Tensile Stress Field Research Articles

In situ stress variation and coal reservoir permeability response of the Jurassic Yan'an formation in the southwestern Ordos basin, China: Its impact on coalbed methane development

The in situ stress (ISS) and permeability determine the coalbed methane (CBM) development method and extraction efficiency to a certain extent. Based on the data of the CBM well test and microseismic monitoring in the Jurassic Yan'an Formation, a prediction model of the ISS is established, and its influence on permeability and CBM development in the southwestern Ordos Basin, China, is discussed. The results show that the orientations of maximum principal stresses (Shmax) in the study area's eastern, central, and western parts are NE–SW, SEE–NWW, and NNW–SSE, respectively. With the increased burial depth, the main ISS parameters show an S-shaped variation. The study area's ISS state can be divided into Shmax > vertical stress (Sv) > horizontal minimum principal stress (Shmin) (<420 m), Sv > Shmax > Shmin (420 m–800 m), and Shmax ≈ Sv > Shmin (>800 m), and the transformation depth of the ISS field is 550 m and 1000 m. The lateral pressure coefficients (λ) ranged from 0.30 to 1.19, with an average of 0.69. The λ, Shmax/Shmin and Shmin/Sυ of the stress field are small, which indicates that the horizontal tectonic stress is weak. The coal reservoir's permeability is distributed between 0.0084 and 6.84 mD (av. 1.13 mD). Affected by the variation of the ISS state in the vertical direction, the coal reservoir permeability shows obvious zoning. The tensile stress field is beneficial to high-permeability coal reservoir formation, but it is constrained by the coupling constraints of a coal reservoir's confining pressure and effective stress. The coal reservoirs are in a normal fault stress state, which is beneficial for improving their hydraulic fracturing effect. Since the Shmin in the study area is always smaller than the Sυ, the height of the fracturing fracture should be controlled in the fracturing of the coal reservoir to avoid the overlying aquifer being connected by fracturing fractures. The above new insights have important guiding significance for the hyperpermeability CBM reservoir prediction, well-bore structure and hydraulic fracturing design in the Ordos Basin.

An improved nonlinear constitutive model for the magneto-elastic coupling behavior of ferromagnetic materials

Based on the micro-domain theory, the macro-thermodynamic relationship, and the effective field theory, an improved nonlinear constitutive model is established for ferromagnetic materials. The constitutive model includes new expressions of some nonlinear functions and high-order nonlinear functions and has simple expressions for some ferromagnetic materials. Compared with the existing models, the nonlinear model established in this paper has a great improvement in the prediction accuracy of the magneto-elastic coupling behavior. In other words, it can accurately predict the complicated nonlinear behaviors of magnetostriction and magnetization under the magnetic field and applied stress. Furthermore, it can correctly describe magnetostriction with high tensile stress and low magnetic fields, the complicated magnetostriction behavior with stress and middle magnetic fields, the complicated magnetization behavior with stress and high magnetic fields, and the maximum point of magnetostriction according to applied stress for ferromagnetic materials. A detailed analysis of the complicated nonlinear behaviors for ferromagnetic materials demonstrates the high effectiveness of the presented model.

Geodynamic prerequisites and reflection of signs of fluid migration in hydrogeochemical indicators of formation water in the Bukhara-Khiva region

The article describes the results of a study of changes in the composition and hydrogeochemical parameters of individual areas and fields of the Bukhara-Khiva region based on well materials. Vertical zonality of hydrogeochemical parameters associated with deep fluid flow and heat and mass transfer is noted. The manifestation of tectonodynamic conditions in the Mesozoic-Cenozoic history of the region, which served as a prerequisite for the formation of weakened zones (channels of deep heat and mass transfer) in the field of tensile stresses for the vertical migration of fluids and juvenile gases, is noted. A hydrogeological criterion for identifying zones of deep heat and mass transfer and vertical fluid migration is proposed. Keywords: wells; oil and gas; formation waters; fluids; hydrogeochemical indicators of formation waters; heat and mass transfer.

