Effect Of Material Damage Research Articles

Assessing the role of socio-demographic characteristics, social support and formal disaster assistance in predicting the subjective recovery of flood survivors in Pakistan

ABSTRACT This article investigates the effects of socio-demographic characteristics of the 2010 flood victims, their flood exposure, and social and formal support on post-flood subjective recovery. It seeks to illuminate the factors best correlating with life recovery feelings of the respondents. Regression analysis of survey data showed that period of return to home, annual income, family size, material damage, and social support significantly correlated with the life recovery of respondents. More specifically, the period of return to home and material loss had a negative connection with life recovery feelings of flood victims while the annual income of the respondents, family size, and social support had a positive correlation on their life recovery feelings. Analysis also revealed that formal disaster support had a very negligible correlation with life recovery. However, social support helped to lessen the negative effects of material damage on the life recovery feelings of the survivors. The correlation of annual income with life recovery feelings remained almost constant and significant in all the regression models, showcasing the importance of personal resources to recover from disaster. The study concludes that although both social and formal support are pivotal for post-flood subjective recovery, they face serious limitations. More nuanced longitudinal studies are required to understand the contours of long-term life recovery process.

A Combined Experimental and Numerical Calibration Approach for Modeling the Performance of Aerospace-Grade Titanium Alloy Products

Finite element modeling for designing and optimizing lightweight titanium aerospace components requires advanced simulation tools with adequate material modeling. In this sense, a hybrid strategy is proposed in this work to identify the parameters of the Johnson–Cook plasticity and damage laws using a combined direct-inverse method. A direct calibration method for plasticity law is applied based on the literature-reported data of strain-stress curves from experimental tensile tests at different temperatures and strain rates. The triaxiliaty-dependent fracture parameters of the Johnson–Cook damage law at reference conditions of strain rate and temperature (d1, d2, and d3) are calibrated with the direct method based on new data of experimental evolution of computed average fracture strain with the average stress triaxiality. The validation is performed with numerical results from an accurate micromechanics-based Ti64 model. The inverse calibration method is used to determine the strain rate and temperature-dependent damage parameters (d4 and d5) through large strain simulations of uniaxial tensile tests. The numerical results, including average strain and necking profile at fracture, are then utilized to calculate stress triaxiality by the Bridgman criterion for adjusting parameters d4 and d5. The calibrated model yields a 2.1% error for plasticity and 3.4% for fracture predictions. The experimental and simulated load-bearing capacity using the micromechanics damage model differed by only 1%. This demonstrates that the SC11–TNT model of Ti64 is reliable for identifying the Johnson–Cook damage law through the accurate use of inverse methods. The hybrid calibration strategy demonstrates the potential capability of the identified Johnson–Cook model to accurately predict the design load-carrying capacity of Ti64 aerospace components under different deformation rates and temperatures while accounting for material damage effects.

ANALYSIS OF CORD–RUBBER COMPOSITE RESPONSE BY USING THE NONLINEAR CONTINUUM DAMAGE MECHANICS APPROACH

ABSTRACT The phenomenon of damage observed in cord–rubber composite laminates is the result of deformation, heat, chemical damage, and fracture. The micro cracks and the initial voids, present before any load is applied, grow through the mechanism of coalescence and generate permanent macroscopic cracks. A damage approach is proposed to describe the cumulative effects and damage evolution under cyclic loading and thermal and chemical impact. The approach parallels the continuum damage mechanics approach advocated by Kachanov and Rabotnov.1,2 It is a phenomenological model that depends on laboratory testing to describe the evolution of damage and contains one scalar parameter to describe the collective effect of material damage. The following analysis is based on the premise that the cyclic interlaminar shear strain, coupled with the running temperature at the free edge, is the primary cause of damage. The model constants were derived from an alternating stress (S) against the number of cycles to failure (N) (i.e., S-N) curve at room temperature. The temperature effect on the material damage was accounted for by an Arrhenius shift function of the S-N curve. Numerical simulation of a composite laminate was conducted using the user subroutine UMAT in ABAQUS. The results presented reflect the accuracy of the proposed methodology to predict the location of the ensuing damage and the path of the damage propagation.

