Experimental data for validating the structural response of computational brain models

2022 ◽  
pp. 193-208
Author(s):  
A. Alshareef ◽  
J.S. Giudice ◽  
D. Shedd ◽  
K. Reynier ◽  
T. Wu ◽  
...  
Keyword(s):  
Experimental Data ◽  
Structural Response ◽  
Brain Models

Modelling the response of structure-tuned liquid damper systems under large amplitude excitation using SPH

2021 ◽  
pp. 1-31
Author(s):  
Kevin P. McNamara ◽  
Michael J. Tait
Keyword(s):  
Experimental Data ◽  
Large Amplitude ◽  
Numerical Models ◽  
Model Performance ◽  
Structural Response ◽  
System Response ◽  
Tuned Liquid Damper ◽  
Tall Structures ◽  
Incompressible Sph ◽  
Lower Excitation

Abstract The tuned liquid damper (TLD) is a system used to reduce the response of tall structures. Numerical modelling is a very important tool when designing TLDs. Many existing numerical models are capable of accurately capturing the structure-TLD system response at serviceability levels, covering the range where TLDs are primarily intended to perform. However, these models often have convergence issues when considering more extreme structural excitations. The goal of this study is to develop a structure-TLD model without convergence limitations at large amplitude excitations. A structure-TLD numerical model where the TLD is represented by a 2D incompressible SPH scheme is presented. The TLD contains damping screens which are represented by a force term based on the Morison equation. The performance of the model is assessed by comparing to experimental data for a structure-TLD system undergoing large amplitude excitations consisting of four-hour random signals and shorter transient signals. The model shows very good agreement with the experimental data for the structural response. The free surface response of the TLD is captured accurately by the model for the lower excitation forces considered, however as the excitation force is increased there are some discrepancies. The large amplitude excitations also result in SPH fluid particles penetrating the boundaries, resulting in degradation of the model performance over the four-hour simulations. Overall, the model is shown to capture the response of a structure-TLD system undergoing large amplitude excitations well.

Experimental Data Have to Decide Which of the Nonprobabilistic Uncertainty Descriptions—Convex Modeling or Interval Analysis—to Utilize

2008 ◽  
Vol 75 (4) ◽  
Author(s):  
Xiaojun Wang ◽  
Isaac Elishakoff ◽  
Zhiping Qiu
Keyword(s):  
Experimental Data ◽  
Interval Analysis ◽  
Structural Response ◽  
Main Idea ◽  
Minimum Volume ◽  
Analytical Treatment ◽  
Numerical Examples ◽  
Minimum Volume Ellipsoid ◽  
Nonprobabilistic Uncertainty ◽  
Existing Data

This study shows that the type of the analytical treatment that should be adopted for nonprobabilistic analysis of uncertainty depends on the available experimental data. The main idea is based on the consideration that the maximum structural response predicted by the preferred theory ought to be minimal, and the minimum structural response predicted by the preferred theory ought to be maximal, to constitute a lower overestimation. Prior to the analysis, the existing data ought to be enclosed by the minimum-volume hyper-rectangle V1 that contains all experimental data. The experimental data also have to be enclosed by the minimum-volume ellipsoid V2. If V1 is smaller than V2 and the response calculated based on it R(V1) is smaller than R(V2), then one has to prefer interval analysis. However, if V1 is in excess of V2 and R(V1) is greater than R(V2), then the analyst ought to utilize convex modeling. If V1 equals V2 or these two quantities are in close vicinity, then two approaches can be utilized with nearly equal validity. Some numerical examples are given to illustrate the efficacy of the proposed methodology.

scholarly journals Flexural Capacity of Steel Rack Connections Via The Component Method

2018 ◽  
Vol 12 (1) ◽  
pp. 90-100 ◽  
Author(s):  
Federico Gusella ◽  
Maurizio Orlando ◽  
Andrea Vignoli ◽  
Klaus Thiele
Keyword(s):  
Experimental Data ◽  
Mechanical Model ◽  
Structural Response ◽  
Experimental Tests ◽  
Materials Testing ◽  
Structural Behaviour ◽  
Component Method ◽  
Complementary Method ◽  
Fundamental Information ◽  
Geometric Layout

