The influence of stress wave on the impact fracture strength of cracked member

Maekawa, Ichiro

doi:10.1016/j.ijimpeng.2004.11.004

Cited by 6 publications

(4 citation statements)

References 3 publications

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“…Then, the theoretical expression on the degradation of dynamic shear strength can be obtained. The Coulomb-Navier criterion considers that the shear failure along one side of rock joints is controlled not only by shear stress but also by normal stress [45]. The failure of 3 Geofluids rock joints does not occur along the plane with maximum shear stress but ruptures along one of the faces where shear stress and normal stress reach the most unfavorable combination.…”

Section: Theoretical Expressionmentioning

confidence: 99%

Dynamic Shear Strength of Rock Joints and Its Influence on Key Blocks

Wang

Xiu

2019

Geofluids

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Shear strength deterioration of rock joints and its induced instability of key blocks subjected to dynamic disturbance constitute the mechanism of many geological disasters such as rockburst, landslide, and rockfall. In this study, the influence of dynamic disturbance on rock joints was quantified in the form of stress, of which model was established by quasistatic method. The dynamic shear strength of rock joints was analyzed theoretically following the Coulomb-Navier criterion and further investigated experimentally by split Hopkinson pressure bar (SHPB) tests with impact velocities of 4.850 m/s, 8.722 m/s, 12.784 m/s, and 16.935 m/s. The effect of engineering disturbance on shear strength of rock joints was measured, and a degradation coefficient was used to describe it quantitatively. Considering the degradation of dynamic shear strength of rock joints and its influence on block stability, the method for determining key blocks under dynamic disturbance was given. Implementing this method into the program of Geotechnical Structure and Model Analysis-3D (GeoSMA-3D) developed by the authors’ team, the visualization of key blocks was achieved. From theoretical analysis and experimental investigation, it was figured out that the shear strength of rock joints is degraded under dynamic disturbance. The degradation of friction angle becomes more sensitive than that of cohesion. Additionally, numerical results show that the number of key blocks was increased with the increasing impact velocities.

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Section: Theoretical Expressionmentioning

confidence: 99%

Dynamic Shear Strength of Rock Joints and Its Influence on Key Blocks

Wang

Xiu

2019

Geofluids

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“…It is noteworthy that scale effect is among the determinant qualitative factors for problems of stresses and fracture in impact interaction (see e.g. [10,11]): the structure element under impact loading is destroyed by stresses whose level is formed due to superposition of waves reflected from boundary surfaces. The classical Hertz theory of collision is known to be applicable in dynamics at large time values, i. е. after the wave processes have faded in the solid.…”

Section: An Axisymmetric Contact-impact Problem Is Considered For An mentioning

confidence: 99%

Impact indentation of a rigid body into an elastic layer. Axisymmetric problem

2011

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An axisymmetric contact-impact problem is considered for an elastic layer subjected by normal indentation of a rigid body. An exact analytical solution is obtained in the case1. Introduction. This paper is the continuation to the axisymmetric case of the plane problem analyzed in [9]. The introduction presented in [9] could be practically completely replicated herein, as well as sited works within [9]. With analytical approaches in mind, we refer review [1] reflecting the multitude of studies of a body's impact interaction with elastic and liquid media, while numerical approaches (primarily the method of finite elements) can be found in review [17]. A generalizing monograph in the field of contact interaction [3] is devoted to the development of analytical approaches to the solution of problems about the action of impact on an elastic medium. In the common case, the indentation problem is formulated as a unsteady-state mixed initially-boundary elasticity problem with an unknown (temporally varying) boundary, which must be determined in the course of the solution. The problem statement includes:· equations of dynamic deformation of the impacted solid; · the equation of the indenter motion; · the ratio presenting the resistive force (drag) as a function of contact stresses on a priori unknown contact surface; · the equation connecting the contact zone size with the indenter displacement, · the corresponding boundary and initial conditions; The overwhelming majority of publications (at least of those in which analytical methods are used) are devoted to the problem of impact by rigid or deformable indenter against a halfspace that precludes the possibility of analyzing the waves reflected from the boundaries of the impacted solid. Studies of indenter interaction with solids of finite size are much less represented. Positing such a problem appears topical in the practical aspect as well -in particular, in view of the wide use of laminate materials in modern aircraft and shipbuilding. It is noteworthy that scale effect is among the determinant qualitative factors for problems of stresses and fracture in impact interaction (see e.g. [10,11]): the structure element under impact loading is destroyed by stresses whose level is formed due to superposition of waves reflected from boundary surfaces. The classical Hertz theory of collision is known to be applicable in dynamics at large time values, i. е. after the wave processes have faded in the solid. The Saint -Venant wave theory of rod collision is well developed only for one-dimensional or quasi one-dimensional problems and does not take into account energy transfer in directions different from the impact one. The foresaid evaluates the motivation of the presented work devoted to the construction and investigation of more adequate models and methods for dynamic processes of indentation. This paper, in similar to [9], consists of two parts: in the first one a precise analytical solution of the problem is built of the indentation with a constant impact velocity of an smoot...

