Nebraska Data Collection

Automated pavement performance data collection is a method that uses advanced technology to collect detailed road surface distress information at traffic speed. Agencies are driven to use automated survey techniques to enhance or replace their current manual distress survey because of the advantages of objective measurements, safety benefits, and reduced measurement time. As agencies move toward the transition to fully automated data collection methods, there are common concerns regarding how the output of the new method will match the current manual survey ratings and how they will be adopted into the existing Pavement Management System (PMS). This study evaluates the newly implemented automated distress survey technique and its implementation into the Nebraska Pavement Management System (NPMS). To meet the objectives, a user-friendly program was developed to convert the automated distress ratings into the current manual distress ratings format. Then, a data set that includes more than 7,000 miles of distress data collected by the automated method was converted to the manual data format and compared to the most recent manual rating data of those sections to assess the agreement between the two data formats after the conversion process. The results show that the automated pavement survey slightly overrates bituminous pavement distresses with only a few distress types that could not be properly detected. Finally, a regression analysis of a core pavement performance indicator, NSI, was conducted to examine how the new automated performance measurement system will ultimately affect NPMS decisions if implemented into Nebraska’s pavement management system

MIDAS-VT-Pre: Software to generate 2D finite element model of particle/fiber embedded composites with cohesive zones

Studying the behavior of particle/fiber embedded composites has been a common and challenging problem in mechanics of materials area. Analysis of these materials can be effectively conducted by computational simulations such as finite element (FE) analyses. Creating a model that represents the actual microstructure of the composite is crucial to obtain a trustable result, but is often laborintensive. Microstructure Inelastic Damage Analysis Software (MIDAS) Virtual Tester Preprocessor (MIDAS-VT-Pre) was developed to facilitate construction of two-dimensional microstructure FE models of particle/fiber embedded composites. MIDAS-VT-Pre is able to insert automatically cohesive zone interface elements in the mesh structure in order to simulate crack initiation and propagation. This program is tailored to generate the FE model of standard mechanical test configurations that are frequently used in laboratory settings. The output of this program includes mesh structure and boundary conditions. This information can be used to run FE simulation (i.e. virtual testing) using common FE software such as ABAQUS

MIDAS-VT-Pre: Software to generate 2D finite element model of particle/fiber embedded composites with cohesive zones

Studying the behavior of particle/fiber embedded composites has been a common and challenging problem in mechanics of materials area. Analysis of these materials can be effectively conducted by computational simulations such as finite element (FE) analyses. Creating a model that represents the actual microstructure of the composite is crucial to obtain a trustable result, but is often labor- intensive. Microstructure Inelastic Damage Analysis Software (MIDAS) Virtual Tester Preprocessor (MIDAS-VT-Pre) was developed to facilitate construction of two-dimensional microstructure FE models of particle/fiber embedded composites. MIDAS-VT-Pre is able to insert automatically cohesive zone interface elements in the mesh structure in order to simulate crack initiation and propagation. This program is tailored to generate the FE model of standard mechanical test configurations that are frequently used in laboratory settings. The output of this program includes mesh structure and boundary conditions. This information can be used to run FE simulation (i.e. virtual testing) using common FE software such as ABAQUS

Multiscale Research Toward Resilient Civil Infrastructure

Infrastructure materials are generally composite in nature and consist of different phases. Despite their widespread use, the mechanisms behind their behavior are often not fully understood. The aim of this research is to develop the capability to predict the performance of infrastructure based on its components, thus eliminating the need for costly experimental tests. Such an objective requires thorough understanding of material properties at various length-scales and investigation of the linkage between each scale. This approach can lead to more optimized designs, sustainable performance and maximized public benefi

The global burden of cancer attributable to risk factors, 2010-19 : a systematic analysis for the Global Burden of Disease Study 2019

