Damage Prediction Method Research Articles

A case study on rock damage prediction and control method for underground tunnels subjected to adjacent excavation blasting

The effects of tunnel blast excavation on the surrounding rock mass and the lining systems of adjacent existing tunnels are comprehensively studied for the Damaoshan highway tunnel project as a case study. The damage of the surrounding rock and the lining system under different blast loads are analyzed by field tests and numerical simulations. It is observed that the rock damage extent around the tunnels linearly increases with the peak particle velocity (PPV) of the existing tunnel. A feasible PPV-based damage control method is then proposed for different portions of the tunnels. For the Damaoshan tunnel project, a PPV threshold of 0.22m/s in the adjacent existing tunnel is prescribed to limit the damage extent to approximately 1.6m at the tunnel exit and entrance portions. Furthermore, the PPV criteria for the other portions are also determined accordingly. It is also shown that no failure occurs in the linings or at the rock–lining interfaces if the PPV is less than 0.30m/s. The control method and the threshold PPV proposed in this study have been successfully applied to restrict blast-induced damage during the new tunnel excavation of the Damaoshan tunnel project.

Constitutive Modeling of Multistage Creep Damage in Isotropic and Transversely Isotropic Alloys With Elastic Damage

In the pressure vessel and piping and power industries, creep deformation has continued to be an important design consideration. Directionally solidified components have become commonplace. Creep deformation and damage is a common source of component failure. A considerable effort has gone into the study and development of constitutive models to account for such behavior. Creep deformation can be separated into three distinct regimes: primary, secondary, and tertiary. Most creep damage constitutive models are designed to model only one or two of these regimes. In this paper, a multistage creep damage constitutive model is developed and designed to model all three regimes of creep for isotropic materials. A rupture and critical damage prediction method follows. This constitutive model is then extended for transversely isotropic materials. In all cases, the influence of creep damage on general elasticity (elastic damage) is included. Methods to determine material constants from experimental data are detailed. Finally, the isotropic material model is exercised on tough pitch copper tube and the anisotropic model on a Ni-based superalloy.

Predicting the risk of wild boar damage to rice paddies using presence-only data in Chiba Prefecture, Japan

Population sizes of wild boar (Sus scrofa) and the damage they cause to crops have been increasing in Japan. Reliable techniques are needed to estimate the potential for damage at the landscape scale. Here, we predict the risk of damage to rice (Oryza sativa) paddies by wild boar in Chiba Prefecture, Japan, by means of three different modelling methods – Maxent, generalised linear model (GLM) and generalised additive model (GAM) – using a combination of presence-only damage data obtained from a local agency and environmental information derived from publicly available databases. We used damage locations in 2007 and 2008. To validate the models, we calculated the area under the curve (AUC) and the correct classification rate (CCR) using independent data obtained in field surveys. The three methods gave similar results, indicating that we could construct a predictive model with high accuracy from presence-only data. Among these three, Maxent showed the closest fit, with 0.78 AUC and 72.6% CCR values. Because it is important to estimate the risk of damage to reduce future damage and costs, these damage prediction methods using presence-only data, which administrative agencies can obtain with no cost, this could assist local governments in formulating damage control plans.

東北地方太平洋沖地震津波による浸水域被害と構造物被害予測法

東北地方太平洋沖地震津波による浸水域被害と構造物被害予測法

Evaluation of fatigue and rut damage prediction methods for asphalt concrete pavements subjected to multiple axle loads

The new Mechanistic–Empirical Pavement Design Guide (MEPDG) developed under NCHRP 1-37A does away with the American Association of State Highway and Transportation Officials-derived equivalent single axle load concept and calculates damage caused by various axle configurations directly. However, the calculation of pavement damage caused by multiple axles (tandem, tridem, etc.) is significantly affected by the summation method used to describe the response of the pavement due to the passage of a given axle type or truck configuration. In this paper, the results from different methods of accounting for the passage of a given axle group are compared using laboratory fatigue and rut data from repeated cyclic load tests. The evaluation criterion for these different summation methods was the degree of agreement with the measured laboratory performance. The results show that for fatigue damage, dissipated energy and strain area methods have an excellent agreement with the laboratory values, whereas peak and peak mid-way methods have poor agreement. This implies that it is important to consider the entire strain pulse when calculating fatigue damage under multiple axles. For rutting damage, the peak strain method has the best agreement with the laboratory values, whereas dissipated energy and peak mid-way methods underestimate the rutting damage. Finally, the MEPDG procedure for calculating the strain under multiple axles considerably underestimates the damage for both fatigue and rutting. However, model calibration in the MEPDG does improve the prediction of the damage due to multiple axles for fatigue and to a lesser extent for rutting.