Regulation mechanism of giant magneto-impedance effect of multi-field coupling Fe-based alloy

Fe-based amorphous and nanocrystalline alloys are considered as the preferred dual-green energy-saving materials due to their unique magnetic properties, such as high permeability, low coercivity, and near-zero saturation magnetostriction. As such, they have received extensive attention in applications like magnetic core material for high-frequency transformers, common model chokes, ground fault interrupters, and rotors in motors, over the past decades. In this work, Fe&lt;sub&gt;64.8&lt;/sub&gt;Co&lt;sub&gt;7.2&lt;/sub&gt;Nb&lt;sub&gt;4&lt;/sub&gt;Si&lt;sub&gt;4.8&lt;/sub&gt;B&lt;sub&gt;19.2&lt;/sub&gt; (in atom percent) amorphous alloy ribbons are prepared by using the single roller quenching method, then subsequently subjected to multi-field coupling heating treatment in the air which includes heating by Joule heating effect and tensile stress field. Furthermore, the longitudinally driven giant magneto-impedance effect and magnetic domain structures of ribbons are observed by using 4294A impedance analyzer and magnetic force microscopy, respectively. The magneto-crystalline anisotropy field and stress anisotropy field of ribbons are analyzed by using X-ray diffraction, random anisotropy model, and numerical fitting. Meanwhile, the concept of magnetic anisotropy competing factor (&lt;i&gt;k&lt;/i&gt;) is proposed, from the viewpoint of magnetic anisotropy, a mechanism for regulating giant magneto-impedance effect of ribbons prepared with multi-field coupling is studied. It is found that the longitudinally driven giant magneto-impedance effect gradually transforms from the single peak to dome-like with tensile stress increasing. However, a spike and dome-like giant magneto-impedance effect appears during such transformation, which is composed of two parts: spike-like top and dome-like base. Based on the magnetic domain structure of ribbons, it is found that the typical stress-annealed transversal magnetic domain structure is observed in ribbons of &lt;inline-formula&gt;&lt;tex-math id="Z-20221115160531"&gt;\begin{document}$k \leqslant 0.147$\end{document}&lt;/tex-math&gt;&lt;alternatives&gt;&lt;graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="23-20221376_Z-20221115160531.jpg"/&gt;&lt;graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="23-20221376_Z-20221115160531.png"/&gt;&lt;/alternatives&gt;&lt;/inline-formula&gt;, while nucleation and splitting phenomenon of new domains are observed at the transversal magnetic domain wall in ribbons of &lt;i&gt;k&lt;/i&gt; &gt; 0.147. Both longitudinally driven giant magneto-impedance effect and domain structures provide evidence to support the competing inhibition effect of magnetic anisotropy which exists in Fe-based alloy ribbon. Therefore, it is suggested that Fe-based alloys exhibit excellent stress-sensitive properties that can be understood by the competing inhibition effects of magnetic anisotropy. It is further shown that the competing inhibition effect of magnetic anisotropy is the main reason for regulating the giant magneto-impedance effect of soft magnetic materials. This multi-field coupling Fe-based alloy has good application prospects in regulating magnetic properties of magnetic materials.

The qualitative analysis of warpage on residual stresses in wire arc additive manufacturing

Additive manufacturing (AM) is a fabrication method of parts and components, layer by layer, using a suitable high-density heat source. This process concedes to the user in fabricating the parts or components directly from a digital file. The application of high heat energy and a complex thermal cycle led to residual stresses during the fabrication. Generally, the top layer of the walls experiences tensile stresses, and this stress field provides a suitable environment for crack propagation in the components. The cracks inside the components deteriorate the functional life and quality of products. ER70S-6 commonly used welding wire as feedstock materials in wire arc additive manufacturing (WAAM) for structural application. Generally, maximum tensile stresses in the layers are limited to yield strength. These stresses cause bending distortion in the assembly, leading to warpage. The warpage and hardness have a direct relation with residual stresses. The compressive stresses in the parts have more hardness than the parts with a tensile residual stress field. The assembly warped due to the redistribution of the stress field. This article proposes a new deposition technique for reducing residual stresses in the in-situ condition. In addition, this novel deposition technique shall use to conduct a qualitative analysis of mitigation staregy for warpage in situ-state.

Dislocation-Mediated Hydride Precipitation in Zirconium.

The formation of hydrides challenges the integrity of zirconium (Zr) fuel cladding in nuclear reactors. The dynamics of hydride precipitation are complex. Especially, the formation of the butterfly or bird-nest configurations of dislocation structures around hydride is rather intriguing. By in-situ transmission electron microscopy experiments and density functional theory simulations, it is discovered that hydride growth is a hybrid displacive-diffusive process, which is regulated by intermittent dislocation emissions. A strong tensile stress field around the hydride tip increases the solubility of hydrogen in Zr matrix, which prevents hydride growth. Punching-out dislocations reduces the tensile stress surrounding the hydride, decreases hydrogen solubility, reboots the hydride precipitation and accelerates the growth of the hydride. The emission of dislocations mediates hydride growth, and finally, the consecutively emitted dislocations evolve into a butterfly or bird-nest configuration around the hydride.

