Journal articles: 'Spalling damage'

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Zhao, Jie, Jian Jun Zheng, and Gai Fei Peng. "Fire Spalling Modeling of High Performance Concrete." Applied Mechanics and Materials 52-54 (March 2011): 378–83. http://dx.doi.org/10.4028/www.scientific.net/amm.52-54.378.

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Under high temperature conditions, such as fire, high performance concrete will undergo material degradation or even spalling. Spalling is the most detrimental damage to concrete structures. To prevent concrete from spalling, the mechanism should be understood. In this paper, an anisotropic damage model, in which both the thermal stress and vapor pressure are incorporated, is presented to analyze the spalling mechanism. The spalling phenomenon is studied based on two cases of different moisture contents. It is concluded that when the vapor pressure is present, concrete will behave much more brittlely.

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Erzar, B., and E. Buzaud. "Shockless spalling damage of alumina ceramic." European Physical Journal Special Topics 206, no. 1 (May 2012): 71–77. http://dx.doi.org/10.1140/epjst/e2012-01588-0.

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Ozawa, Mitsuo, Zhou Bo, Yuichi Uchida, and Hiroaki Morimoto. "Preventive Effects of Fibers on Spalling of UFC at High Temperatures." Journal of Structural Fire Engineering 5, no. 3 (August 19, 2014): 229–38. http://dx.doi.org/10.1260/2040-2317.5.3.229.

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This paper investigates the relationship between spalling behavior and weight loss for ultra-high-strength fiber-reinforced concrete (UFC) containing different types short fibers (jute, PP, WSPVA) in high-temperature environments at 400, 600 and 800 °C. The explosive spalling that occurred under these conditions caused severe damage to the control specimen but only slight damage to the specimen with jute fiber. It was therefore inferred that adding 0.19% by volume of natural jute fibers (length: 12 mm) to UFC is effective in the prevention of spalling-related damage.

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Potisuk, Tanarat, Christopher C. Higgins, Thomas H. Miller, and Solomon C. Yim. "Finite Element Analysis of Reinforced Concrete Beams with Corrosion Subjected to Shear." Advances in Civil Engineering 2011 (2011): 1–14. http://dx.doi.org/10.1155/2011/706803.

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Finite element (FE) modeling techniques were developed to isolate the different contributions of corrosion damage to structural response of experimental reinforced concrete beams with shear-dominated behavior. Corrosion-damage parameters included concrete cover spalling due to the expansion of corrosion products; uniform stirrup cross-sectional loss from corrosion; localized stirrup cross-sectional loss due to pitting; debonding of corrosion-damaged stirrups from the concrete. FE analyses were performed including both individual and combined damages. The FE results matched experimental results well and quantitatively estimated capacity reduction of the experimental specimens.

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Diederichs, Mark S. "The 2003 Canadian Geotechnical Colloquium: Mechanistic interpretation and practical application of damage and spalling prediction criteria for deep tunnelling." Canadian Geotechnical Journal 44, no. 9 (September 2007): 1082–116. http://dx.doi.org/10.1139/t07-033.

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Spalling and strain bursting has long been recognized as a mechanism of failure in deep underground mines in hard rock and in deep infrastructure tunnels. The latter is a significant growth industry, particularly in Europe where subalpine base tunnels in excess of 10 m wide and dozens of kilometres long are being driven by tunnel boring machine (TBM) through alpine terrain at depths greater than 2 km. In more massive granitoid or gneissic ground, these tunnels have experienced significant spalling damage. En route to a practical predictive technique for this condition, the author utilizes a number of analytical and micromechanical tools to validate a simple empirical predictive model for tunnel spall initiation. The true nature of damage and of yield, as the result of extensile damage accumulation, in hard rocks is examined using these tools. Based on the resultant conceptual model, the author expands on the empirical damage threshold, using a spalling limit to differentiate stress paths that lead to crack propagation and spalling from those that incur stable microdamage prior to conventional shear failure at higher relative confinements. Finally, the composite and robust in situ yield model is applied to nonlinear modelling for support design.

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Eratodi, I. Gusti Lanang Bagus, Ali Awaludin, Ay Lie Han, and Andreas Triwiyono. "Evaluation and Study of Prestressed Slab Structure Precast Modular Concrete." MEDIA KOMUNIKASI TEKNIK SIPIL 26, no. 1 (July 30, 2020): 44–51. http://dx.doi.org/10.14710/mkts.v26i1.27765.

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Prestressed precast modular concrete slabs function rigid pavement, supporting vehicle loads above it on subgrade with relatively low bearing capacity. This slab measures 2000 x 850 x 150 mm3 of regular reinforced concrete (old production) or prestressed concrete (new production) quality K-500. After several times of use, damage occurs mainly at the end of the slab in the form of spalling. The objectives of the study and evaluation were: (1) observing damage; (2) material quality data; (3) numerical modeling by taking into account material properties, loading and soil conditions; and (4) providing slab design recommendations including materials and geometrics. The method of study and evaluation of slab damage was done by observing the damage, taking concrete core-case and testing it in the laboratory, and modeling the slab structure with various parameters (soil data, concrete quality and slab geometry). Field observations and analysis results show that concrete slab spalling occurs initially at the edge (850 mm wide) which in turn causes the effectiveness of the pre-tension force to be suboptimal and finally the concrete spalling volume increases. Apart from the frequency of collisions during installation and slab deformation when supporting vehicle loads. Concrete spalling problems also due to inappropriate concrete quality.

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Chu, Hong Yan, Jin Yang Jiang, Wei Sun, and Ming Zhong Zhang. "Mechanical Properties and Damage Evolution of Siliceous Concrete Subjected to Elevated Temperatures." Key Engineering Materials 711 (September 2016): 488–95. http://dx.doi.org/10.4028/www.scientific.net/kem.711.488.

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Siliceous concrete (SC) is applied in European Pressurized Water Reactor that is a key component of the third generation nuclear power plant. This paper investigates the mechanical properties and damage evolution of SC (with and without polypropylene fibers) exposed to high temperatures. The mass loss, compressive strength, splitting tensile strength and spalling sensitivity of SC before and after being heated to 200, 400, 600, 800, and 1000 °C are investigated. The ultrasonic testing technique was used to assess the thermal damage, by evaluating the variations of the ultrasonic wave velocity (UWV) for different temperature levels. According to the available literature, a new relationship between damage and UWV was proposed to establish a damage evolution model of SC. The results indicated that: (a) specimens without polypropylene (PP) fibers suffered severe spalling in the range 380-400°C and 470-510°C, while no spalling took place in the specimens with PP fibers in the whole range 25-1000°C; (b) the damage evolution with and without polypropylene fibers was similar, and could adequately be described by means of a Weibull distribution model.