Void Nucleation Model in a Steam Turbine Material under Creep Condition

In order to establish a reliable remaining life assessment method for high temperature components in thermal power plants, it is necessary to understand the internal damage mechanism in heat resistant alloys and establish the damage prediction method. In the case of commercial heat resistant alloy used for thermal plants, nucleation, growth and coalescence of creep voids are dominant damage mechanism. So far, the void growth mechanism is well investigated and various growth models are suggested. However, rational modeling of void nucleation was remained to be difficult subject because basic mechanism has been unclear. Therefore, in this study, void nucleation behavior of a turbine rotor material under creep condition was investigated by a scanning electron microscope and development of void nucleation models was examined. Void nucleation model was developed based on the idea that creep voids nucleate by vacancy condensation at the interface between precipitated carbides and matrix on the grain boundary. In addition, consideration of creep property was included in the model via a relationship between strain and vacancy density obtained from the molecular mechanics simulation. In addition, model was expanded to predict the void number density, by a statistical treatment of the different physical property related to void nucleation in the every grain boundary. It was confirmed that the present void nucleation model can reproduce evolution of void number density.

Bird strike damage analysis in aircraft structures using Abaqus/Explicit and coupled Eulerian Lagrangian approach

The subject of this paper is numerical prediction of bird strike induced damage in real aeronautical structures using highly detailed finite element models and modern numerical approaches. Due to the complexity of today’s aeronautical structures, numerical damage prediction methods have to be able to take into account various failure and degradation models of different materials. A continuum damage mechanics approach has been employed to simulate failure initiation and damage evolution in unidirectional composite laminates. Hashin’s failure initiation criteria have been employed in order to be able to distinct between four ply failure modes. The problem of soft body impacts has been tackled by applying the Coupled Eulerian Lagrangian technique, thereby avoiding numerical difficulties associated with extensive mesh distortion. This improvement in impactor deformation modelling resulted in a more realistic behaviour of bird material during impact. Numerical geometrical and material nonlinear transient dynamic analyses have been performed using Abaqus/Explicit. The main focus of the work presented in this paper is the application of the damage prediction procedure in damage assessment of bird impact on a typical large airliner inboard flap structure. Due to the high cost of gas-gun testing of aircraft components, experimental testing on the real flap structure could not have been performed. In order to evaluate the accuracy of the presented method, the bird and composite damage model have been validated against experimental data available in the literature.

A Method for Earthquake Damage Prediction of Building Group Considering Building Vulnerability Classification

In this paper, the vulnerability of the multi-storey reinforced concrete is classified and analyzed according to three control factors: construction age, story and uses. And the different categories vulnerability matrices of multi-story reinforced concrete are obtained from the monomer sample buildings which are already evaluated. The proportion of construction area of different categories can be attained from buildings census statistics. Then the vulnerability matrix of concrete building group in study region can be established by sum-product of construction area ratio of each vulnerability class in study region and each class vulnerability matrix. Finally, the vulnerability matrix of reinforced concrete structure of Xi'an Yanliang District was obtained using this approach. After comparing with the traditional earthquake damage prediction method, it is shown that this method is feasible, simple idea and high reliable and can be used for rapid assessment of post earthquake.

Hurricane Damage and Loss Estimation Using an Integrated Vulnerability Model

An integrated vulnerability model is presented to estimate structural damage and related economic losses in clusters of residential buildings resulting from hurricane winds. The model accounts for the occurrence of a possible “chain reaction” of events involving wind-pressure damage and wind-borne debris damage, amplifying overall losses. Different approximate damage and loss prediction methods are compared, and three numerical examples are provided.

Damage prediction for magnesium matrix composites formed by liquid-solid extrusion process based on finite element simulation

A damage prediction method based on FE simulation was proposed to predict the occurrence of hot shortness cracks and surface cracks in liquid-solid extrusion process. This method integrated the critical temperature criterion and Cockcroft & Latham ductile damage model, which were used to predict the initiation of hot shortness cracks and surface cracks of products, respectively. A coupling simulation of deformation with heat transfer as well as ductile damage was carried out to investigate the effect of extrusion temperature and extrusion speed on the damage behavior of C sf/AZ91D composites. It is concluded that the semisolid zone moves gradually toward deformation zone with the punch descending. The amplitude of the temperature rise at the exit of die from the initial billet temperature increases with the increase of extrusion speed during steady-state extrusion at a given punch displacement. In order to prevent the surface temperature of products beyond the incipient melting temperature of composites, the critical extrusion speed is decreased with the increase of extrusion temperature, otherwise the hot shortness cracks will occur. The maximum damage values increase with increasing extrusion speed or extrusion temperature. Theoretical results obtained by the Deform™-2D simulation agree well with the experiments.