Fracture Characteristics and Heat Accumulation of Jixianian Carbonate Reservoirs in the Rongcheng Geothermal Field, Xiong'an New Area

AbstractGeothermal energy plays an important role in urban construction of the Xiong'an New Area. Geothermal reservoir fracture distribution of the Mesoproterozoic Jixianian Wumishan Formation (Fm.) carbonate reservoir in the Rongcheng geothermal field are evaluated based on FMI log from Wells D19 and D21. The results show carbonate reservoir fracture density of Well D19 is 15.2/100 m, greater than that of Well D21 with a value of 9.2/100 m. Reservoir porosity and permeability of Well D19 are better than that of Well D21, and the water saturation is bimodally distributed. The movable fluid volume ratio (BVM) of Well D19 is 2% to 8% with some zones exceeding 20%, while the value of Well D21 is less than 4%. Therefore, reservoir fractures in Well D19 are more conducive to fluid flow. Reservoir fractures have a similar occurrence to normal faults, indicating that the tensile stress field controlled the formation of such fractures. Developed reservoir fractures provide a good channel for groundwater convection. The circulation of regional groundwater and the heat exchange between water and rock and the multiple heat accumulation patterns form a stable and high potential heat reservoir in the Rongcheng geothermal field.

Raman Study of Polycrystalline Si3N4 Irradiated with Swift Heavy Ions

A depth-resolved Raman spectroscopy technique was used to study the residual stress profiles in polycrystalline silicon nitride that was irradiated with Xe (167 MeV, 1 × 1011 cm−2 ÷ 4.87 × 1013 cm−2) and Bi (710 MeV, 1 × 1011 cm−2 ÷ 1 × 1013 cm−2) ions. It was shown that both the compressive and tensile stress fields were formed in the irradiated specimen, separated by a buffer zone that was located at a depth that coincided with the thickness of layer, amorphized due to multiple overlapping track regions. The compressive stresses were registered in a subsurface region, while at a greater depth, the tensile stresses were recorded and their levels reached the maximum value at the end of ion range. The size of the amorphous layer was evaluated from the dose dependence of the full width at half maximum (FWHM) (FWHM of the dominant 204 cm−1 line in the Raman spectra and scanning electron microscopy.

Effects of TiB2 Particles on the Microstructure Evolution and Mechanical Properties of B4C/TiB2 Ceramic Composite.

B4C/TiB2 ceramic composites reinforced with three size scales (average particle size: 7 μm, 500 nm, and 50 nm) of TiB2 were prepared by using a pressureless sintering furnace at 2100 °C under Ar atmosphere for 60 min. The results demonstrated that during the sintering process, TiB2 located on the boundaries between different B4C grains could inhibit the grain growth which improved the mass transport mechanism and sintering driving force. A semi-coherent interface between B4C and SiC was found, which is supposed to help to reduce the interface energy and obtain good mechanical properties of the B4C/TiB2 ceramic composite. On sample cooling from sintering temperature to room temperature, the residual tensile stress fields formed at the TiB2 interfaces owning to the thermo-elastico properties mismatched, which might have contributed to increase the ability of the sample to resist crack propagation. The results showed that the relative density, Vickers hardness, and fracture toughness of the composite with 20 wt.% submicron and 10 wt.% nano-TiB2 were significantly improved, which were 98.6%, 30.2 GPa, and 5.47 MPa·m1/2, respectively.

Microscopic origins of the crystallographically preferred growth in evaporation-induced colloidal crystals

Unlike crystalline atomic and ionic solids, texture development due to crystallographically preferred growth in colloidal crystals is less studied. Here we investigate the underlying mechanisms of the texture evolution in an evaporation-induced colloidal assembly process through experiments, modeling, and theoretical analysis. In this widely used approach to obtain large-area colloidal crystals, the colloidal particles are driven to the meniscus via the evaporation of a solvent or matrix precursor solution where they close-pack to form a face-centered cubic colloidal assembly. Via two-dimensional large-area crystallographic mapping, we show that the initial crystal orientation is dominated by the interaction of particles with the meniscus, resulting in the expected coalignment of the close-packed direction with the local meniscus geometry. By combining with crystal structure analysis at a single-particle level, we further reveal that, at the later stage of self-assembly, however, the colloidal crystal undergoes a gradual rotation facilitated by geometrically necessary dislocations (GNDs) and achieves a large-area uniform crystallographic orientation with the close-packed direction perpendicular to the meniscus and parallel to the growth direction. Classical slip analysis, finite element-based mechanical simulation, computational colloidal assembly modeling, and continuum theory unequivocally show that these GNDs result from the tensile stress field along the meniscus direction due to the constrained shrinkage of the colloidal crystal during drying. The generation of GNDs with specific slip systems within individual grains leads to crystallographic rotation to accommodate the mechanical stress. The mechanistic understanding reported here can be utilized to control crystallographic features of colloidal assemblies, and may provide further insights into crystallographically preferred growth in synthetic, biological, and geological crystals.