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Celeste Blasone, Maria, Dominique Saletti, Edward Andò, Julien Baroth, and Pascal Forquin. "Investigation of Spalling Damage in Ultra-High Performance Concrete Through X-ray Computed Tomography." EPJ Web of Conferences 183 (2018): 03024. http://dx.doi.org/10.1051/epjconf/201818303024.

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Ultra-high performance concretes (UHPC) are increasingly used to build protective structures such as headquarters, nuclear power plants or critical civil engineering structures. However, under impact or contact detonation, concrete is exposed to high-rate tensile loadings that can lead to intense damage modes. Such complex damage modes need to be correctly characterised. When a UHPC sample is subjected to a dynamic tensile loading by means of the spalling technique the post-mortem pattern shows a large number of fractures that cannot be seen with a classical observation of the external face (inner crack network). In the framework of the Brittle’s CODEX chair project, the fracturing process in spalled samples of UHPC is investigated with X-ray computed tomography. The tensile loading is applied thanks to a spalling technique that is based on the reflection of a compressive wave on a free boundary. The concrete samples are entirely scanned using X-ray tomography prior spalling test to identify the initial microstructure, and post spalling test to analyse the damage pattern. Image analysis tools are used in both steps. The main fracturing properties are related to the microstructure of the tested concrete.

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Wang, Shimin, Chuankun Liu, Gaoyu Ma, Songyu Cao, Junbo Zhang, Daiyue Lu, and Chuan He. "Experimental Investigation on the Influence of Regional Concrete Spalling on Shield Tunnel Segments." Advances in Civil Engineering 2019 (June 27, 2019): 1–15. http://dx.doi.org/10.1155/2019/1829124.

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Based on the field investigation and analysis, the mechanical characteristics of segment structure in shield tunnels are compared and analyzed under the circumstances of different concrete spalling region by the method of similarity model experiment. Through data analysis of acoustic emission, the results for displacement and internal force of shield tunnel segments are clarified on the segment lining, the influential rule of load bearing capacity is also determined, and the deformation and stress for the different concrete spalling region are described as well. The corresponding research results indicate that range for elastic bearing stage is enlarged while it is narrowed for plastic bearing stage, the convergence and deformation and the accumulated event numbers for acoustic emission on critical instability point are obviously increasing, and the process of damage and failure tends to be sudden for segment lining structure. The ultimate bearing capacity of the damaged segment lining obviously decreases due to regional concrete spalling; to be more specific, the reduction rate for ultimate bearing capacity becomes 6%, 6%, and 13%, respectively, when the range of concrete spalling reaches 45°, 60°, and 75°.

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Park, Gang-Kyu, Gi-Joon Park, Jung-Jun Park, Namkon Lee, and Sung-Wook Kim. "Residual Tensile Properties and Explosive Spalling of High-Performance Fiber-Reinforced Cementitious Composites Exposed to Thermal Damage." Materials 14, no. 7 (March 25, 2021): 1608. http://dx.doi.org/10.3390/ma14071608.

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This study examined the effect of adding synthetic fibers, that is, polypropylene (PP) and nylon (Ny), on explosive spalling and residual tensile mechanical properties of high-performance fiber-reinforced cementitious composites (HPFRCCs). Three different matrix strengths (100 MPa, 140 MPa, and 180 MPa), four different volume contents of the synthetic fibers (0%, 0.2%, 0.4%, and 0.6%), and three different exposure time (1 h, 2 h, and 3 h) based on the Internatinoal Organization for Standardization (ISO) fire curve were adopted as variables for this experiment. The experimental results revealed that the addition of synthetic fibers improved the resistance to explosive spalling induced by high-temperature, especially when PP and Ny were mixed together. For a higher matrix strength, greater volume content of the synthetic fibers was required to prevent explosive spalling, and higher residual strengths were obtained after the fire tests. An increase in the volume fraction of the synthetic fibers clearly prevented explosive spalling but did not affect the residual tensile strength. In the case of a higher matrix strength, a reduction in the strength ratio was observed with increased exposure time.

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Hajihasani, Nadia, and Norhisham Bakhary. "Detection of Concrete Spalling Using Changes in Modal Flexibility." Advanced Materials Research 163-167 (December 2010): 2598–602. http://dx.doi.org/10.4028/www.scientific.net/amr.163-167.2598.

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This paper presents a study in the effect of spalling to dynamic parameters such as natural frequencies and mode shapes. Numerical example of a slab is used as an example in this study. The slab will be modelled using ANSYS 11.0 and various types of spalling are imposed. The changes of vibration parameters are monitored and compared. To compare the sensitivity of modal parameters to spalling is determined using the flexibility method. Based on the results it is found that by incorporating mode shapes using flexibility method, damage location and severity can be obtained.

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Aptukov, V. N. "Model of thermoviscoelastoplastic material damage. Application to spalling failure." Combustion, Explosion, and Shock Waves 22, no. 2 (1986): 244–53. http://dx.doi.org/10.1007/bf00749274.

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13

Yoo, S. H., S. W. Shin, and I. K. Kim. "Optimum Dosage of PP Fiber for the Spalling Control of High Strength Reinforced Concrete Columns." Key Engineering Materials 348-349 (September 2007): 621–24. http://dx.doi.org/10.4028/www.scientific.net/kem.348-349.621.

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Spalling is defined as damages to concrete exposed to high temperature during fire, causing cracks and localized bursting of small pieces of concrete. As the concrete strength increases, the degree of damage caused by spalling becomes more serious due to impaired permeability. It has been reported that polypropylene(PP) fiber has an important role in protecting concrete from spalling, and the optimum dosage of PP fiber is 0.2%. However, this result was based on the fire test of non-reinforced concrete specimens. The high-temperature behavior of highstrength reinforced concrete columns with various concrete strength and various quantity of PP fibers is investigated in this study. The results revealed that the ratio of unstressed residual strength of columns increased as the concrete strength increased and as the quantity of PP fiber increased from 0% to 0.2% the residual strength of columns increase. However, the effect of PP fiber quantity on residual strength of column was barely above 0.2%.

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Yin, Guo Xiang, Yong Li, Jun Hong Chen, and Xin Kui Gao. "The Wear Mechanism Comparison between MgO-Based Chrome-Free Brick and MgO-Cr₂O₃ Brick in the Lower Part of RH Vacuum Degasser." Advanced Materials Research 476-478 (February 2012): 1991–96. http://dx.doi.org/10.4028/www.scientific.net/amr.476-478.1991.