Shape optimization of concrete free-form shells considering material damage

Shape optimization is a pervasive tool for designing concrete free-form shells. However, the existing shape optimization approaches for free-form shells usually assume the material is purely elastic without considering material damage, which may produce undesired results in real-world structural applications, especially in the case of concrete structures. In this article, a framework is presented for performing the shape optimization of concrete free-form shells while considering concrete damage. In the proposed optimization algorithm, the Mazars model is coupled with finite element analysis for modelling structural responses subjected to material damage. Through a series of numerical examples, the proposed algorithm is validated and the effects of material damage on optimal results are investigated. It is demonstrated that the consideration of material damage leads to a more robust design, which highlights the importance of accounting for the material damage during the shape optimization process of concrete free-form shells.

Molecular dynamics investigation of threshold displacement energies in CaF2

Understanding the propagation of radiation damage in a material is paramount to predicting the material damage effects. To date, no current literature has investigated the Threshold Displacement Energy (TDE) of Ca and F atoms in CaF2 through molecular dynamics and simulated statistical analysis. A set of interatomic potentials between Ca-Ca, F-F, and F-Ca were splined, fully characterizing a pure CaF2 simulation cell, by using published Born-Mayer-Huggins, standard ZBL, and Coulomb potentials, with a resulting structure within 1% of standard density and published lattice constants. Using this simulation cell, molecular dynamics simulations were performed with LAMMPS using a simulation that randomly generated 500 Ca and F PKA directions for each incremental set of energies, and a simulation in each of the [1 0 0], [1 1 0], and [1 1 1] directions with 500 trials for each incremental energy. MD simulations of radiation damage in CaF2 are carried out using F and Ca PKAs, with energies ranging from 2 to 200 eV. Probabilistic determinations of the TDE and Threshold Vacancy Energy (TVE) of Ca and F atoms in CaF2 were performed, as well as examining vacancy, interstitial, and antisite production rates over the range of PKA energies. Many more F atoms were displaced from both PKA species, and though F recombination appears more probable than Ca recombination, F vacancy numbers are higher. The higher number of F vacancies than Ca vacancies suggests F Frenkel pairs dominate CaF2 damage.

Finite element study of headed shear studs embedded in ultra-high performance concrete

A novel bridge repair method has been developed to strengthen steel bridge girders with section loss due to end corrosion. The repair comprises of welding headed shear studs to the non-corroded portion of the web plate and encasing them in ultra-high performance concrete (UHPC) to create an alternate bearing load path. The interaction between the headed studs and the UHPC panels is crucial in the force transfer. Therefore, a careful study is needed through high-fidelity finite element analysis to complement the experimental results. This paper presents the development of a model in Abaqus finite element software that enables capturing the behavior of studs embedded in UHPC. The model was validated using a series of experimental results from push-out tests with headed shear studs welded onto a thin web plate. Experimental results from push-out tests performed on stud diameters of 12, 16 and 19 mm and two levels of eccentric loadings were used to calibrate the modeling methodology. The model explicitly considers effects of material damage, contact between the studs and UHPC, and the precise geometry of the weld collar of studs. After validation, design parameters such as interaction of in-plane torsion and direct shear, and limits for web thickness-to-stud diameter ratio were studied to compliment the experimental data. The results are expected to inform engineers about the design of this novel repair method. In addition, this paper may enable future finite element studies on the performance of studs in UHPC.

Mesoscale simulations of radiation damage effects in Materials: A SEAKMC perspective

Radiation damage presents a unique challenge for material simulations, with processes ranging from picoseconds to decades in time and nanometers to meters in length. Particularly, the understanding of many processes and fundamental mechanisms at the mesoscale are still lacking. In this paper, the self-evolving kinetic Monte Carlo (SEAKMC) method and its application to study mesoscale defect interaction is presented. SEAKMC is an off-lattice atomistic kinetic Monte Carlo approach which conducts ‘on-the-fly’ saddle point searches (SPS) using selective active volumes. The main components of SEAKMC are examined with focus on the comparative benefits of this method. Future areas of improvement are outlined, including suggestions for general improvements to SPS methods by reducing redundant searching and making predictive initial guesses for point defect migration events. Previous applications of SEAKMC to radiation effects in materials are briefly reviewed. Some potential applications of SEAKMC are given, including discussion of dislocation bias, and the further study of interaction between dislocation loops and point defects, which provide useful insights to understand void swelling, radiation induced segregation, and other important radiation damage processes.