Numerical investigation on crack propagation and coalescence induced by dual-borehole blasting

Dynamic directional fracture of dual-borehole blasting is very vital to the rock fragmentation and final contour of some projects, such as the tunnel and slope. In this paper, a rock-like material, polymethyl methacrylate (PMMA), is utilized to explore the effects of borehole distance d, delayed time td, and guide hole type on crack propagation behavior under dual-borehole blasting through numerical simulations. To improve the deficiency of constitutive model and the post-failure response of brittle material and reduce the mesh dependency, a coupling scheme of Johnson-Holmquist (JH-2) model, failure criterion, and crack softening failure model is adopted here. First, the crack propagation results of single-borehole blasting well reproduced inner and outer actions of blasting, which proved the reliability of this scheme. For the dual-borehole blasting, it was found that the increase of borehole distance indeed penalized the crack coalescence and the length of crack produced at the common guide hole. Compared with the common guide hole, the grooved guide hole at d = 30 cm contributes more crack coalescences, which is independent of the delayed time; at d = 40 cm, the longer cracks are produced at grooved guide hole than common one and the crack coalescence is related to the delayed time. The grooved guide hole was more conducive to the coalescence and lengthening of crack. More importantly, the crack coalescence manner showed mutual, direct, and indirect ones, and two manners could coexist in one model. In addition, guide hole also could enrich the crack coalescence manner. Lastly, the crack stagger depends on the change of tensile stress at one crack tip into the compressive one at another one; the crack coalescence indicates tensile stress fields of two crack tips have no mutual influence.

Automated Quantitative Fractography of Silicate Glasses with Visual Analysis

ASTM C1678 outlines an approach to estimate the fracture strength of glasses and ceramics through the use of empirical relationships relating the strength to characteristic fractographic length-scales, such as the ‘mirror radius’. However, the process of measuring radii is subjective, and the relationship suggested by ASTM standards has been shown to be relatively inaccurate for flexural stress fields. This research introduces and tests a visual analysis algorithm to carry out the fractographic analysis of silicate glasses automatically and objectively. The fracture surfaces of various silicate glasses produced by both tensile and flexural stress fields were considered. First, optical images of the fracture surfaces were gathered and unique; descriptive features such as the shape of the ‘mirror-mist boundary’ were extracted using visual analysis tools. Next, a newly developed algorithm compared the processed images with a database comprised of fracture samples of known strengths, fracture toughness, stress fields, and geometric features. Lastly, dimensional analysis principles coupled with a broad, experimental set of over 2100 fracture surfaces was used to accurately estimate the strengths of the imaged fracture surfaces.

Evaluation of Coal Body Structures and Their Distributions by Geophysical Logging Methods: Case Study in the Laochang Block, Eastern Yunnan, China

The coal body structure is one of the key parameters in the exploration and exploitation of coalbed methane (CBM). Accurate identification of the structure of a coal seam is important for CBM exploration and development. In the present study, we collected coal seam logging data and drilling data from six CBM wells in the Laochang block in eastern Yunnan, China. Four logging curves, including gamma-ray logging (GR), density logging (DEN), acoustic travel time logging (DT) and compensated neutron logging (CNL), were selected. Principal component analysis was used to establish a geophysical identification approach for the coal body structures in the Laochang block. The geophysical identification results for the coal body structures were in good agreement with the actual coring data. We found that if the coal body structures score (F value) was less than 12, the coal seam belongs to Type I coal; otherwise, it is Type II coal. With increasing coal seam thickness, the proportion of Type I coal showed a decreasing power function trend. When coal seam thickness exceeded 1 m, it was dominated by Type II coal. The coal seams near well YW-04 had the highest degree of overall damage, followed by wells YW-02, YW-03 and YW-01. The coal seam in well YW-04 was affected by the superimposed regional and local tectonic tensile stress fields; the coal seam in well YW-02 was subject to the regional tensile stress field and the goaf, and the coal seams in wells YW-01 and YW-03 were subject to the joint effects of the regional tensile and local compressive tectonic stress fields. The distributions of the coal body structures in the Laochang block were the result of the combined effects of the coal thickness, goaf, tectonic type and tectonic stress field. These results may provide guidelines for the exploration and development of CBM in the Laochang block in eastern Yunnan. Furthermore, the scientific and quantitative evaluation method developed in this research can be applied to the identification of coal body structures in other CBM blocks worldwide.