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The damage and improvement mechanism of rebonded MgO-Cr2O3 brick and MgO-ZrO2 brick used in the lower part of RH vacuum degasser were studied. The results show that the main damage of rebonded MgO-Cr2O3 brick is structure spalling because of the penetration of slag. MgO-ZrO2 brick has characteristics of high direct-bonding degree, small air permeability and making the viscosity of penetrated slag increased by means of ZrO2 absorbing CaO in slag to form CaZrO3 or ZrO2 solid solution, which make the degree of slag penetration decrease and improve the structure spalling resistance. MgO-ZrO2 brick has the defect of poor thermal shock resistance in use, the incorporation of MgO-rich spinel into MgO-ZrO2 brick significantly improved both thermal shock resistance and hot modulus of rupture because of the formation of eutectoid structure of grain-refining spinel and zirconia, which also improved structure spalling resistance because air permeability was decreased to 5% of MgO-ZrO2 brick

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Zhu, Hehua, Xiangyang Wei, J. Woody Ju, Qing Chen, Zhiguo Yan, and Yi Shen. "Statistical micromechanical damage model for SH-SFRC under tensile load considering the interfacial slip-softening and matrix spalling effects." International Journal of Damage Mechanics 30, no. 9 (April 20, 2021): 1423–49. http://dx.doi.org/10.1177/10567895211011225.

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Strain hardening behavior can be observed in steel fiber reinforced concretes under tensile loads. In this paper, a statistical micromechanical damage framework is presented for the strain hardening steel fiber reinforced concrete (SH-SFRC) considering the interfacial slip-softening and matrix spalling effects. With a linear slip-softening interface law, an analytical model is developed for the single steel fiber pullout behavior. The crack bridging effects are reached by averaging the contribution of the fibers with different inclined angles. Afterwards, the traditional snubbing factor is modified by considering the fiber snubbing and the matrix spalling effects. By adopting the Weibull distribution, a statistical micromechanical damage model is established with the fracture mechanics based cracking criteria and the stress transfer distance. The comparison with the experimental results demonstrates that the proposed framework is capable of reproducing the SH-SFRC’s uniaxial tensile behavior well. Moreover, the impact of the interfacial slip-softening and matrix spalling effects are further discussed with the presented framework.

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Hossain, Muhammad Monowar, Safat Al-Deen, Md Kamrul Hassan, Sukanta Kumer Shill, Md Abdul Kader, and Wayne Hutchison. "Mechanical and Thermal Properties of Hybrid Fibre-Reinforced Concrete Exposed to Recurrent High Temperature and Aviation Oil." Materials 14, no. 11 (May 21, 2021): 2725. http://dx.doi.org/10.3390/ma14112725.

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Over the years, leaked fluids from aircraft have caused severe deterioration of airfield pavement. The combined effect of hot exhaust from the auxiliary power unit of military aircraft and spilt aviation oils have caused rapid pavement spalling. If the disintegrated concreted pieces caused by spalling are sucked into the jet engine, they may cause catastrophic damage to the aircraft engine or physical injury to maintenance crews. This study investigates the effectiveness of incorporating hybrid fibres into ordinary concrete to improve the residual mechanical and thermal properties to prevent spalling damage of pavement. Three fibre-reinforced concrete samples were made with micro steel fibre and polyvinyl alcohol fibre with a fibre content of zero, 0.3%, 0.5% and 0.7% by volume fraction. These samples were exposed to recurring high temperatures and aviation oils. Tests were conducted to measure the effects of repeated exposure on the concrete’s mechanical, thermal and chemical characteristics. The results showed that polyvinyl alcohol fibre-, steel fibre- and hybrid fibre-reinforced concrete suffered a 52%, 40% and 26.23% of loss of initial the compressive strength after 60 cycles of exposure to the conditions. Moreover, due to the hybridisation of concrete, flexural strength and thermal conductivity was increased by 47% and 22%. Thus, hybrid fibre-reinforced concrete performed better in retaining higher residual properties and exhibited no spalling of concrete.

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Wen, Quan, Hang Gao, D. Zhao, and Dong Ming Guo. "Drilling C/E Composites with Electroplated Diamond Abrasive Tool and its Damage Evaluation Method." Key Engineering Materials 487 (July 2011): 371–75. http://dx.doi.org/10.4028/www.scientific.net/kem.487.371.

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Carbon/epoxy (C/E) composites have been widely used in aerospace and automotive industry. However, they are prone to appear damages such as burr, spalling, delamination during drilling process. This paper presents an electroplated diamond abrasive drilling (EDAD) technology to reduce these damages. With this technology, C/E composites are removed by the action of the motion of small diamond particles attached to a core drill body. In order to represent the drilling damages, a new evaluation method is proposed taking comprehensive consideration of burr, spalling and delamination. The method is verified by analyzing the damages of drilled holes. Results indicate that the evaluation method proposed in this paper is applicable to characterize the level of drilling damages reasonably and effectively.

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Wang, Ligang, and Dan G. Zollinger. "Mechanistic Design Framework for Spalling Distress." Transportation Research Record: Journal of the Transportation Research Board 1730, no. 1 (January 2000): 18–24. http://dx.doi.org/10.3141/1730-03.

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Spalling is a distress form in concrete pavements that often manifests as the breakdown of the joint of a slab within 15 cm (6 in.) of the joint or crack and can occur at both longitudinal and transverse joints. Efforts have been under way at Texas A&M University to formulate mechanistic spalling models derived from data gathered in recent Texas Department of Transportation studies related to spall development. Extensive field studies have led to the establishment of a spalling mechanism consisting of a step-by-step process that can be characterized with engineering mechanics. These findings indicate that spalling is the result of damage initiated in the form of a shear delamination that is oriented parallel to and at a shallow depth below the surface of the pavement. Conditions necessary for formation of the delaminations include low interfacial strength between the aggregate and mortar and sufficient evaporation of pore water from the hydrating concrete, resulting in differential drying shrinkage near the pavement surface. Delaminations have been noted to initiate early in the life of the pavement and, once formed, extend later into spalls as a result of incompressibles, freeze-thaw cycles, traffic loading, and other such effects. A design framework for delamination formation and subsequent spalling development is presented in a practical format in which to mechanistically design concrete pavement systems relative to spalling distress.

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Pagni, Catherine A., and Laura N. Lowes. "Fragility Functions for Older Reinforced Concrete Beam-Column Joints." Earthquake Spectra 22, no. 1 (February 2006): 215–38. http://dx.doi.org/10.1193/1.2163365.

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Fragility functions are developed to predict the method of repair required for older reinforced concrete beam-column joints damaged due to earthquake loading. The results of previous experimental studies are used to develop empirical relationships between damage states and engineering demand parameters, such as interstory drift, joint deformation, and number of load cycles. Damage states are proposed and linked deterministically with commonly employed methods of repair; these damage states are characterized by parameters such as concrete crack width, extent of concrete spalling, and yielding and buckling of reinforcement. Probability distributions are fit to the empirical data and evaluated using standard statistical methods. The results of this effort are families of fragility functions that predict the required method of repair for a damaged joint.