Background Understanding the magnitude of cancer burden attributable to potentially modifiable risk factors is crucial for development of effective prevention and mitigation strategies. We analysed results from the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2019 to inform cancer control planning efforts globally. Methods The GBD 2019 comparative risk assessment framework was used to estimate cancer burden attributable to behavioural, environmental and occupational, and metabolic risk factors. A total of 82 risk-outcome pairs were included on the basis of the World Cancer Research Fund criteria. Estimated cancer deaths and disability-adjusted life-years (DALYs) in 2019 and change in these measures between 2010 and 2019 are presented. Findings Globally, in 2019, the risk factors included in this analysis accounted for 4.45 million (95% uncertainty interval 4.01-4.94) deaths and 105 million (95.0-116) DALYs for both sexes combined, representing 44.4% (41.3-48.4) of all cancer deaths and 42.0% (39.1-45.6) of all DALYs. There were 2.88 million (2.60-3.18) risk-attributable cancer deaths in males (50.6% [47.8-54.1] of all male cancer deaths) and 1.58 million (1.36-1.84) risk-attributable cancer deaths in females (36.3% [32.5-41.3] of all female cancer deaths). The leading risk factors at the most detailed level globally for risk-attributable cancer deaths and DALYs in 2019 for both sexes combined were smoking, followed by alcohol use and high BMI. Risk-attributable cancer burden varied by world region and Socio-demographic Index (SDI), with smoking, unsafe sex, and alcohol use being the three leading risk factors for risk-attributable cancer DALYs in low SDI locations in 2019, whereas DALYs in high SDI locations mirrored the top three global risk factor rankings. From 2010 to 2019, global risk-attributable cancer deaths increased by 20.4% (12.6-28.4) and DALYs by 16.8% (8.8-25.0), with the greatest percentage increase in metabolic risks (34.7% [27.9-42.8] and 33.3% [25.8-42.0]). Interpretation The leading risk factors contributing to global cancer burden in 2019 were behavioural, whereas metabolic risk factors saw the largest increases between 2010 and 2019. Reducing exposure to these modifiable risk factors would decrease cancer mortality and DALY rates worldwide, and policies should be tailored appropriately to local cancer risk factor burden. Copyright (C) 2022 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY 4.0 license.Peer reviewe

MULTISCALE MODELING OF FRACTURE IN QUASI-BRITTLE MATERIALS USING BIFURCATION ANALYSIS AND ELEMENT ELIMINATION METHOD

Analyzing the fracture of heterogeneous materials is a complex problem, due to the fact that the mechanical behavior of a heterogeneous material is strongly dependent on a variety of factors, such as its microstructure, the properties of each constituent, and interactions between them. Therefore, these factors must be effectively taken into account for accurate analysis, for which the multiscale method has been widely used. In this scheme, the computational homogenization method is used to obtain the effective macroscopic properties of a heterogeneous material based on the response of a Representative Volume Element (RVE). The growth of damage in an RVE can be simulated by using common damage theories (such as formation of microcracks) and treated according to standard homogenization theories, which results in degradation of the effective mechanical properties of the material. In most cases, increasing the loading further causes microcracks to accumulate and to consequently form a localized band within the RVE, which may become sufficiently large as compared to the size of the RVE. Standard homogenization approaches have several theoretical shortcomings in dealing with localized RVE that bring into question their viability. This study aims to develop and implement methods to account for localization of RVE and then reflecting it as a discontinuity on the macroscale model within a two-way coupled multiscale framework. In the proposed method, localization of RVE is assessed by bifurcation analysis, which is performed on the anisotropic tangent stiffness tensor of the RVE. The anisotropic tangent stiffness tensor is obtained by separately applying normal and shear displacement boundary conditions on the damaged RVE at each time step. Once the bifurcation analysis meets the onset of weak discontinuity requirement, a discontinuity is inserted on the macroscale model. The element elimination method is used to simulate the discrete representation of cracks on the macroscale model. The entire algorithm was implemented in the form of a two-way linked multiscale code in FORTRAN. Additionally, certain examples were solved using the developed code to demonstrate the viability of the proposed method. The results show that this approach can successfully simulate fracture in a heterogeneous quasi-brittle material without losing its key microstructural details. Advisor: Prof. Yong-Rak Ki

MIDAS-VT-Pre: Software to generate 2D finite element model of particle/fiber embedded composites with cohesive zones

Studying the behavior of particle/fiber embedded composites has been a common and challenging problem in mechanics of materials area. Analysis of these materials can be effectively conducted by computational simulations such as finite element (FE) analyses. Creating a model that represents the actual microstructure of the composite is crucial to obtain a trustable result, but is often labor- intensive. Microstructure Inelastic Damage Analysis Software (MIDAS) Virtual Tester Preprocessor (MIDAS-VT-Pre) was developed to facilitate construction of two-dimensional microstructure FE models of particle/fiber embedded composites. MIDAS-VT-Pre is able to insert automatically cohesive zone interface elements in the mesh structure in order to simulate crack initiation and propagation. This program is tailored to generate the FE model of standard mechanical test configurations that are frequently used in laboratory settings. The output of this program includes mesh structure and boundary conditions. This information can be used to run FE simulation (i.e. virtual testing) using common FE software such as ABAQUS