Fracture analysis of plates and shells using FEM and XFEM

Fracture mechanics is the field of mechanics concerned with the study of propagation of cracks in materials and recognizes the role of cracks in the performance of structures leading to damage tolerant design approach. Cracks or crack like defects is observed in many structures which may lead to their catastrophic failure under a tensile stress field. In this paper, the structural integrity of plates with surface and embedded cracks is investigated using ABAQUS FEA code and the fracture parameter—stress intensity factor (SIF)—is evaluated. Convergence study is conducted to arrive at the optimum mesh parameters using both the conventional finite element method and the extended finite element method (XFEM). The FE model is validated by comparing FE results with published numerical solutions. The effect of varying crack depth and location on SIF is studied. The FE results matched well with the closed-form solutions and experimental results. It is observed that the crack depth and its location have significant influence on SIF. The conventional finite element method requires a mesh that conforms to the crack geometry, typically with a very detailed, focused mesh at the crack tip. The crack front must be defined explicitly and must specify the virtual crack extension direction in addition to matching the mesh to the cracked geometry. XFEM gives better result for cylindrical shells without mesh refinement around crack tip.

Atomic modeling of the segregation of vacancies on [formula omitted] dislocations in α-iron by diffusive molecular dynamics simulations

The interaction between dislocations and vacancies at finite temperature is crucial for many physical properties and phenomena in materials, such as vacancy segregation, strengthening effect, dislocation motion, and crystal plasticity. Conventional dislocation-vacancy interaction models use approximations based on elasticity theory and assumption that transition state energy can be deduced from the binding energy of the vacancies. The long-term vacancy diffusion near dislocation and the change of dislocation core induced by vacancy segregation are still difficult to capture. In this paper, we present the theoretical study on diffusion and segregation properties of vacancies near 111 edge or screw dislocation on slip planes of {110}, {112} and {123} in bcc iron. The calculations are performed with the distribution of vacancy concentration and dislocation-vacancy interaction energy as a function of distance from dislocation core using diffusive molecular dynamics (DMD). Meanwhile, the accompanying effects of the interaction on vacancy segregation, dislocation motion, and crystal plasticity are discussed. The vacancy diffusion near dislocation is a process highly anisotropic and inter-correlated towards equilibrium. The interaction of vacancies with the tensile stress field of edge dislocations is numerically stronger than that with the pure shear stress field of screw dislocations. The Peierls stress are calculated to reflect the effect of the vacancy segregation on dislocation motion. The slip planes of 111 dislocations have a significant influence on this interaction. With the slip planes changing from {110} to {123} to {112}, the absorption intensity of dislocation to vacancy and the ranges of the “effective interaction region” of both edge and screw dislocation decrease while the ranges of “absorption region” increases gradually. In addition, vacancy segregation produces a regulatory mechanism for the structure of dislocation core and promotes the transformation of dislocations on different slip planes to a more stable intermediate structure. This study visually presents the evolution of vacancies near dislocation, providing fundamental insights on the vacancy transport mechanisms which are essential for understanding dislocation-vacancy interaction, dislocation motion and plasticity of metallic materials.

Atomistic simulation of interaction between wedge disclination and self-interstitial atom in bcc tungsten

Molecular dynamics method has been employed to investigate the interaction between wedge disclination and self-interstitial atom in bcc tungsten. Long-range tensile stress field is shown around the disclination. The interaction energy between self-interstitial atom and the disclination ranges from −1eVto −6.13eV, which decreases with self-interstitial atom closer to the disclination core. Self-interstitial atoms around the disclination can be absorbed by the edge dislocations of the disclination, leading to a negative climb and thus reduction of the strain energy. It can be concluded that absorption of self-interstitial atoms by the wedge disclination is an energy downhill process, and disclination can serve as an effective sink for eliminating the radiation-induced self-interstitial atoms in bcc tungsten.