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Lu, Shuaifeng, Sifei Liu, Zhijun Wan, Jingyi Cheng, Zhuangzhuang Yang, and Peng Shi. "Dynamic Damage Mechanism of Coal Wall in Deep Longwall Face." Advances in Civil Engineering 2019 (December 14, 2019): 1–10. http://dx.doi.org/10.1155/2019/3105017.

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The stability of coal wall in deep longwall face has always been a research hotspot. In this study, pure vibration signals in the coal wall during the operation of mining machinery were obtained for the first time, and their energy is mainly concentrated in 7–12 Hz. Besides, based on the law of stress wave propagation, with the coal wall of deep longwall taken as the research object, the theory of dynamic damage in coal wall was put forward from the perspective of dynamics. The results show that the loading and unloading waves generated by the mining machinery disturbance will be reflected and transmitted at the interface with different impedances, resulting in the formation of multiple unloading and loading waves and multiple tensile stress zones and stress concentration zones. These stress concentration zones tend to induce tensile stress generation and coal failure. As a result, the coal undergoes zonal failure and spalling. Through the vibration test of coal, it is found that the crack development of the coal sample can be divided into five stages, and the phenomena of zonal failure and spalling occur, which is consistent with the theory. At the same time, the sample that has gone through a large disturbance cannot be further damaged by a small disturbance, which is verified by the damage statistical constitutive model based on the isotropy hypothesis.

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Li, Guosheng, Zhenhua Li, Feng Du, and Zhengzheng Cao. "Study on the Failure Characteristics of Coal Wall Spalling in Thick Coal Seam with Gangue." Advances in Civil Engineering 2020 (December 14, 2020): 1–10. http://dx.doi.org/10.1155/2020/6668458.

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Coal wall spalling is one of the main factors restricting the safe and efficient mining of thick coal seam, and the gangue has an important impact on the coal wall spalling. To obtain the failure characteristics of coal wall spalling in thick coal seam containing gangue, numerical calculation and theoretical research were used to analyze the morphological differences of coal wall spalling with different gangue positions. Besides, the damage depth, width, and stress environment of coal wall panel caused by the position of gangue were mainly studied, and the failure mechanics model of coal seam containing gangue was established by using the stability theory of pressure bar. The results show that, compared with coal wall spalling in coal seam without gangue, coal seam with the lower and middle gangue has a significant weakening effect on the wall spalling, and coal seam with the upper gangue has little effect on the wall spalling. In the case of coal seam with gangue, the upper gangue has the highest risk area of coal wall spalling with the maximum depth and width of 2.0 m and 2.3 m. For coal seam with the upper gangue, the dangerous areas of coal wall spalling are mainly distributed in the vicinity of the gangue; for coal seam without the gangue, they are mainly distributed in the middle of the coal seam. The gangue cannot change the law of the external stress distribution of the coal seam, but it has an obvious impact on the internal stress distribution of the coal seam. With the different positions of the gangue, the stress distribution in the coal seam has a great difference, and the maximum difference is 1.8 MPa. This shows that the stress environment of the coal seam containing gangue has the following typical characteristics: “the external stress is controlled by the overburden fracture, and the internal stress environment is controlled by the gangue.” Through the mechanical analysis of the coal seam containing gangue, it is further verified that the coal seam containing gangue is more prone to spalling at the position of gangue.

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Llorca, F., G. Roy, and P. Antoine. "Ductile damage of tantalum under spalling effects. Experimental and metallurgical analysis." Le Journal de Physique IV 10, PR9 (September 2000): Pr9–775—Pr9–780. http://dx.doi.org/10.1051/jp4:20009128.

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Saadati, Mahdi, Pascal Forquin, Kenneth Weddfelt, and Per-Lennart Larsson. "On the Tensile Strength of Granite at High Strain Rates considering the Influence from Preexisting Cracks." Advances in Materials Science and Engineering 2016 (2016): 1–9. http://dx.doi.org/10.1155/2016/6279571.

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The dynamic tensile behavior of granite samples, when some preexisting cracks are introduced artificially, is investigated. Spalling tests using a Hopkinson bar are performed and strain rates of ~102 1/s are obtained in both specimen types (with and without initial cracks). This experimental technique is employed being of the same order as strain rates in rock materials during percussive drilling, the application of interest here. The dynamic tensile responses of both sample-sets are compared using the velocity profile measured on the free-end of the sample. Furthermore, an anisotropic damage model based on the concept of obscuration probability describes the response without preexisting cracks. Here, a term of cohesive strength in obscuration zones is added to accurately handle the softening behavior of the material in tension. Results from the spalling tests are used to validate the model prediction of the dynamic tensile strength and also to calibrate the cohesive model parameters. Damaged elements are numerically introduced in the finite element calculations simulating the spalling experiments performed on predamaged samples. The results are compared with the experimental ones. Good agreement is obtained showing that a two-scale approach may constitute a suitable method to simulate numerically the tensile response of predamaged granite.

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Zuo, Yu Jun, Chun An Tang, Wan Cheng Zhu, and Lian Chong Li. "Influence of Duration of Stress Wave on the Spallation Process in Inhomogeneous Material." Key Engineering Materials 353-358 (September 2007): 917–20. http://dx.doi.org/10.4028/www.scientific.net/kem.353-358.917.

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Based on mesoscopic damage mechanics, a numerical code RFPA2D (dynamic version) is developed to simulate the spallation process of inhomogeneous medium induced by reflection of stress wave, and the influence of duration of stress wave on spallation is discussed. For convenience of description and discussion, the failure area in the immediate vicinity of loading position of model is divided into two zones, i.e. comminution zone and fracture zone; and the failure area caused by spalling in model is defined as spalling zone. The comminution zone is affected little by the duration of stress wave, but the fracture zone and the spalling zone are affected to a greater extent by duration, also, the stability of specimen is affected by the duration of stress wave. Furthermore, if the duration becomes significantly long, the fracture zone corresponding to the maximum extension of the radial tensile cracks will be dominant in specimen. If the duration of stress wave becomes short to some extent, the spalling zone corresponding to the maximum extension of the tangential tensile cracks will be dominant in specimen. In addition, if the duration of stress wave is long enough, the specimen may lose stability.

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Guo, Liping, Wenxiao Zhang, Wei Sun, Bo Chen, and Yafan Liu. "High-Temperature Performance and Multiscale Damage Mechanisms of Hollow Cellulose Fiber-Reinforced Concrete." Advances in Materials Science and Engineering 2016 (2016): 1–14. http://dx.doi.org/10.1155/2016/2503780.

