scholarly journals Modeling of a non-local stimulus for bone remodeling process under cyclic load: Application to a dental implant using a bioresorbable porous material

2016 ◽  
Vol 22 (9) ◽  
pp. 1790-1805 ◽  
Author(s):  
Ivan Giorgio ◽  
Ugo Andreaus ◽  
Daria Scerrato ◽  
Piero Braidotti
Keyword(s):  
Dental Implant ◽  
Strain Energy ◽  
Cyclic Load ◽  
External Action ◽  
Mechanical Stimulus ◽  
Point Of View ◽  
Material Behavior ◽  
Local Stimulus ◽  
Non Local ◽  
Load Variable

In this paper, a numerical method based on finite elements is used to study the phenomena of resorption and growth of bone tissue and resorption of the biomaterial in the neighborhood of a dental implant fixture of the type IntraMobil Zylinder. The mechanical stimulus that drives these processes is a linear combination of strain energy and viscous dissipation. To simulate the implant, an axisymmetric model has been used from the point of view of the geometry; the material behavior is described in the poro-visco-elastic frame. The external action is represented by a load variable with sinusoidal law characterized by different frequencies. Investigated aspects are the influence of the load frequency and of the lazy zone on the remodeling process.

scholarly journals Modeling and theoretical description of magnetic hybrid materials—bridging from meso- to macro-scales

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Andreas M. Menzel ◽  
Hartmut Löwen
Keyword(s):  
Colloidal Particles ◽  
Colloidal Particle ◽  
Theoretical Description ◽  
Point Of View ◽  
Material Behavior ◽  
Theoretical Point ◽  
Mechanical Stiffness ◽  
Theoretical Approaches ◽  
Theoretical Predictions ◽  
Particle Level

Abstract Magnetic gels and elastomers consist of magnetic or magnetizable colloidal particles embedded in an elastic polymeric matrix. Outstanding properties of these materials comprise reversible changes in their mechanical stiffness or magnetostrictive distortions under the influence of external magnetic fields. To understand such types of overall material behavior from a theoretical point of view, it is essential to characterize the substances starting from the discrete colloidal particle level. It turns out that the macroscopic material response depends sensitively on the mesoscopic particle arrangement. We have utilized and developed several theoretical approaches to this end, allowing us both to reproduce experimental observations and to make theoretical predictions. Our hope is that both these paths help to further stimulate the interest in these fascinating materials.

scholarly journals Contact interactions in complex fibrous metamaterials

2021 ◽  
Author(s):  
Mario Spagnuolo ◽  
Antonio M. Cazzani
Keyword(s):  
Strain Energy ◽  
Point Of View ◽  
The Other ◽  
Contact Interactions ◽  
Coupling Term ◽  
Dissipation Potential ◽  
Parallel Fibers ◽  
Mathematical Point

AbstractIn this work, an extension of the strain energy for fibrous metamaterials composed of two families of parallel fibers lying on parallel planes and joined by connective elements is proposed. The suggested extension concerns the possibility that the constituent fibers come into contact and eventually scroll one with respect to the other with consequent dissipation due to friction. The fibers interact with each other in at least three different ways: indirectly, through microstructural connections that could allow a relative sliding between the two families of fibers; directly, as the fibers of a family can touch each other and can scroll introducing dissipation. From a mathematical point of view, these effects are modeled first by introducing two placement fields for the two fiber families and adding a coupling term to the strain energy and secondly by adding two other terms that take into account the interdistance between the parallel fibers and the Rayleigh dissipation potential (to account for friction).

Improving the Long-Term Performance of Elastomeric Seals by Material Behavior Design

2009 ◽  
Vol 131 (4) ◽  
Author(s):  
Ryan B. Sefkow ◽  
Nicholas J. Maciejewski ◽  
Barney E. Klamecki
Keyword(s):  
Energy Density ◽  
Contact Pressure ◽  
Strain Energy ◽  
Applied Pressure ◽  
Material Behavior ◽  
Time Dependent ◽  
Ring Section ◽  
Stiff Material ◽  
Elastomeric Seals

