We investigate the performance of van der Waals (vdW) functions in predicting elastic constants β cyclotetramethylene tetranitramine (HMX) energetic molecular crystals using density functional theory (DFT) calculations. confirm that accuracy is significantly improved vdW corrections with environment-dependent C6 together PBE and revised exchange-correlation functionals. The obtained PBE-D3(0) calculations yield most accurate mechanical response β-HMX when compared experimental stress-strain...

There are a large number of materials with mild stiffness, which not as soft tissues and strong metals. These semihard include energetic materials, molecular crystals, layered van der Waals crystals. The integrity mechanical stability mainly determined by the interactions between instantaneously induced dipoles, so called London dispersion force or force. It is challenging to accurately model structural properties these in frame density functional theory where non-local correlation...

Because the initial speed of seeds leaving seed disk is too high, they collide and bounce off inner wall guide tube, resulting in poor sowing quality when corn sown at high speeds above 12 km/h. This study clarifies primary factors affecting stability receiving accuracy entering cavity, establishes dynamic model clamping, transportation, releasing, investigates belt-type high-speed guiding device with system as research object. It also proposes an improved method adding herringbone lines on...

In the coal and rock dynamic disasters, such as burst, load damage often acts simultaneously on combined mass. Based split‐Hopkinson pressure bar (SHPB) test of with a bullet velocity 4.590–8.791 m/s, numerical model four kinds different sandstone‐coal‐sandstone ratios, including 1 : 1, 2 2, is investigated. A finite element software (LS‐DYNA) Holmquist–Johnson–Cook (HJC) constitutive are employed in these regards. The stress waveform, oscillation phenomenon wave, process specimen impact...

Landslides triggered by seismic loading pose a great threat to human lives, property, and infrastructure. This paper embeds unified constitutive model in the smoothed particle hydrodynamics (SPH) method analyzes initiation process of landslides. A wave is applied bottom boundary particles imposing velocities calculated using wave. The set as no-slip free field chosen reduce reflection. reliability developed SPH first validated simulation benchmark problem thin plate oscillation stability...

Mastering the high strain characteristics at cryogenics and constructing an accurate constitutive model are critical for establishing a cryogenic cutting simulation of Ti-6Al-4V alloy. The traditional is inadequate accounting conditions. In this paper, split Hopkinson pressure bar (SHPB) experiments conducted, specifically alloy, to develop modified Johnson–Cook (J–C) that incorporates effect. A coupled two-dimensional orthogonal finite element involving temperature displacement was...

Aluminized explosives have been applied in military industry since decades ago. Compared with ideal such as TNT, HMX, RDX, aluminized feature both fast detonation and slow metal combustion chemistry, generating a complex multi-phase reactive flow. Though employed for long time, the mechanism underneath chemical process is still not thoroughly understood. In this paper, smooth particle hydrodynamics (SPH) method incorporated ignition growth model, afterburning model has proposed simulation of...

Abstract This paper evaluates several key approaches for their impact on the development of insensitive munition (IM) with special emphasis fuze. The effect these thermal vulnerability a fuze is studied and evaluated by finite element analysis. These include changing proportion desensitizing agent, replacing charge, shell material, adding heat insulation coating. First, cook-off test plastic-bonded explosive number-5 (PBXN-5) squib tube simulated abaqus compared results to validate soundness...

Abstract A tracer technology system was integrated with AICD/ICD completions in 2 horizontal offshore wells a dual objective to assess performance of each individual inflow control device and obtain long-term dynamic data the well profile. As measure water control, ICD (Inflow Control Device) technique is widely applied eastern oilfield South China Sea, AICD (Autonomous Inflow also gaining wider recognition. At same time, it very difficult evaluate application effect ICD/AICD, there no...

Abstract Salt cavern gas storage typically involves frequent multi-cycle injection and production, resulting in cyclic loading of the salt system. The casing shoe, as one most vulnerable components, exhibits fatigue failure under loading, posing risk engineering accidents, including bond between cement sheath formation, collapse, leakage. However, there has been limited research on design shoe heights for storage. Therefore, this paper, casing-cement sheath-strata assembly was determined...

ABSTRACT: Swab/Surge pressure will increase the risk of wellbore stability such as lost circulation, collapse, kicks, and even blowouts, particularly in formations with narrow safe mud weight windows. The existing studies for predicting swab/surge pressures only consider variations induced by tripping hardly effects pump circulation during tripping. This paper presents a new steady-state model based on slot geometry. aims to predict circulation. Meanwhile, mitigate impact fluctuation...

The numerical study of detonation high explosives has been the interest researchers over decades. Due to its special advantages in tracking free surface and dealing with large deformation, smoothed particle hydrodynamics (SPH) a powerful tool investigate phenomenon. SPH is Lagrangian mesh-free method extensive applications fluid mechanics solid mechanics. In early development method, artificial viscosity introduced suppress unphysical fluctuation. However, parameters often need be tuned for...

It is rather difficult to observe, record and analyze the pore-collapse-induced initiation of a 1,3,5,7-tetranitro-1,3,5,7-tetrazocane or HMX crystal via experiment because it an extreme phenomenon involving multiphysics (such as shock, phase change HMX) chemical reactions (thermal decomposition occurring in microseconds even nanoseconds. Herein, mechanical-thermal-chemical coupled finite element model proposed simulate pore collapse under shock loading at velocities 500 m/s. A viscoplastic...