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Spalling resistance properties and their damage mechanisms under high temperatures are studied in hollow cellulose fiber-reinforced concrete (CFRC) used in tunnel structures. Measurements of mass loss, relative dynamic elastic modulus, compressive strength, and splitting tensile strength of CFRC held under high temperatures (300, 600, 800, and 1050°C) for periods of 2.5, 4, and 5.5 h were carried out. The damage mechanism was analyzed using scanning electron microscopy, mercury intrusion porosimetry, thermal analysis, and X-ray diffraction phase analysis. The results demonstrate that cellulose fiber can reduce the performance loss of concrete at high temperatures; the effect of holding time on the performance is more noticeable below 600°C. After exposure to high temperatures, the performance of ordinary concrete deteriorates faster and spalls at 700–800°C; in contrast, cellulose fiber melts at a higher temperature, leaving a series of channels in the matrix that facilitate the release of the steam pressure inside the CFRC. Hollow cellulose fibers can thereby slow the damage caused by internal stress and improve the spalling resistance of concrete under high temperatures.

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Shi, Luojie, Juan Wen, Baisong Pan, Yongyong Xiang, Qi Zhang, and Congkai Lin. "Dynamic Characteristics of a Gear System with Double-Teeth Spalling Fault and Its Fault Feature Analysis." Applied Sciences 10, no. 20 (October 11, 2020): 7058. http://dx.doi.org/10.3390/app10207058.

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Tooth spalling is one of the most destructive surface failure models of the gear faults. Previous studies have mainly concentrated on the spalling damage of a single gear tooth, but the spalling distributed over double teeth, which usually occurs in practical engineering problems, is rarely reported. To remedy this deficiency, this paper constructs a new dynamical model of a gear system with double-teeth spalling fault and validates this model with various experimental tests. The dynamic characteristics of gear systems are obtained by considering the excitations induced by the number of spalling teeth, and the relative position of two faulty teeth. Moreover, to ensure the accuracy of dynamic model verification results and reduce the difficulty of fault feature analysis, a novel parameter-adaptive variational mode decomposition (VMD) method based on the ant lion optimization (ALO) is proposed to eliminate the background noise from the experimental signal. First, the ALO is used for the self-selection of the decomposition number K and the penalty factor â of the VMD. Then, the raw signal is decomposed into a set of Intrinsic Mode Functions (IMFs) by applying the ALO-VMD, and the IMFs whose effective weight kurtosis (EWK) is greater than zero are selected as the reconstructed signal. Combined with envelope spectrum analysis, the de-nosing ability of the proposed method is compared with that of the method known as particle swarm optimization-based variational mode decomposition (PSO-VMD), the fixed-parameter VMD, the empirical mode decomposition (EMD), and the local mean decomposition (LMD), respectively. The results indicate that the proposed dynamic model and background elimination method can provide a theoretical basis for spalling defect diagnosis of gear systems.

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Duarte, D., F. Nex, N. Kerle, and G. Vosselman. "DAMAGE DETECTION ON BUILDING FAÇADES USING MULTI-TEMPORAL AERIAL OBLIQUE IMAGERY." ISPRS Annals of Photogrammetry, Remote Sensing and Spatial Information Sciences IV-2/W5 (May 29, 2019): 29–36. http://dx.doi.org/10.5194/isprs-annals-iv-2-w5-29-2019.

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Abstract. Over the past decades, a special interest has been given to remote-sensing imagery to automate the detection of damaged buildings. Given the large areas it may cover and the possibility of automation of the damage detection process, when comparing with lengthy and costly ground observations. Currently, most image-based damage detection approaches rely on Convolutional Neural Networks (CNN). These are used to determine if a given image patch shows damage or not in a binary classification approach. However, such approaches are often trained using image samples containing only debris and rubble piles. Since such approaches often aim at detecting partial or totally collapsed buildings from remote-sensing imagery. Hence, such approaches might not be applicable when the aim is to detect façade damages. This is due to the fact that façade damages also include spalling, cracks and other small signs of damage. Only a few studies focus their damage analysis on the façade and a multi-temporal approach is still missing. In this paper, a multi-temporal approach specifically designed for the image classification of façade damages is presented. To this end, three multi-temporal approaches are compared with two mono-temporal approaches. Regarding the multi-temporal approaches the objective is to understand the optimal fusion between the two imagery epochs within a CNN. The results show that the multi-temporal approaches outperform the mono-temporal ones by up to 22% in accuracy.

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Zhao, Jie, Jian Jun Zheng, Gai Fei Peng, and Klaas van Breugel. "Mesoscopic Thermal-Mechanical Fire Damage Modeling of High Performance Concrete." Advanced Materials Research 194-196 (February 2011): 1095–98. http://dx.doi.org/10.4028/www.scientific.net/amr.194-196.1095.

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High performance concrete will undergo thermal-mechanical degradation or even spalling under high temperature conditions, such as fire, and the safety of concrete structures will be endangered. To prevent concrete from fire damage, the damage mechanism should be thoroughly understood. In this paper, an anisotropic damage model is presented to analyze the thermal-mechanical degradation of concrete. The vapor pressure and the moisture transport are taken into account. The damage evolution history can be traced with the temperature propagation and the degree of material degradation can be predicted through the model.

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Wang, Kaikai, Zhunli Tan, Cheng Cheng, Bo Gao, Guhui Gao, R. D. K. Misra, and Bingzhe Bai. "Effect of microstructure on the spalling damage in a 20Mn2SiCrMo bainitic rail." Engineering Failure Analysis 70 (December 2016): 343–50. http://dx.doi.org/10.1016/j.engfailanal.2016.09.011.

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Liu, Hui Min. "Numerical Simulation of Thermal Shock Tests of Carbon-Containing Refractories." Advanced Materials Research 538-541 (June 2012): 660–64. http://dx.doi.org/10.4028/www.scientific.net/amr.538-541.660.

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To appraise the thermal shock resistance of carbon-containing refractories correctly, its thermal stress changes in thermal shock tests were analyzed by finite element method, and the mathematical model appraising its thermal shock fracture was built. The results show when the sample of carbon-containing refractory suffers thermal shock, the main damaged areas lie its centre during sharp heating process, but the sides during quenching process. The later is the main reason causing its damage. When appraising the thermal shock resistance of carbon-containing refractory by dip spalling method, the result matches fracture index.

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Keller, Wesley J., and Stephen Pessiki. "Effect of Earthquake-Induced Damage on the Sidesway Response of Steel Moment-Frame Buildings during Fire Exposure." Earthquake Spectra 31, no. 1 (February 2015): 273–92. http://dx.doi.org/10.1193/123112eqs362m.