An Explicit Numerical Modeling of Soft Body Impact Damage in Metallic Airplane Structures

This paper tackles the problem of numerical prediction of bird strike induced damage in real aeronautical structures using highly detailed finite element models and modern numerical approaches. Due to the complexity of today’s aeronautical structures, numerical damage prediction methods have to be able to take into account various failure and degradation models of different materials. The work presented in this paper is focused on damage modeling in metallic items of aeronautical structures. Abaqus/Explicit has been employed to perform geometrical and material nonlinear transient dynamic analyses. The problem of soft body impacts has been tackled by applying a hybrid Eulerian Lagrangian technique, thereby avoiding numerical difficulties associated with extensive mesh distortion. Eulerian modeling of the bird impactor resulted in a more realistic behavior of bird material during impact. The main focus of the work presented in this paper is the application of damage prediction procedure in damage assessment of bird impact on a typical large airliner slat structure and comparison with damage observed during exploitation of a real slat structure. Due to the high cost of gas-gun testing of aircraft components, experimental testing on the real flap structure could not have been performed. Validation of the hybrid formulation in solving bird strike problems has been achieved by comparison with available references.

Cyclic testing and numerical modelling of carbon steel and stainless steel tubular bracing members

In order to study the cyclic response of tubular bracing members of three structural materials–hot-rolled carbon steel, cold-formed carbon steel and cold-formed stainless steel–a total of 16 square and rectangular hollow section members were tested under cyclic axial loading. The load–displacement hysteretic response, compressive resistance, lateral deflection, energy dissipation and fracture life of the specimens of these three materials were investigated. In addition, finite element models, verified against the experimental results from the current study and two other research programmes, were used in conjunction with a strain-based damage prediction method to conduct parametric studies. It is shown that existing empirical expressions for predicting the buckling resistance, post-buckling compressive strength and mid-length lateral deflections can be applied to both carbon steel and stainless steel specimens. However, the relationships between member ductility and slenderness are not representative over the full slenderness range, and are not applicable to cold-formed stainless steel members. New relationships, one for each material, are proposed to take into account the inter-relationship between global slenderness and local slenderness. The tangent stiffness throughout the loading cycle, which differed between the three materials, is found to be a crucial factor in determining the resistance to local buckling and number of cycles to failure of the braces.

Damage monitoring of refractory wall in a generic entrained-bed slagging gasification system

The main cause of performance degradation in entrained-bed slagging gasification systems is attributed to evolution of structural damage in the refractory walls. Early detection of such damage is necessary to avert unscheduled shutdown of a gasification plant. This paper develops an integrated computer simulation model of a generic entrained-bed slagging gasifier for formulation of a damage prediction algorithm with the objective of real-time degradation monitoring and condition-based maintenance of refractory walls. The integrated simulation model yields: (a) quasi-steady-state spatial temperature profiles at any cross-section of the gasification system, and (b) dynamic response of the refractory wall temperature that is measured by an array of sensors installed at specified locations on the external surface of the gasifier wall. The key idea for early detection of refractory-wall damage is built upon the fact that a local anomaly (i.e. deviation from the nominal condition) is likely to influence the temperature gradient in the refractory wall due to changes in the thermal impedance. The information from dynamic response of refractory temperature is extracted in a compressed form as statistical patterns of evolving anomaly through usage of a recently reported data-driven pattern identification tool called symbolic dynamic filtering (SDF). The results of this model-based investigation show that the proposed anomaly detection and damage prediction method is potentially capable of characterizing the health status of refractory walls in particular and the entire gasification system in general. The SDF algorithms in this paper are implemented on the MATLAB platform and are interfaced with the gasification plant simulation model for emulation of real-time degradation monitoring.