A multiscale computational method with inheriting simulation of moving trans-scale boundary for damage-induced structural deterioration

PurposeThis paper aims to introduce a multiscale computational method for structural failure analysis with inheriting simulation of moving trans-scale boundary (MTB). This method is motivated from the error in domain bridging caused by cross-scale damage evolution, which is common in structural failure induced by damage accumulation.Design/methodology/approachWithin the method, vulnerable regions with high stress level are described by continuum damage mechanics, while elastic structural theory is sufficient for the rest, dividing the structural model into two scale domains. The two domains are bridged to generate mixed dimensional finite element equation of the whole system. Inheriting simulation is developed to make the computation of MTB sustainable.FindingsNumerical tests of a notched three-point bending beam and a steel frame show that this MTB method can improve efficiency and ensure accuracy while capturing the effect of material damage on deterioration of components and structure.Originality/valueThe proposed MTB method with inheriting simulation is an extension of multiscale simulation to structural failure analysis. Most importantly, it can deal with cross-scale damage evolution and improve computation efficiency significantly.

Experimental investigation of the effect of the material damage induced in sheet metal forming process on the service performance of 22MnB5 steel

The use of ultra-high strength steels through sheet metal forming process offers a practical solution to the lightweight design of vehicles. However, sheet metal forming process not only produces desirable changes in material properties but also causes material damage that may adversely influence the service performance of the material formed. Thus, an investigation is conducted to experimentally quantify such influence for a commonly used steel (the 22MnB5 steel) based on the hot and cold forming processes. For each process, a number of samples are used to conduct a uniaxial tensile test to simulate the forming process. After that, some of the samples are trimmed into a standard shape and then uniaxially extended until fracture to simulate the service stage. Finally, a microstructure test is conducted to analyze the microdefects of the remaining samples. Based on the results of the first two tests, the effect of material damage on the service performance of 22MnB5 steel is analyzed. It is found that the material damages of both the hot and cold forming processes cause reductions in the service performance, such as the failure strain, the ultimate stress, the capacity of energy absorption and the ratio of residual strain. The reductions are generally lower and non-linear in the former process but higher and linear in the latter process. Additionally, it is found from the microstructure analysis that the difference in the reductions of the service performance of 22MnB5 by the two forming processes is driven by the difference in the micro damage mechanisms of the two processes. The findings of this research provide a useful reference in terms of the selection of sheet metal forming processes and the determination of forming parameters for 22MnB5.

Влияние поврежденности материала на параметры крутильной волны, распространяющейся в деформируемом роторе

Влияние поврежденности материала на параметры крутильной волны, распространяющейся в деформируемом роторе

Effect of Material Damage on Parameters of a Torsional Wave Propagated in a Deformed Rotor

The proposed approach allows formulation formulating a self-consistent problem that includes an equation, describing rotor dynamics, and an equation, describing the damage to the material of the rotor. It is shown that the damage to the material causes frequency-dependent attenuation and phase speed dispersion of elastic torsion waves, which allows for the acoustic assessment of the damage. The applied field of deformations, in turn, leads to damage accumulation. The resulting kinetic equation shows that the increase in damage has exponential character. System parameters have been assessed, which makes it possible to consider the accumulation of damage linearly in time.

Experimental Investigation of Self-Sensing Carbon Fiber Reinforced Cementitious Composite for Strain Measurement of an RC Portal Frame

Traditional structural monitoring systems have disadvantages such as the shorter life span of sensors relative to that of the structure being monitored. The present study uses carbon fiber reinforced cementitious composite (CFRC) as a structural monitoring sensor to extend the life of a sensor to match that of the structure. There are some known advantages of CFRC, such as high tensile strength and high ductility that increase the seismic capacity and security of such structures. However, CFRC has functionality similar to piezoresistive materials, which can be used as self-sensing materials for strain measurement and damage detection. This property is based on the reversible effect of strain on the volume of electrical resistivity and the irreversible effect of material damage on its resistivity. Considering the economic benefits, the fiber content is only 0.2 vol.%, which is less than half of the amount used in other studies. The experimental results show that the conductivity of current materials is significantly improved by CFRC and that it can be used for strain measurement and damage detection. Moreover, the experimental results of CFRC-coated beams and the RC portal frame can be kept in a database for applications in structural health monitoring.

Computational modeling of the mechanical response of lightweight foamed concrete over a wide range of temperatures and strain rates

Theoretical and experimental studies on the nonlinear mechanical properties of lightweight foamed concrete under uniaxial compression are conducted over the temperature range of 223–343K and the strain rate range of 0.001–118/s in this paper. The experimental results show that the mechanical properties of the materials under uniaxial compression are strongly dependent on the density and temperature, but are weaker on strain rate. Based on the experimental results, the characteristics of density effect and temperature effect are analyzed and a calculation model is developed to describe the nonlinear mechanical behavior of lightweight foamed concrete. The model takes into account the effect of material damage, density and temperature. The experimental verification and the error analysis show that the model is shown to be able to predict the nonlinear deformation behavior of lightweight foamed concrete over a wide range of temperatures and densities.