Background: In pallet rack structures, cold-formed steel (CFS) beams and columns are connected through dry joints, so beams can be easily disconnected according to changes of the rack geometric layout. Due to the great variety of connector types and member geometries, recent design codes recommend experimental tests on rack connections to assess their mechanical features. Nevertheless, tests only allow for the overall response of a joint to be evaluated, without providing information about the contribution of each component of the joint to its stiffness and strength. Objective: In this paper, a mechanical model is developed in order to provide useful information about the structural behaviour of rack beam-column connections. Methods: The proposed mechanical model is based on the application of the Component Method (CM) and it allows for the flexural resistance of steel rack connections to be analytically assessed. Analytical results are compared with experimental data from tests performed at the Structures and Materials Testing Laboratory of the Department of Civil and Environmental Engineering of Florence. Results: Results show a good agreement with experimental data, highlighting the accuracy of the proposed approach. The mechanical model allows for the weakest component of the joint and its failure mode to be evaluated, and it highlights the importance of an adequate welding between the beam-end section and the connector. Conclusion: The mechanical model provides fundamental information about the influence of structural details on the overall behavior of rack joints, it appears as a complementary method to expensive experimental tests and it can be used to improve the design of rack connections with the goal to increase their structural response.

scholarly journals Calibration of a Heterogeneous Brain Model Using a Subject-Specific Inverse Finite Element Approach

2021 ◽  
Vol 9 ◽  
Author(s):  
J. Sebastian Giudice ◽  
Ahmed Alshareef ◽  
Taotao Wu ◽  
Andrew K. Knutsen ◽  
Lucy V. Hiscox ◽  
...  
Keyword(s):  
Experimental Data ◽  
Finite Element ◽  
Magnetic Resonance ◽  
Human Brain ◽  
Template Model ◽  
Material Parameters ◽  
Material Heterogeneity ◽  
Subject Specific ◽  
Brain Models

Central to the investigation of the biomechanics of traumatic brain injury (TBI) and the assessment of injury risk from head impact are finite element (FE) models of the human brain. However, many existing FE human brain models have been developed with simplified representations of the parenchyma, which may limit their applicability as an injury prediction tool. Recent advances in neuroimaging techniques and brain biomechanics provide new and necessary experimental data that can improve the biofidelity of FE brain models. In this study, the CAB-20MSym template model was developed, calibrated, and extensively verified. To implement material heterogeneity, a magnetic resonance elastography (MRE) template image was leveraged to define the relative stiffness gradient of the brain model. A multi-stage inverse FE (iFE) approach was used to calibrate the material parameters that defined the underlying non-linear deviatoric response by minimizing the error between model-predicted brain displacements and experimental displacement data. This process involved calibrating the infinitesimal shear modulus of the material using low-severity, low-deformation impact cases and the material non-linearity using high-severity, high-deformation cases from a dataset of in situ brain displacements obtained from cadaveric specimens. To minimize the geometric discrepancy between the FE models used in the iFE calibration and the cadaveric specimens from which the experimental data were obtained, subject-specific models of these cadaveric brain specimens were developed and used in the calibration process. Finally, the calibrated material parameters were extensively verified using independent brain displacement data from 33 rotational head impacts, spanning multiple loading directions (sagittal, coronal, axial), magnitudes (20–40 rad/s), durations (30–60 ms), and severity. Overall, the heterogeneous CAB-20MSym template model demonstrated good biofidelity with a mean overall CORA score of 0.63 ± 0.06 when compared to in situ brain displacement data. Strains predicted by the calibrated model under non-injurious rotational impacts in human volunteers (N = 6) also demonstrated similar biofidelity compared to in vivo measurements obtained from tagged magnetic resonance imaging studies. In addition to serving as an anatomically accurate model for further investigations of TBI biomechanics, the MRE-based framework for implementing material heterogeneity could serve as a foundation for incorporating subject-specific material properties in future models.

Analysis of Adhesively Bonded Joints Between Panels of Composite Materials

1977 ◽  
Vol 44 (1) ◽  
pp. 101-106 ◽  
Author(s):  
W. J. Renton ◽  
J. R. Vinson
Keyword(s):  
Experimental Data ◽  
Mathematical Model ◽  
Orthotropic Material ◽  
Structural Response ◽  
Lap Joints ◽  
Bonded Joints ◽  
Excellent Correlation ◽  
Adhesively Bonded ◽  
Adhesively Bonded Joints ◽  
Material Systems

A mathematical model is developed and methods of analysis are formulated for determining the structural response of the single-lap and symmetric-lap joints composed of generally orthotropic material systems. Analytical results are compared in both instances with experimental data and excellent correlation is seen to exist.