A simplified grounding damage prediction method and its application in modern damage stability requirements

This paper presents the analyses and results aimed at developing damage stability requirements which take into account the structural vulnerability to grounding damage, i.e. the kinetic energy available to generate damage and the structural resistance. The paper presents analysis of new damage statistics in order to determine impact scenarios, in particular in terms of impact speed, impact location, and width and height of damage. Furthermore a new empirical damage prediction formula is developed based on a combination of full-scale testing and extensive non-linear finite element analyses. This deterministic prediction method is validated against grounding experiments and then used in a probabilistic (Monte Carlo) simulation framework. First the simulation method is calibrated and validated against the real statistical damage data for conventional ships and then it is used to generate damage statistics for high-speed craft. It turns out that the grounding damage statistics for all ships can be characterized by a single parameter; the Grounding Damage Index, GDI, which includes the ship kinetic energy and its structural resistance to grounding damage. Simple, closed-form expressions are developed for the GDI and it is shown how the probability of exceeding a box-shaped damage is a simple function of the GDI and the size of the box. The paper therefore gives the background and the results for a new generation of damage stability rules where the structural crashworthiness is taken into account and where the passive safety level is explicitly expressed. It furthermore gives simplified prediction tools and data for actual ships, i.e. a toolbox that is readily available for risk analysis regarding grounding damage.

Improvement of Prediction Method of Coastal Damage due to Tsunami

The following improvements on tsunami damage predicting are examined in order to decrease the tsunami damage: 1) It is checked that the destructive evaluation of buildings of a wide area due to tsunami can be efficiently performed with the numerical model which can calculate a flood of only land area with good accuracy and the gate type Rahmen model. 2) The limit of inundation height that human-beings can stand up to tsunami is obtained using data of a large-scale model experiment. This limit is determined by a slide and changes in the range of 20cm-40cm with sex and height. 3) When the overflow of tsunami occurs on the land area of a steep slope, a strong back-flow will occur. Therefore, a calculating method which can be used for the stable examination against it is also proposed.

鋼構造ハンチ付き梁およびRBS梁の必要変形性能に関する研究

It is crucial to establish method evaluating ductility demand of beams for seismic design of structures. However, there are few studies on the demand of haunched beams and reduced section beam (internal plastic hinge beams) in steel moment resisting frames subjected to severe earthquakes. This paper proposes a damage prediction method of internal hinge beams based on energy equilibrium, and confirms applicability of the method. By applying the proposed method, the difference in damage between internal hinge beams and ordinary beams has been quantitatively clarified, and it can be concluded that the ductility demand of the former beams is not more than the the demand for the latter beams.

Damage mechanism in weldment of 2.25Cr–1Mo steel under creep–fatigue loading

The purpose of this study is to clarify damage process of “Type IV cracking” in weldment of a 2.25Cr–1Mo steel and to propose a micro damage prediction method. From continuous observation under a creep–fatigue test, it was found that spherical shape voids initiated and grew on grain boundaries in fine grain region and these voids grow continuously by changing their shape to crack-like. Both spherical and crack-like void growth rate equations were derived from the proposed void growth model. It was indicated that measured void growth rate under the creep–fatigue loading was well predicted by the growth rate equations.

EFFECTS OF MULTIPLE DETONATIONS ON THE DAMAGE OF REINFORCED CONCRETE SLABS

In this study, effects of multiple detonations on reinforced concrete (RC) slabs has been experimentally investigated to improve design and damage estimation methods of RC shelters. One of main results obtained is that crater and spall depths of the RC slab for a double detonation may be relatively well predicted by modifying our damage prediction method, which was previously applied to a virgin RC slab subjected to a single detonation.

鍛造用金型の損傷評価技術に関する研究

Recently, warm forging process takes the place of hot forging process gradually, for example, in manufacturing CVJ. However, die damage is serious problem in warm forging process with large expansion of surface of work piece, because it is not inquired enough. Though trying to extend die life by means of FEM analysis, it dose not play an enough role, because there is few method to evaluate die damage in warm forging condition. The test of Pin-on-disk and Ogoshi wear out can not be also applied to the method of die damage of warm forging process. In this study, we have established new test which could systematically evaluate die damage in warm forging process. And we have examined forging condition in warm forging process about quality of die and cooling system of die. This test aims at utilizing for establishment of simulation engineering of die damage prediction and quantitative evaluation method.

EFFECTS OF MULTIPLE DETONATIONS ON THE DAMAGE OF REINFORCED CONCRETE SLABS

In this study, effects of multiple detonations on reinforced concrete (RC) slabs has been experimentally investigated to improve design and damage estimation methods of RC shelters. One of main results obtained is that crater and spall depths of the RC slab for a double detonation may be relatively well predicted by modifying our damage prediction method, which was previously applied to a virgin RC slab subjected to a single detonation.