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Spray-applied fire-resistive material (SFRM) is prone to debonding, cracking, and spalling in steel moment-frame plastic hinge regions during inelastic seismic response. To evaluate the effect of experimentally observed earthquake-induced SFRM spall patterns on building sidesway response during an ensuing fire, an analytical case study is developed for a steel special moment-frame building with a seismic hazard representative of coastal California. Response data from numerical earthquake simulations indicate that damage to SFRM insulation in beam hinge regions should be anticipated following ground shaking representative of the maximum considered seismic hazard. Thermomechanical post-earthquake fire simulations demonstrate that earthquake-induced SFRM spalling significantly increases thermal degradation in the affected beam hinge regions during fire exposure, leading to pronounced softening of moment-rotation response for the beam-column assemblies. This temperature-induced moment-frame connection softening increases the flexibility of the structural system for sidesway motion and exacerbates drift demands under the action of residual destabilizing forces.

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Kwon, Seok Jin, Dong Hyung Lee, Jung Won Seo, and Hyun Mu Hur. "Mechanical Properties of Railway Wheel for Standard Reinforcement." Advanced Materials Research 26-28 (October 2007): 1247–50. http://dx.doi.org/10.4028/www.scientific.net/amr.26-28.1247.

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For the high quality of wheel, the railway wheel has standardized such as UIC, KS, and JIS code but the chemical composition, the mechanical property and the hardness is merely requested. Although the standard of railway wheel has sustained, the damages of railway wheel have been occurred in service running. Because of wheel damage with spalling, shelling and thermal crack, the maintenance cost for the railway wheel has increased. In order to reduce wheel damage, it is necessary to reinforce the standard of railway wheel. In present study, the fracture mechanics characteristics of railway wheel such as threshold stress intensive factor, fracture toughness and impact energy depended on temperature have tested. The result shows that the standard of railway wheel has to supplement fracture toughness and impact energy depended on low temperature in order to reduce the wheel damage.

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Hvizdoš, Pavol, Ravikiran Chintapalli, Jorge Valle, and Marc Anglada. "Effect of Low Temperature Degradation on Scratch Behaviour of 3Y-TZP." Key Engineering Materials 409 (March 2009): 322–25. http://dx.doi.org/10.4028/www.scientific.net/kem.409.322.

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Effect of low-temperature degradation of 3Y-TZP ceramics (polycrystalline zirconia stabilized by 3mol% of yttria) on contact damage resistance has been studied applying scratch testing technique. Friction properties and damage mechanisms have been investigated for various degrees of hydrothermal ageing, i.e. for different grain sizes and crystallography, and for different thickness of the degraded surface layer. The onset of plastic damage, catastrophically cracking, grain pull-out, spalling and chipping due to top layer debonding have been identified. The contact damage micromechanisms corresponding to various degrees of degradation have been studied in detail by interferometry and microscopy.

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Olsen, Michael J., Kwok Fai Cheung, Yoshiki YamazakI, Shawn Butcher, Maria Garlock, Solomon Yim, Sara McGarity, Ian Robertson, Luis Burgos, and Yin Lu Young. "Damage Assessment of the 2010 Chile Earthquake and Tsunami Using Terrestrial Laser Scanning." Earthquake Spectra 28, no. 1_suppl1 (June 2012): 179–97. http://dx.doi.org/10.1193/1.4000021.

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In the wake of the 2010 Chile earthquake and tsunami, a reconnaissance survey recorded earthquake and tsunami damage using terrestrial laser scanning (TLS), which is capable of detecting details that most traditional reconnaissance methods cannot. TLS enables precise measurements of structural deformations and damage (including shear cracking of concrete walls, concrete spalling, and damage of rebars), as well as soil deformations and damage (including erosion, scour, liquefaction, lateral spread, slope failure, and ground displacement). Advanced measurements such as minute structural rotations, spatial distribution of cracks, volumetric and positional change calculations can also be obtained. Herein, we present various types of detailed measurements and analyses using TLS data obtained at several sites that were damaged by the earthquake and/or tsunami in Concepción, Constitución, Dichato, and Talcahuano. Moreover, this high-resolution data has enabled a unique avenue for virtual, post-visit analysis, providing additional insights that were not readily observable during the field visit.

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Di Schino, Andrea, and Paolo Di Nunzio. "METALLURGICAL ASPECTS RELATED TO CONTACT FATIGUE PHENOMENA IN STEELS FOR BACK-UP ROLLS." Acta Metallurgica Slovaca 23, no. 1 (March 28, 2017): 62. http://dx.doi.org/10.12776/ams.v23i1.852.

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The need of even longer rolling sessions is driving the improvement of back up rolls in terms of wear resistance. This is also aimed to reduce costs. In this paper the effect of steel chemical composition on contact fatigue phenomena, bringing to the macroscopic damage named spalling is reported. Results show that the removal by grinding operations of damaged portion of rolls surface should be not sufficient to restore the initial performances of material. Experimental tests showed that a portion of material below the damaged one keeps memory of the last fatigue cycle, and has to be removed.

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36

Uotinen, Lauri Kalle Tapio, and Topias Kalle Aleksi Siren. "Elastoplastic Modelling of an In Situ Concrete Spalling Experiment Using the Ottosen Failure Criterion." Journal of Engineering 2017 (2017): 1–16. http://dx.doi.org/10.1155/2017/4723017.

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An in situ concrete spalling experiment will be carried out in the ONKALO rock characterization facility. The purpose is to establish the failure strength of a thin concrete liner on prestressed rock surface, when the stress states in both rock and concrete are increased by heating. A cylindrical hole 1.5 m in diameter and 7.2 m in depth is reinforced with a 40 mm thin concrete liner from level −3 m down. Eight 6 m long 4 kW electrical heaters are installed around the hole 1 m away. The experiment setup is described and results from predictive numerical modelling are shown. Elastoplastic modelling using the Ottosen failure criterion predicts damage initiation on week 5 and the concrete ultimate strain limit of 0.0035 is exceeded on week 10. The support pressure generated by the liner is 3.2 MPa and the tangential stress of rock is reduced by −33%. In 2D fracture mechanical simulations, the support pressure is 3 MPa and small localized damage occurs after week 3 and damage process slowly continues during week 9 of the heating period. In conclusion, external heating is a potent way of inducing damage and thin concrete liner significantly reduces the amount of damage.

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Feng, Zhi Peng, Ming J. Zuo, Ru Jiang Hao, and Fu Lei Chu. "Application of Cyclic Correlation Analysis to Gear Damage Detection." Key Engineering Materials 413-414 (June 2009): 621–26. http://dx.doi.org/10.4028/www.scientific.net/kem.413-414.621.