Multiscale Modeling of Fracture in Quasi-Brittle Materials Using Bifurcation Analysis and Element Elimination Method

Analyzing the fracture of heterogeneous materials is a complex problem, due to the fact that the mechanical behavior of a heterogeneous material is strongly dependent on a variety of factors, such as its microstructure, the properties of each constituent, and interactions between them. Therefore, these factors must be effectively taken into account for accurate analysis, for which the multiscale method has been widely used. In this scheme, the computational homogenization method is used to obtain the effective macroscopic properties of a heterogeneous material based on the response of a Representative Volume Element (RVE). The growth of damage in an RVE can be simulated by using common damage theories (such as formation of microcracks) and treated according to standard homogenization theories, which results in degradation of the effective mechanical properties of the material. In most cases, increasing the loading further causes microcracks to accumulate and to consequently form a localized band within the RVE, which may become sufficiently large as compared to the size of the RVE. Standard homogenization approaches have several theoretical shortcomings in dealing with localized RVE that bring into question their viability. This study aims to develop and implement methods to account for localization of RVE and then reflecting it as a discontinuity on the macroscale model within a two-way coupled multiscale framework. In the proposed method, localization of RVE is assessed by bifurcation analysis, which is performed on the anisotropic tangent stiffness tensor of the RVE. The anisotropic tangent stiffness tensor is obtained by separately applying normal and shear displacement boundary conditions on the damaged RVE at each time step. Once the bifurcation analysis meets the onset of weak discontinuity requirement, a discontinuity is inserted on the macroscale model. The element elimination method is used to simulate the discrete representation of cracks on the macroscale model. The entire algorithm was implemented in the form of a two-way linked multiscale code in FORTRAN. Additionally, certain examples were solved using the developed code to demonstrate the viability of the proposed method. The results show that this approach can successfully simulate fracture in a heterogeneous quasi-brittle material without losing its key microstructural details

Multiscale Modeling of Fracture in Quasi-Brittle Materials Using Bifurcation Analysis and Element Elimination Method

Analyzing the fracture of heterogeneous materials is a complex problem, due to the fact that the mechanical behavior of a heterogeneous material is strongly dependent on a variety of factors, such as its microstructure, the properties of each constituent, and interactions between them. Therefore, these factors must be effectively taken into account for accurate analysis, for which the multiscale method has been widely used. In this scheme, the computational homogenization method is used to obtain the effective macroscopic properties of a heterogeneous material based on the response of a Representative Volume Element (RVE). The growth of damage in an RVE can be simulated by using common damage theories (such as formation of microcracks) and treated according to standard homogenization theories, which results in degradation of the effective mechanical properties of the material. In most cases, increasing the loading further causes microcracks to accumulate and to consequently form a localized band within the RVE, which may become sufficiently large as compared to the size of the RVE. Standard homogenization approaches have several theoretical shortcomings in dealing with localized RVE that bring into question their viability. This study aims to develop and implement methods to account for localization of RVE and then reflecting it as a discontinuity on the macroscale model within a two-way coupled multiscale framework. In the proposed method, localization of RVE is assessed by bifurcation analysis, which is performed on the anisotropic tangent stiffness tensor of the RVE. The anisotropic tangent stiffness tensor is obtained by separately applying normal and shear displacement boundary conditions on the damaged RVE at each time step. Once the bifurcation analysis meets the onset of weak discontinuity requirement, a discontinuity is inserted on the macroscale model. The element elimination method is used to simulate the discrete representation of cracks on the macroscale model. The entire algorithm was implemented in the form of a two-way linked multiscale code in FORTRAN. Additionally, certain examples were solved using the developed code to demonstrate the viability of the proposed method. The results show that this approach can successfully simulate fracture in a heterogeneous quasi-brittle material without losing its key microstructural details

Multiscale Research Toward Resilient Civil Infrastructure

Infrastructure materials are generally composite in nature and consist of different phases. Despite their widespread use, the mechanisms behind their behavior are often not fully understood. The aim of this research is to develop the capability to predict the performance of infrastructure based on its components, thus eliminating the need for costly experimental tests. Such an objective requires thorough understanding of material properties at various length-scales and investigation of the linkage between each scale. This approach can lead to more optimized designs, sustainable performance and maximized public benefi