ◽  
Full Range ◽  
Filler Particle ◽  
Particle Surface ◽  
Practical Method ◽  
Particulate Phase ◽  
Stress Strain ◽  
Strain Behavior ◽  
Strain Relationship ◽  
Elastomer Blend

Abstract The unique stress-strain behavior of a carbon-black-loaded elastomer is due to the presence of a rigid, particulate phase, but also to the interaction of the elastomer chains with the filler. It is postulated that this interaction takes the form of adsorption on the filler-particle surface, which results in trapped entanglements. Upon deformation, the trapped chains are aligned parallel to the axis of stress. Thus, a practical stress-strain relationship could be developed which is capable to model the stress-strain behavior of compounds over the full range of extensions up to break. The analysis of a highly prestrained carbon-black-loaded NR compound in which the entanglement effect had been mechanically destroyed, demonstrated that the “sea-island” (SIP) coupling arrangement is most suitable for accounting for the interaction effect of the elastomer and carbon black. For moderately prestrained carbon-black-loaded NR and BR compounds a good fit of theory to experiment is obtained for a combination of the SIP coupling arrangement and the specially derived stress-strain relationship. Thus, a practical method is available for describing the deformation of carbon-black-loaded elastomers and for the modelling of carbon-black-loaded elastomer blends.

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