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The cyclic autocorrelation function is used with regard to the cyclostationarity of gear vibrations in order to extract the modulation features of gearbox vibration signals, and to detect localized gear damage. The properties of the amplitude and frequency modulated signals in the cyclic frequency domain are summarized in order to investigate the differences between the modulation features of normal and faulty gearbox vibration signals. Gear tooth spalling is detected by the presence of many sidebands in a zero-lag time-slice of the cyclic autocorrelation function, thereby indicating an increase in the degree of modulation effect. The damage source is located by the spacing of the sidebands.

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Bradáčová, Isabela, and Petr Kučera. "Concrete Structures Restoration from the Fire Safety Point of View." Advanced Materials Research 688 (May 2013): 113–19. http://dx.doi.org/10.4028/www.scientific.net/amr.688.113.

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The need of concrete structures restoration in order to ensure their fire resistance can, in engineering practice, occur for reasons of damage to the structure by fire (spalling of concrete cover layer) or by the failure to cover the load-bearing structure during construction. The paper is devoted to the evaluation of the structure cover of the evaluated structure, the determination of temperature distribution in the structure with consideration to the choice of probable fire scenario, subsequent determination of critical temperature of the structure and the optimization of possible methods of the restoration of damaged or wrongly made constructions.

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Kwon, Seok Jin, Jung Won Seo, Hyun Mu Hur, and Sung Tae Kwon. "Characteristics of Wheel Tread for Property Improvement of Railway Wheel." Key Engineering Materials 326-328 (December 2006): 1075–78. http://dx.doi.org/10.4028/www.scientific.net/kem.326-328.1075.

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Despite of improvement of wheel material for railway vehicle, the damages of railway wheel have been occurred in service running. Because of wheel damage with spalling, shelling and thermal crack, the maintenance cost for the railway wheel has increased. The railway wheel had standardized but the chemical composition, the mechanical property and the hardness with respect to railway wheel is merely established. In order to reduce wheel damage, it is necessary to reinforce the standard of railway wheel. In present study, the fracture mechanics characteristics of railway wheel such as low cycle fatigue, fracture toughness, impact energy depended on low temperature and so on have tested. The result shows that the standard of railway wheel has to supplement fracture toughness and impact energy depended on low temperature etc.

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40

Lenkovskiy, Taras, Andriy Dzyubyk, Volodymyr Vira, Lyudmyla Dzyubyk, Volodymyr Topilnytskyy, Roman Kovalchuk, Zoia Duriagina, Volodymyr Volodymyrovych Kulyk, and Artem Glazov. "A new approach for evaluating the resistance of wheel steel to spall formation." Engineering review 40, no. 2 (April 1, 2020): 70–76. http://dx.doi.org/10.30765/er.40.2.08.

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An effective theoretical-experimental approach to evaluation of wheel steels resistance to contactfatigue damage (spalling) formation by pitting mechanism is proposed. On the base of the results of experimental studies and calculations, the contact-fatigue life curve of high-tempered 65Г steel is built. The results are similar and compared to a model low-tempered 75ХГСТ steel.

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41

Ma, Wei Hua, Shi Hui Luo, and Rong Rong Song. "Analysis of Wheel Set Longitudinal Vibration and the Correlated Dynamic Performance." Applied Mechanics and Materials 52-54 (March 2011): 1–6. http://dx.doi.org/10.4028/www.scientific.net/amm.52-54.1.

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Wheel set longitudinal vibration is a self-excited vibration when railway vehicle is running on the track, which is one of the important reasons of wheel tread spalling problem, and will cause the dynamic performance worse of the vehicle. To investigate the happen mechanism of the wheel set longitudinal vibration, the 7 degree of freedoms wheel set longitudinal vibration model which considers the torsion vibration of the wheel axle was set up based on Matlab. From the point of view of frequency and vibration, put forward one kind of forecast method of the happen of wheel set longitudinal vibration. Wheel set longitudinal vibration will lead car body to suffer an impact in the longitudinal direction and this would cause car body tremble and have a big vertical vibration. Take the locomotive which has severe wheel tread spalling problem running on the Kunming meter track for example to test the effect of the wheel set longitudinal vibration theory to solve the wheel tread spalling problem. Solve wheel tread damage from the aspect of dynamic is an evolution method and Wheel set longitudinal dynamic is the extension of the wheel/rail dynamic.

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42

Shi, Yanchao, Li Chen, Zhongqi Wang, and Xuejie Zhang. "Field Tests on Spalling Damage of Reinforced Concrete Slabs under Close-In Explosions." International Journal of Protective Structures 6, no. 2 (June 2015): 389–401. http://dx.doi.org/10.1260/2041-4196.6.2.389.

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Zinszner, Jean-Luc, Benjamin Erzar, and Pascal Forquin. "Strain rate sensitivity of the tensile strength of two silicon carbides: experimental evidence and micromechanical modelling." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 375, no. 2085 (January 28, 2017): 20160167. http://dx.doi.org/10.1098/rsta.2016.0167.

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Ceramic materials are commonly used to design multi-layer armour systems thanks to their favourable physical and mechanical properties. However, during an impact event, fragmentation of the ceramic plate inevitably occurs due to its inherent brittleness under tensile loading. Consequently, an accurate model of the fragmentation process is necessary in order to achieve an optimum design for a desired armour configuration. In this work, shockless spalling tests have been performed on two silicon carbide grades at strain rates ranging from 10 3 to 10 4 s −1 using a high-pulsed power generator. These spalling tests characterize the tensile strength strain rate sensitivity of each ceramic grade. The microstructural properties of the ceramics appear to play an important role on the strain rate sensitivity and on the dynamic tensile strength. Moreover, this experimental configuration allows for recovering damaged, but unbroken specimens, giving unique insight on the fragmentation process initiated in the ceramics. All the collected data have been compared with corresponding results of numerical simulations performed using the Denoual–Forquin–Hild anisotropic damage model. Good agreement is observed between numerical simulations and experimental data in terms of free surface velocity, size and location of the damaged zones along with crack density in these damaged zones. This article is part of the themed issue ‘Experimental testing and modelling of brittle materials at high strain rates’.

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44

Mark, William D. "Analytical approximations to damaged gear tooth transmission-error contributions for gear-health monitoring." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 230, no. 7-8 (September 29, 2015): 1157–82. http://dx.doi.org/10.1177/0954406215606930.

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A generic model of transmission-error contributions arising from gear-tooth damage is developed. Damage is modeled as material removed from tooth-working-surfaces. Regions of modeled tooth damage are of limited size as in pitting damage or are extended to full working surfaces as in tooth-bending-fatigue damage. Results are computed for a wide variety of damage forms and formulated for any collection of teeth experiencing damage. Final results are expressed as transmission-error rotational-harmonic amplitudes arising from damage. Rotational-harmonic regions experiencing significant damage contributions from pitting/spalling damage and from tooth-bending-fatigue damage are delineated. Increases in higher harmonic-number amplitudes arising from transmission-error discontinuities are formulated. The overall model framework can be used to explain and interpret observed features of gear transmission-error spectra arising from gear-tooth damage and to develop new methods of detecting and assessing the severity of such damage.

