Stress and Material Property Estimation in the Intervertebral Disc From MRI-Based Finite Strains

2013 ◽  
Author(s):  
Kent D. Butz ◽  
Deva D. Chan ◽  
Corey P. Neu ◽  
Eric A. Nauman
Keyword(s):  
Intervertebral Disc ◽  
Computational Modeling ◽  
Material Properties ◽  
Mechanical Characterization ◽  
Intervention Strategies ◽  
Non Invasive ◽  
Property Estimation ◽  
Level Of Understanding ◽  
Material Property Estimation

The ability to estimate stresses and material properties within the intervertebral disc (IVD) has potential to provide a greater level of understanding and insight in the study of disc degeneration as well as the development of effective intervention strategies. By integrating non-invasive MRI-based imaging methods with computational modeling, a more complete mechanical characterization of the IVD may be achieved, thereby eliminating the need to disturb the tissue or potentially alter the structure destructively.

scholarly journals Position-dependent mechanical characterization of the PBF-EB-manufactured Ti6Al4V alloy

2021 ◽  
Author(s):  
Daniel Kotzem ◽  
Alexandra Höffgen ◽  
Rajevan Raveendran ◽  
Felix Stern ◽  
Kerstin Möhring ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Material Properties ◽  
Mechanical Characterization ◽  
Industrial Applications ◽  
Fatigue Tests ◽  
Ti6al4v Alloy ◽  
Effective Diameter ◽  
Powder Bed Fusion ◽  
Powder Bed

AbstractBy means of additive manufacturing, the production of components with nearly unlimited geometrical design complexity is feasible. Especially, powder bed fusion techniques such as electron beam powder bed fusion (PBF-EB) are currently focused. However, equal material properties are mandatory to be able to transfer this technique to a wide scope of industrial applications. Within the scope of this work, the mechanical properties of the PBF-EB-manufactured Ti6Al4V alloy are investigated as a function of the position on the building platform. It can be stated that as-built surface roughness changes within building platform whereby highest surface roughness detected by computed tomography (Ra = 46.0 ± 5.3 µm) was found for specimens located in the front of the building platform. In contrast, no significant differences in relative density could be determined and specimens can be assumed as nearly fully dense (> 99.9%). Furthermore, all specimens are affected by an undersized effective diameter compared to the CAD data. Fatigue tests revealed that specimens in the front of the building platform show slightly lower performance at higher stress amplitudes as compared to specimens in the back of the building platform. However, process-induced notch-like defects based on the surface roughness were found to be the preferred location for early crack initiation.

scholarly journals Inverse-FEM Characterization of a Brain Tissue Phantom to Simulate Compression and Indentation

2012 ◽  
Vol 8 (16) ◽  
pp. 11-36 ◽  
Author(s):  
Elizabeth Mesa-Múnera ◽  
Juan F Ramírez–Salazar ◽  
Pierre Boulanger ◽  
John W Branch
Keyword(s):  
Model Parameters ◽  
Experimental Measurements ◽  
Surgical Simulators ◽  
Property Estimation ◽  
Tissue Phantom ◽  
Tissue Interactions ◽  
The Difference ◽  
Tissue Models ◽  
Material Property Estimation

The realistic simulation of tool-tissue interactions is necessary for the development of surgical simulators and one of the key element for it realism is accurate bio-mechanical tissue models. In this paper, we determined the mechanical properties of soft tissue by minimizing the difference between experimental measurements and the analytical or simulated solution of the deformation. Then, we selected the best model parameters that fit the experimental data to simulate a bonded compression and a needle indentation with a flat-tip. We show that the inverse FEM allows accurate material property estimation. We also validated our results using multiple tool-tissue interactions over the same specimen.

Research Survey of Electroformed Nickel Material Properties Used in MEMS

2015 ◽  
Vol 645-646 ◽  
pp. 259-264 ◽  
Author(s):  
Guo Zhong Li ◽  
Geng Chen Shi ◽  
Li Sui ◽  
Fu Ting Yi ◽  
Bo Wang
Keyword(s):  
Material Properties ◽  
Mechanical Characterization ◽  
External Environment ◽  
Structural Materials ◽  
Research Status ◽  
Research Survey ◽  
Electroforming Process ◽  
Electroformed Nickel ◽  
Materials Used

As one of the significant structural materials used in safe and arming system of MEMS fuze, the research on micro-electroforming process technologies and micro-electroforming nickel’s properties have been a popular field for MEMS area. This paper surveys present domestic and overseas research status of mechanical characterization of electroformed nickel, summarizes and analyzes that changes of the microstructure led by parameters of micro-electroforming process and the external environment make great effects.

scholarly journals Mechanical Characterization of Nanocrystalline Materials via a Finite Element Nanoindentation Model

Metals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1827
Author(s):  
Konstantinos Tserpes ◽  
Panagiotis Bazios ◽  
Spiros G. Pantelakis ◽  
Maria Pappa ◽  
Nikolaos Michailidis
Keyword(s):  
Material Properties ◽  
Nanocrystalline Materials ◽  
Mechanical Characterization ◽  
Numerical Technique ◽  
Nanoindentation Test ◽  
Inverse Algorithm ◽  
Average Grain Size ◽  
Alternative Means ◽  
Porosity Effect

The difficulty of producing sufficient quantities of nanocrystalline materials for test specimens has led to an effort to explore alternative means for the mechanical characterization of small material volumes. In the present work, a numerical model simulating a nanoindentation test was developed using Abaqus software. In order to implement the model, the principal material properties were used. The numerical nanoindentation results were converted to stress–strain curves through an inverse algorithm in order to obtain the macroscopic mechanical properties. For the validation of the developed model, nanoindentation tests were carried out in accordance with the ISO 14577. The composition of 75% wt. tungsten and 25% wt. copper was investigated by producing two batches of specimens with a coarse-grain microstructure with an average grain size of 150 nm and a nanocrystalline microstructure with a grain diameter of 100 nm, respectively. The porosity of both batches was derived to range between 9% and 10% based on X-ray diffraction analyses. The experimental nanoidentation results in terms of load–displacement curves show a good agreement with the numerical nanoindentation results. The proposed numerical technique combined with the inverse algorithm predicts the material properties of a fully dense, nanocrystalline material with very good accuracy, but it shows an appreciable deviation with the corresponding compression results, leading to the finding that the porosity effect is a crucial parameter which needs to be taken into account in the multiscale numerical methodology.

Microtensile Methodology for Mechanical Characterization of Thin Films

2001 ◽  
Author(s):  
Betty H. Yeung ◽  
Bill Lytle ◽  
Vijay Sarihan ◽  
David T. Read ◽  
Yifan Guo
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Material Properties ◽  
Mechanical Characterization ◽  
Technology Development ◽  
Metal Films ◽  
Metallic Films ◽  
Information Base ◽  
Constitutive Properties

Abstract A microtensile methodology developed at the National Institute of Standards and Technology (NIST) has been adopted and applied at Motorola to evaluate material properties of thin films. This methodology is a significant part of the materials technology development at Motorola. Special specimens of thin metal films are designed and produced based on common microlithographic techniques and silicon processing methods. The experimentation is performed using the microtensile tester, which was developed for the accurate measurement of constitutive properties of thin metallic films. Through the application of the techniques presented here, valuable information and results have been achieved, which provide an extended information base for thin-film materials. Ultimately, such data are applied to processing and reliability predictions and the optimization of thin-film processes and materials.

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