On the Ballistic Impact of Textile Body Armor

1975 ◽  
Vol 42 (2) ◽  
pp. 263-268 ◽  
Author(s):  
J. R. Vinson ◽  
J. A. Zukas
Keyword(s):  
Experimental Data ◽  
Mathematical Model ◽  
Digital Computer ◽  
Structural Response ◽  
Ballistic Impact ◽  
Body Armor ◽  
Desk Calculator ◽  
Stepwise Procedure ◽  
Textile Fabric ◽  
Nylon Cloth

A mathematical model is developed and methods of analysis are formulated for determining the structural response of textile fabric flat panels subjected to ballistic impact by a dense projectile. A stepwise procedure in time is formulated which is suitable for either desk calculator use or for a digital computer in calculating strains, projectile position, forces, and decelerations as functions of time. Analytical results are compared with experimental data for impact of a .22 caliber fragment simulator impacting 1 ply and 12 ply nylon cloth as well as Kevlar (PRD)-49-IV cloth from 1–24 plies.

Microdiffraction Patterns of Small Metallic Particles II; Theoretical Analysis

1982 ◽  
Vol 40 ◽  
pp. 668-669
Author(s):  
A. Gómez ◽  
P. Schabes-Retchkiman ◽  
M. José-Yacamán ◽  
T. Ocaña
Keyword(s):  
Experimental Data ◽  
Electron Diffraction ◽  
Theoretical Analysis ◽  
Size Range ◽  
Dynamical Theory ◽  
Metallic Particles ◽  
Splitting Effect

The splitting effect that is observed in microdiffraction pat-terns of small metallic particles in the size range 50-500 Å can be understood using the dynamical theory of electron diffraction for the case of a crystal containing a finite wedge. For the experimental data we refer to part I of this work in these proceedings.

Evidence for ordered Fe3Ni

1987 ◽  
Vol 45 ◽  
pp. 216-217
Author(s):  
K.B. Reuter ◽  
D.B. Williams ◽  
J.I. Goldstein
Keyword(s):  
Experimental Data ◽  
Martensitic Transformation ◽  
Electron Diffraction ◽  
Room Temperature ◽  
Direct Evidence ◽  
Transformation Product ◽  
Iron Meteorites ◽  
X Ray ◽  
Ni Content ◽  
Temperature Transformation

In the Fe-Ni system, although ordered FeNi and ordered Ni3Fe are experimentally well established, direct evidence for ordered Fe3Ni is unconvincing. Little experimental data for Fe3Ni exists because diffusion is sluggish at temperatures below 400°C and because alloys containing less than 29 wt% Ni undergo a martensitic transformation at room temperature. Fe-Ni phases in iron meteorites were examined in this study because iron meteorites have cooled at slow rates of about 10°C/106 years, allowing phase transformations below 400°C to occur. One low temperature transformation product, called clear taenite 2 (CT2), was of particular interest because it contains less than 30 wtZ Ni and is not martensitic. Because CT2 is only a few microns in size, the structure and Ni content were determined through electron diffraction and x-ray microanalysis. A Philips EM400T operated at 120 kV, equipped with a Tracor Northern 2000 multichannel analyzer, was used.

EELS white line intensities calculated for the 3d and 4d metals

1989 ◽  
Vol 47 ◽  
pp. 388-389
Author(s):  
C. C. Ahn ◽  
D. H. Pearson ◽  
P. Rez ◽  
B. Fultz
Keyword(s):  
Experimental Data ◽  
Line Intensity ◽  
Transition Probabilities ◽  
Initial Increase ◽  
White Line ◽  
Hartree Fock ◽  
Line Intensities ◽  
Integrated Intensity ◽  
X Ray Absorption ◽  
The Continuum

Previous experimental measurements of the total white line intensities from L2,3 energy loss spectra of 3d transition metals reported a linear dependence of the white line intensity on 3d occupancy. These results are inconsistent, however, with behavior inferred from relativistic one electron Dirac-Fock calculations, which show an initial increase followed by a decrease of total white line intensity across the 3d series. This inconsistency with experimental data is especially puzzling in light of work by Thole, et al., which successfully calculates x-ray absorption spectra of the lanthanide M4,5 white lines by employing a less rigorous Hartree-Fock calculation with relativistic corrections based on the work of Cowan. When restricted to transitions allowed by dipole selection rules, the calculated spectra of the lanthanide M4,5 white lines show a decreasing intensity as a function of Z that was consistent with the available experimental data.Here we report the results of Dirac-Fock calculations of the L2,3 white lines of the 3d and 4d elements, and compare the results to the experimental work of Pearson et al. In a previous study, similar calculations helped to account for the non-statistical behavior of L3/L2 ratios of the 3d metals. We assumed that all metals had a single 4s electron. Because these calculations provide absolute transition probabilities, to compare the calculated white line intensities to the experimental data, we normalized the calculated intensities to the intensity of the continuum above the L3 edges. The continuum intensity was obtained by Hartree-Slater calculations, and the normalization factor for the white line intensities was the integrated intensity in an energy window of fixed width and position above the L3 edge of each element.

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