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“…In this paper, a theoretical analysis and computer simulation are presented. The theoretical analysis is carried out to determine the impact stress wave propagating in an air percussive rotary bit and the effect of the stress wave on bit fracture during propagation based on stress wave theory, since tress wave theory is widely used in impact analysis [15,16] and drilling field [17,18]. Additionally, a finite element simulation is carried out by building a model of an air hammer piston, drill and rock, defining material parameters, meshing and defining boundary conditions, clarifying propagation characteristics of the impact stress wave, analyzing stress characteristics of the bit matrix under different conditions (same drilling pressure and same piston speed, different drilling pressure and same piston speed and same drilling pressure and different piston speed) and finding the main factors of bit matrix fracture.…”

Section: Introductionmentioning

confidence: 99%

Fracture mechanism of air percussive rotary bit matrix based on impact stress wave theory

Huang¹,

Ma²,

Qiu³

et al. 2017

J. vibroeng.

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An air percussive rotary bit is a key component of air percussive rotary drilling technology, and its fracture failure seriously affects the safe operation and economic efficiency of drilling. This paper presents (1) theoretical analysis of the impact stress wave propagating in the air percussive rotary bit and effect of the stress wave on bit fracture and (2) finite element simulation study based on the stress wave theory which builds a model of the air hammer piston, drill and rock, defines material parameters, meshes and defines boundary conditions, clarifies propagation characteristics of the impact stress wave, analyzes stress characteristics of the bit matrix under different conditions (same drilling pressure and same piston speed, different drilling pressure and same piston speed and same drilling pressure and different piston speed) and determines the main factors of bit matrix fracture. The correctness of the theoretical analysis was verified with simulation results and fundamental ways of preventing bit fracture failure were proposed to provide a theoretical basis for the structural optimization design of a new bit. The results show that a bit section mutation is the root cause for the shock of the impact wave and the change in nature of the wave during propagation. The tensile wave is the root cause for bit matrix fracture, and a breakage is the most serious at stomatal interchanges. With increasing drilling pressure and piston speed, the rate of increase in the peak stress of the bit matrix increases, leading to early fatigue fracture of the bit matrix. The fracture of the bit matrix can be reduced, and the bit life can be extended by rationally designing the bit sectional structure parameters, ensuring that the bit withstands the effects of the compression wave so as to reduce the formation of a tensile wave, and rationally choosing drilling process parameters (such as drilling pressure and air pressure).

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The influence of stress wave on the impact fracture strength of cracked member

Cited by 6 publications

References 3 publications

Dynamic Shear Strength of Rock Joints and Its Influence on Key Blocks

Dynamic Shear Strength of Rock Joints and Its Influence on Key Blocks

Impact indentation of a rigid body into an elastic layer. Axisymmetric problem

Fracture mechanism of air percussive rotary bit matrix based on impact stress wave theory

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