Phonon contribution to nonionizing energy loss in silicon detectors**Supported by National Natural Science Foundation of China (11175223, 11305231, 11205220)

Nonionizing energy loss (NIEL) has been applied to a number of studies concerning displacement damage effects in materials and devices. However, most studies consider only the contribution of displacement damage effects, neglecting the contribution from phonons. In this paper, a NIEL model, which considers the contribution of phonons, has been established using the Monte Carlo code SRIM. The maximum endurable fluence for silicon detectors has been estimated using the equivalent irradiation fluence compared with experimental data for the incident particles. NIEL is proportional to the equivalent irradiation fluence that the detector has received.

State of the art for enhancing the blast resistance of reinforced concrete columns with fiber-reinforced plastic

Protective design has become a chief concern in the design of some bridges and buildings, particularly related to the requirement that such facilities offer protection from accidental or malicious explosions. In this paper, the enhancement of the blast-resistance capability of reinforced concrete columns using FRP (fiber-reinforced plastic) is examined as a key element in upgrading the protective design of existing buildings and bridges. In this paper, the basic behaviors that need to be considered in blast effects analysis of RC columns for vehicle bomb threats are described. The ability of FRP to address these sorts of risks is shown through the analysis and test results presented. Three crucial points are made: (1) FRP offers a remarkable capability to enhance the blast resistance of existing RC columns, (2) assessing the residual capacity of large columns struck by a blast loading involves consideration of the effects of material damage, and (3) physics-based material models are often needed to capture the concrete behaviors engendered by intense blast loads.

Displacement Damage Effects in Irradiated Semiconductor Devices

A review of radiation-induced displacement damage effects in semiconductor devices is presented, with emphasis placed on silicon technology. The history of displacement damage studies is summarized, and damage production mechanisms are discussed. Properties of defect clusters and isolated defects are addressed. Displacement damage effects in materials and devices are considered, including effects produced in silicon particle detectors, visible imaging arrays, and solar cells. Additional topics examined include NIEL scaling, carrier concentration changes, random telegraph signals, radiation hardness assurance, and simulation methods for displacement damage. Areas needing further study are noted.

Effect of material damage on the spallation threshold of single crystal copper: a molecular dynamics study

High velocity impact of copper plates using molecular dynamics has been performed to study the spallation of single crystal copper at impact velocities of 1100 and 1000 m s−1. The molecular dynamics code LAMMPS (Large-Scale Atomic/Molecular Massively Parallel Simulator) with the embedded atom method potential is used for this study. It is found that for an impact velocity of 1100 m s−1, nucleation and growth of multiple voids take place which lead to the spallation of the material. For the impact at 1000 m s−1 in the ⟨1 0 0⟩ impact direction, the material does not undergo spallation but gives a spall-like signal in the free surface velocity of the target. We show that the tension developed by first traversal of the shock wave creates various kinds of defects in the target. These become void nucleation sites during the subsequent traversal of the shock wave. The presence of void nucleation sites due to the first traversal of the shock leads to the nucleation of the voids at a lower tensile pressure. We also show that the spall-like signal in the free surface velocity of the target at 1000 m s−1 impact along the ⟨1 0 0⟩ direction occurs due to stress relaxation resulting from the nucleation and growth of the voids without physical separation of scab from the target.

Enforcement of multiscaling in energy dissipation based on local pico-/nano-/micro-structure properties