Previously it was shown that including smaller inset regions of less stiff material in the larger O-ring section at locations of high stress results in lower strain energy density in the section. This lower energy content is expected to lead to improved long-term seal performance due to less permanent material deformation and so less loss of seal-housing contact pressure. The shape of the inset region, the time-dependent change in material properties, and hence change in seal behavior over time in use were not considered. In this research experimental and numerical simulation studies were conducted to characterize the time-dependent performance of O-ring section designs with small inset regions of different mechanical behaviors than the larger surrounding section. Seal performance in terms of the rate of loss of contact pressure of modified designs and a baseline elastic, one-material design was calculated in finite element models using experimentally measured time-dependent material behavior. The elastic strain energy fields in O-ring sections were calculated under applied pressure and applied displacement loadings. The highest stress, strain, and strain energy regions in O-rings are near seal-gland surface contacts with significantly lower stress in regions of applied pressure. If the size of the modified region of the seal is comparable to the size of the highest energy density region, the shape of the inset is not a major factor in determining overall seal section behavior. The rate of loss of seal-housing contact pressure over time was less for the modified design O-ring sections compared with the baseline seal design. The time-dependent performance of elastomeric seals can be improved by designing seals based on variation of mechanical behavior of the seal over the seal section. Improvement in retention of sealing contact pressure is expected for seal designs with less stiff material in regions of high strain energy density.

Observation of Fatigue Damage to Gear Tooth Using Image Processing

2007 ◽  
Author(s):  
Tomoya Masuyama ◽  
Takuya Ikeda ◽  
Satoshi Yoshiizumi ◽  
Katsumi Inoue
Keyword(s):  
Image Processing ◽  
Acoustic Emission ◽  
Strain Distribution ◽  
Cyclic Load ◽  
Early Stage ◽  
Gear Tooth ◽  
Digital Camera ◽  
Correlation Method ◽  
Point Of View ◽  
Strain Diagram

The detection of damage in early stage of fatigue is important for a reliable evaluation of gear life and strength. From this point of view, the variation of strain distribution in a tooth due to cyclic load contains useful information because the fatigue crack will initiate as a result of the accumulation of plastic strain. Meanwhile, digital image equipments are widely used in our life and the performance is in progress. We took digital pictures of cyclic loaded tooth by the digital camera and compared with the picture of no load to find displacement. The strain distribution of tooth is calculated by the correlation method using those pictures. The initiation of a micro crack is observed by the method. It is also confirmed by the detection of acoustic emission wave with higher energy. The variation of stress-strain diagram in fatigue process is presented, and this illustrates the increase of strain in the final stage of fatigue.

Influence of Alloy Behavior on Multiaxial Fatigue Lifing Criteria for Turbine Disk Bores

2014 ◽  
Author(s):  
D. J. Greving ◽  
P. T. Kantzos ◽  
M. N. Menon
Keyword(s):  
Low Cycle Fatigue ◽  
Turbine Disk ◽  
Multiaxial Fatigue ◽  
Point Of View ◽  
Material Behavior ◽  
Tensile Yield Strength ◽  
Failure Initiation ◽  
Disk Alloy ◽  
Significant Difference ◽  
Nickel Base

In a previous paper, a criterion for multiaxial lifing of turbine disk bores made from a nickel base super alloy, DP-718, was substantiated using results from spin pit testing of mini disks. In this paper, another turbine and compressor disk alloy, Alloy 10, exhibiting a different material behavior than DP-718 is examined from multiaxial point of view. This new alloy manufactured by powder metallurgy processing, has a coarser grain size, lower tensile yield strength, contains a much finer distribution of brittle carbides in its microstructure and shows a significant difference in failure initiation behavior under low cycle fatigue when compared to DP-718. Under the multiaxiality conditions experienced by disk bores, Alloy-10 lives seem to correlate well using an effective stress based criterion, whereas DP-718 was found to follow principal stress based criterion. Interesting differences between DP-718 and Alloy-10 in alloy and fractographic behavior under uniaxial and multiaxial conditions are discussed.

Material Characterization for Sheet-Bulk Metal Forming

2012 ◽  
Vol 504-506 ◽  
pp. 1029-1034 ◽  
Author(s):  
Bernd Arno Behrens ◽  
Kathrin Voges-Schwieger ◽  
Anas Bouguecha ◽  
Jens Mielke ◽  
Milan Vucetic
Keyword(s):  
Metal Forming ◽  
Material Characterization ◽  
Cyclic Load ◽  
Material Behavior ◽  
Forming Force ◽  
Forming Process ◽  
Bulk Metal ◽  
Bulk Metal Forming ◽  
Metal Forming Process

Sheet-bulk metal forming is a novel manufacturing technology, which unites the advantages and design solutions of sheet metal and bulk metal forming. To challenge the high forming force the process is superimposed with an oscillation in the main flow of the process. The paper focuses on the characterization of the material behavior under cyclic load and the effects for the sheet bulk metal forming process.