The effect of the shape and size of initial flaws on crack propagation in uniaxially compressed linear brittle materials

Explaining crack propagation in uniaxially compressed brittle solids is challenging because the complexity of such fracture makes it impossible to estimate the compressive capacity of a solid subjected to uniaxial compression using a well-defined, widely applicable formula. Localized tension is typically generated at the tip of a void in a solid under uniaxial compression, so we focus here on the geometrical possibilities of internal cavities and the impact of that geometry on crack propagation in a uniaxially compressed linear brittle solid. The study includes a review of the current understanding and limitations of knowledge of fracture in uniaxial compression and Finite Element based analyses of different initial void/cavity geometries and their impact on crack propagation. Analysis of crack propagation is carried out in terms of the mode I stress intensity factors associated with cracks propagating from different initial voids. Despite the analyses being limited to 2D, novel observations are discussed about the nature of crack propagation in uniaxial compression, confirming the complexity of this type of failure. The width (direct relationship), height (inverse relationship), size (direct relationship) and shape of the void are shown to be important in triggering crack propagation, but not the width-to-height ratio. An initial horizontal elliptical void with the major axis parallel to the applied compression and a minor axis 1/20 the length of the major axis was found to be the most critical void in terms of the likelihood to trigger cracks in uniaxial compression. Vertical elliptical voids were found to be less critical than all the other voids studied. The applicability of a stress intensity vs fracture toughness approach, as used to predict failure in tensile stress fields, is questioned.

Fatigue analysis of a bucket wheel by using Linear Elastic Fracture Mechanics

An analysis by using the concepts of the Linear Elastic Fracture Mechanics (LEFM) was conducted in order to study the crack propagation in the welded joint of a bucket wheel that failed at service after approximately one year of operation. Some aspects related to the welded joint were considered in the analysis, such as the occurrence of residual stresses in the structure, the magnification factor of the stress intensity factor (SIF) due to the weld geometry and crack closure phenomenon. Stress intensity factors were numerically obtained for the evaluated cracks, considering tensile and shear loads. Walker equation was used for determining the propagation rate. A fatigue life consistent with the estimation of the number of cycles until the failure of the bucket wheel was obtained when considering the propagation of a preexisting crack in the structure in a field of residual tensile stresses across the thickness of the plate and along the weld bead. It was evaluated that fatigue life based on S-N curves, for a weld detail similar to the weld joint under study, was higher than the estimated number of cycles until the bucket wheel failure, indicating that some defect may have remained after manufacture of the wheel and compromised its useful life.

Formation Mechanism of Residual Stress Field Induced by Surface Strengthening Process

Abstract The formation of the residual stress field that accompanies severe plastic deformation is analyzed in view of the crystal structure evolution and mechanical response of the material. The conclusion drawn is that elastic release is the fundamental cause of the residual compressive stress field in the near-surface layer, while the residual tensile stress field in the deep region is attributed to load conservation. The elastic strain, which is embodied by the offset of a metal atom to the equilibrium position of the lattice, varies with the depth of the material owing to the differentiated effects of elastic release and load conservation.

The deformation and failure mechanism of cylindrical shell and square plate with pre-formed holes under blast loading

The deformation and failure mechanism of cylindrical shells and square plate with pre-formed holes under blast loading were investigated numerically by employing the Ansys 17.0 and Ls-Dyna 971. To calibrate the numerical model, the experiments of square plates with pre-formed circle holes were modeled and the numerical results have a good agreement with the experiment data. The calibrated numerical model was used to study the deformation and failure mechanism of cylindrical shells with pre-formed circle holes subjected to blast loading. The structure response and stress field changing process has been divided into four specific stages and the deformation mechanism has been discussed systematically. The local and global deformation curves, degree of damage, change of stress status and failure modes of cylindrical shell and square plate with pre-formed circular holes are obtained, compared and analyzed, it can be concluded as: (1) The transition of tensile stress fields is due to the geometrical characteristic of pre-formed holes and cylindrical shell with arch configuration; (2) The existence of pre-formed holes not only lead to the increasing of stress concentration around the holes, but also release the stress concentration during whole response process; (3) There are three and two kinds of failure modes for square plate and cylindrical shell with pre-formed holes, respectively. and the standoff distance has a key influence on the forming location of the crack initiating point and the locus of crack propagation; (4) The square plate with pre-formed holes has a better performance than cylindrical shell on blast-resistant capability at a smaller standoff distance, while the influence of pre-formed holes on the reduction of blast-resistant capability of square plate is bigger than that of cylindrical shell.