Unloading of uniaxial specimens is distinguished from the inherent process of self-dissipation energy in regions of non-homogeneity where material damage starts. Transfer of coupon test data to the design of large bodies differs fundamentally from the corresponding rules applied to small bodies with large ratios of surface to volume. Large bodies make use of bulk material properties whereas small bodies depend on the local properties that cannot be found by standard tests. The transitional region with high energy gradients must thus be delineated accordingly. The stiffness gradient criterion generally used for large bodies no longer applies to smaller bodies governed by different physical laws, a fact known to those work in nanotechnolgy associated with MEMS. When the size scale is refined, local inhomogeneity becomes dominant and cannot be averaged. Non-equilibrium thermodynamic behavior emerges and must be addressed accordingly. This overwhelming difficulty can be circumvented by adopting the scheme of multiscaling and segmentation for modeling progressive damage. That is by regarding a series of segmented damage initiation/termination processes which may consists of, say picocracking to nanocracking and nanocracking to microcracking followed by microcracking to macrocracking and so on. The ”crack tip” is ideal for showing the cause and effect of material damage because it has no dimension or mass to speak of and yet it can be regarded as the sink and source that absorb and dissipate energy, respectively. The processes of direct-absorption and self-dissipation energy activated by the crack tip will be considered as the manifestation of field inhomogeneity that can be modeled by isolated pockets of energy sinks and sources without loss in generality.The threshold for each scale range is assumed to depend on the square of the crack tip velocity ȧ2 and activated mass densities M↓↑ and M↓↑ such that W=M↓↑ȧ↑↓2 and D=M↓↑ȧ↑↓2. The quantities W and D are referred to, respectively, as the direct-absorption and self-dissipation energy density. They fluctuate in time and determine whether the surrounding crack tip field of inhomogeneity is expanding or contracting. Singularity representation is used to capture the smoothness character of the crack tip field strength while the discreteness is reflected by the characteristic length of each scale.Demonstrated will be a pico/nano/micro/macro fatigue cracking model of a 2024-T3 aluminum panel. Time degradation of the pico/nano/micro/macro material structure behavior is derived by using nine scale transitional physical parameters: three for the pico/nano range (μpi/na∗,σpi/na∗,dpi/na∗), three for the nano/micro range (μna/mi∗,σna/mi∗,dna/mi∗) and three for the micro/macro range (μmi/ma∗,σmi/ma∗,dmi/ma∗). The subscripts pi, na, mi and ma designate, respectively, pico, nano, micro, and macro. Only the ratios of two successive scale sensitive parameters need to be known. The time dependent physical parameters at the lower scale are implicit and needed only for analytical continuation.More specifically, the transitional character of picocracks, nanocracks, microcracks and macrocracks are determined from the specified life expectancy of time arrow according to pico→nano→micro→macro with the respective singularity strength of λ given by 1.25/1.00/0.75/0.50. Recall that λ=0.5 corresponds to the inverse square root r−0.5 in fracture mechanics with r being the distance from the macrocrack tip. The microcrack, nanocrack and picocrack tips are assigned with the singularities r−0.75 and r−1.00 and r−1.25, respectively. The time of arrow in years will depend on the problem definition. Progressive damage is assumed to occur in the direction of pico→nano→micro→macro. The same scheme is applied to the fatigue damage of a 2024-T3 panel with a total life time of 18.5+ to 20 years that may be distributed over the pico. nano, micro, macro and struc. scale according to 1.5+/2.5+/3.5+/5.5+/7.0+. Such a specification can only be satisfied by matching the energy dissipated in damaging the internal material structure at each scale range. Hence, the precise time dependent material property degradation process over the total life span can be enforced.

Prediction for forming limit of AL2024T3 sheet based on damage theory using finite element method

This paper presents the application of anisotropic damage theory to the study of forming limit diagram of Al2024T3 aluminum alloy sheet. In the prediction of limiting strains of the aluminum sheet structure, a finite element cell model has been constructed. The cell model consists of two phases, the aluminum alloy matrix and the intermetallic cluster. The material behavior of the aluminum alloy matrix is described with a fully coupled elasto-plastic damage constitutive equation. The intermetallic cluster is assumed to be elastic and brittle. By varying the stretching ratio, the limiting strains of the sheet under biaxial stretching have been predicted by using the necking criterion proposed. The prediction is in good agreement with the experimental findings. Moreover, the finite element cell model can provide information for understanding the microscopic damage mechanism of the aluminum alloy. Over-estimation of the limit strains may result if the effect of material damage is ignored in the sheet metal forming study.

Expansion and reduction of thin-walled tubes using a die: Experimental and theoretical investigation

The production of sound thin-walled tubular parts by expansion and reduction using a die is generally limited to components having geometrical features within a compact range. Basic design rules, providing the geometrical and material parameters that govern the process, are mainly derived from the accumulated experience of both manufacturers of tubular parts and suppliers of machine-tools. However, no information is generally available on the influence of interface friction on material flow and on the effect of material damage and strain path on the occurrence of fracture, wrinkling and local buckling. The aim of this paper is to refresh and extend the fundamentals of tube expansion and reduction using a die by means of a comprehensive theoretical and experimental investigation. The emphasis is focused on understanding modes of deformation and on establishing formability principles for the benefit of those who design tubular parts in daily practice. The theoretical investigation is accomplished by the utilization of virtual prototyping modelling techniques based on the finite element method and the experimental work is mainly utilized for supporting and validating the theoretical investigation.