An Expression of Strain Energy with Couple Stresses

1984 ◽  
Vol 8 (2) ◽  
pp. 63-69
Author(s):  
S.K. Lakhanpal
Keyword(s):  
Material Properties ◽  
Strain Energy ◽  
Load Transfer ◽  
Modern Technology ◽  
Material Behavior ◽  
Couple Stresses ◽  
Energy Expression

Modern Technology has required a continuous search for better materials. Hence, the desire among engineers to study the material properties rigorously. Throughout the literature, the concept of load transfer is based on linear stresses. However, the material behavior is better defined when load transfer is considered to be by couple stresses, in addition to linear stresses. The strain energy expression is an important tool for the study of the material. With this in mind, an expression with couple stresses included is developed.

A Modified Gradient Plasticity Theory for Micro-Bending and Micro-Torsion Size Effects

2004 ◽  
Author(s):  
George Z. Voyiadjis ◽  
Rashid K. Abu Al-Rub
Keyword(s):  
Size Effects ◽  
Scale Parameter ◽  
Plasticity Theory ◽  
Material Behavior ◽  
Length Scale Parameter ◽  
Length Scale ◽  
Gradient Plasticity ◽  
Non Local ◽  
Material Length Scale ◽  
Material Length

The definition and magnitude of the intrinsic length scale are keys to the development of the theory of plasticity that incorporates size effects. Gradient plasticity theory with a material length scale parameter is successfully in capturing the size dependence of material behavior at the micron scale. However, a fixed value of the material length-scale is not always realistic and that different problems could require different values. Moreover, a linear coupling between the local and non-local terms in the gradient plasticity theory is not always realistic and that different problems could require different couplings. A generalized gradient plasticity model with a non-fixed length scale parameter is proposed. This model assesses the sensitivity of predictions in the way in which the local and non-local parts are coupled. The proposed model gives good predictions of the size effect in micro-bending tests of thin films and micro-torsion tests of thin wires.

Finite Element Based Automated Analysis for Determining Ratchet, Shakedown and Elastic Limits

2011 ◽  
Author(s):  
Jeries Abou-Hanna ◽  
Michael Paluszkiewicz
Keyword(s):  
Finite Element ◽  
Cyclic Load ◽  
Complex Geometry ◽  
Limit Load ◽  
Automated Analysis ◽  
Numerical Approach ◽  
Material Behavior ◽  
Element Analysis ◽  
Daunting Task ◽  
Elastic Shakedown

In order to determine the ratchet and shakedown limit curves for even a simple component, such as a tube under a constant pressure load and cyclic thermal load, can be a daunting task when using conventional analysis methods (elasto-plastic cyclic finite element analysis) that require repeated iterative simulations to determine the state of the structure, elastic, shakedown, plastic or ratchet. In some cases, the process is further complicated by the difficulty in interpreting results of the cyclic loading to determine in which regime the structure is. Earlier work by Abou-Hanna and McGreevy was able to demonstrate limit load analysis of a structure whose yield strength is modified based on cyclic load, provided the ratchet limit [1]. The method, called Anisotropic Load Dependent Yield Modification (LDYM), was implemented by using a user subroutine with ABAQUS, a general commercial finite element code. The approach adopted provided ratchet limits for only one individual cyclic load value. The work presented here describes a process for analyzing the structure and determining the elastic, shakedown and ratchet boundaries all in one finite element simulation using only one analysis step. The approach manipulates the structure material behavior that enables the resetting of the material characteristics to their original values in order to be able to analyze the structure for different sets of cyclic and primary load combinations. The process was verified using problems available in the literature, such as the Bree tube and Ponter’s Holed Plate. Additionally, a tubular T-joint was used as an example of the effectiveness of the process for a three dimensional complex geometry. The tubular T-joint results are verified against baseline data from the iterative elastic-plastic simulations used to determine the elastic, shakedown, and ratchet limits. The work presented highlights the advantages and limitations of this numerical approach which requires little interaction with the analyst.

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