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Ren, Hua Chun, and Zhen Zhong Shen. "Analysis on Earthquake Damage Forms and Affecting Factors of Underground Cavern." Applied Mechanics and Materials 204-208 (October 2012): 2444–48. http://dx.doi.org/10.4028/www.scientific.net/amm.204-208.2444.

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According to the information about underground damage in earthquake all over the world, it is summarized that earthquake damage is caused by mountain slope failure, the collapse of cavern’s export, dislocation damage of cavern’s cross-section, great displacement along the fault intersection, spalling of surrounding rock, disturbance or deformation of the support and lining system, et. The earthquake damage factors of underground cavern were analyzed by using numerical simulation techniques. It is shown that when the earthquake intensity value is high, or the initial stress field is small, or lining stiffness is high, the underground will more easily be destroyed by earthquake. Compared with the square tunnel and horseshoe-shaped tunnel, dynamic stability of circular tunnel is better. The export of cavern is vulnerable to earthquake damage.

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46

Králik, Juraj. "Safety of Nuclear Power Plants against the Aircraft Attack." Applied Mechanics and Materials 617 (August 2014): 76–80. http://dx.doi.org/10.4028/www.scientific.net/amm.617.76.

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This paper presents the nonlinear dynamic analysis of the reinforced concrete building of nuclear power plant to the aircraft impact. The dynamic load is defined in time on the base of the simulation of the airplane impact considering real stiffness, masses, direction and velocity of the flight. The dynamic response is calculated in the system ANSYS using the transient nonlinear analysis solution method. The damage of the concrete wall is evaluated in accordance with the standard NDRC considering the spalling, scabbing and perforation effects. The simple and detailed calculations of the wall damage are compared.

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47

Li, Lian Chong, Chun An Tang, and P. A. Lindqvist. "Fracture Behavior in a Rock Pillar Subjected to Coupled Thermo-Mechanical Loading." Key Engineering Materials 324-325 (November 2006): 443–46. http://dx.doi.org/10.4028/www.scientific.net/kem.324-325.443.

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Using RFPA code, analyses have been carried out to investigate the stability of a rock pillar in a experiment for nuclear waste repositories, the numerically obtained stress field, temperature distribution, failure pattern of the pillar rock and associated AE events are all agree well with the in-situ data. Minor fracture initiation may take place in the vicinity of the boreholes after heating. Heating induces minor spalling at central pillar wall for 0.5 m sections below the tunnel floor, but the area of spalling is found to be limited. The core of the pillar remains intact for stress conditions corresponding to 120 days of heating which not only prove that the proposed technique provides a powerfully alternative and effective approach for the study on thermal-mechanical-damage coupling mechanism but also provide meaningful guides for the experiment design and associated applications.

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Zhu, Chuanqi, Shaobo Li, Yong Luo, and Biao Guo. "Progressive Damage Process and Failure Characteristics of Coal under Uniaxial Compression with Different Loading Rates." Shock and Vibration 2021 (September 4, 2021): 1–12. http://dx.doi.org/10.1155/2021/3360738.

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To study the effect of loading rate on the progressive damage and failure characteristics of coal, an ultrasonic detector and a camera were used to measure the P-wave velocity and record the failure process of cuboid coal samples in uniaxial compression tests with five loading rates. The mechanical properties, damage process, and failure characteristics of the samples were analysed, and the mechanism of the advancing velocity of the working face in coal failure was discussed. The results show that, as the loading rate increases, the peak strength of the sample generally shows an increasing trend, but the elastic modulus changes irregularly. The sample is more prone to local failure before the peak strength. An increase in the loading rate rapidly promotes damage in the sample and accelerates the transition from internal damage to macroscopic failure, with no obvious effect on the ratio of damage threshold to corresponding peak strength. At low loading rates, the samples mainly experienced static failure; the failure form was spalling, and the failure range was wide. At high loading rates, the samples were prone to dynamic failure in the local area, manifested as the ejection of slabs and debris. A greater loading rate produced smaller and thinner slabs and a greater ejection velocity. Properly increasing the advancing velocity of the working face is conducive to reducing spalling to prevent large-area roof fall, but it may increase the possibility of coal burst in local areas. The results of this study provide a reference for roof control and coal burst disaster prevention on the working face in deep coal mining.

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Kurt, Efe G., Barış Binici, Özgür Kurç, Erdem Canbay, Akpınar, and Güney Özcebe. "Seismic Performance of a Deficient Reinforced Concrete Test Frame with Infill Walls." Earthquake Spectra 27, no. 3 (August 2011): 817–34. http://dx.doi.org/10.1193/1.3609876.

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A two-story, three-bay RC frame with code incompliant seismic design and detailing is tested using continuous pseudodynamic test method for three scale levels of Düzce ground motion. The ground motion produced minimum, significant, and severe damage states on the test structure. Diagonal cracking of the infill wall, column damage in the form of cover spalling and rebar buckling, and complete disintegration of the infill wall were the important observed damage events for the three scale levels, respectively. Nonlinear time history analyses were able to estimate the story displacement response with reasonable accuracy. The importance of element removal for near collapse damage state is unfolded. Tracing the local engineering demand parameters such as strains and curvature was found to be extremely difficult.

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Prestes, E., A. S. A. Chinelatto, and W. S. Resende. "Post mortem analysis of burned magnesia-chromite brick used in short rotary furnace of secondary lead smelting." Cerâmica 55, no. 333 (March 2009): 61–66. http://dx.doi.org/10.1590/s0366-69132009000100008.

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Burned magnesia-chromite bricks are the standard product for the lining of furnaces in lead industry, where the short service life is a great problem. Used sintered magnesia-chromite brick sample from short rotary furnace lining, sent by a secondary lead manufacturer, showed parallel cracks to the hot face due to structural spalling damage. The refractory infiltrated region and slag interface were analyzed using a scanning electron microscope with an energy dispersive spectroscopy analyzer, and X-ray diffraction powder analysis. Crucible corrosion test was performed to evaluate the influence of slag attack. The results showed that the structural spalling was due to strong Pb-infiltration of the refractory microstructure by bath components of the furnace (metallic lead and lead sulphite) during the reduction process and that the slag infiltration had little contribution due to the good resistance of the magnesia-chromite bricks to FeO rich slag attack.

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Journal articles on the topic 'Spalling damage'

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