scholarly journals Examination of Lightning-Induced Damage in Timber

2021 ◽  
Author(s):  
Jingxiao Li ◽  
Jing Li
Keyword(s):  
Shock Wave ◽  
Temperature Rise ◽  
Damage Mechanism ◽  
Lightning Strike ◽  
Low Density ◽  
Damage Area ◽  
Wave Effects ◽  
Building Timber ◽  
Damage Depth ◽  
The Ancient Chinese

The ancient Chinese architectures were constructed using timber as the main building material. Considering that the lightning strike is the primary natural cause of damage to ancient building, the lightning strike damage mechanism of ancient building timber and the related influencing factors are investigated using the representative timber materials from the ancient building. The burning of timber was mainly caused by the heat of lightning arc. The splitting and damage pit of timber were mainly caused by the mechanical force generated by the temperature rise of the injected by lightning current and air shock wave effects of the lightning. These ways all played in different roles under different conditions. The higher the water content of timber was, the easier it was to crack, and the greater the damage depth and the larger the damage area were. It was easy to burn for the dry timber or the loose timber with low density, but it was difficult for the thick timber. When the wood was too thin, the lightning air shock wave could cause damage. This research may provide reference for protection of ancient timber architecture from possible damage caused by lightning.

Electron microscopy study of shock synthesis of silicides

1993 ◽  
Vol 51 ◽  
pp. 1162-1163
Author(s):  
Kenneth S. Vecchio
Keyword(s):  
Shock Wave ◽  
Plastic Deformation ◽  
Close Contact ◽  
Microscopy Study ◽  
High Energy ◽  
Electron Microscopy Study ◽  
Powder Materials ◽  
Porous Powder ◽  
Wave Effects ◽  
Wave Passage

Shock-induced reactions (or shock synthesis) have been studied since the 1960’s but are still poorly understood, partly due to the fact that the reaction kinetics are very fast making experimental analysis of the reaction difficult. Shock synthesis is closely related to combustion synthesis, and occurs in the same systems that undergo exothermic gasless combustion reactions. The thermite reaction (Fe2O3 + 2Al -> 2Fe + Al2O3) is prototypical of this class of reactions. The effects of shock-wave passage through porous (powder) materials are complex, because intense and non-uniform plastic deformation is coupled with the shock-wave effects. Thus, the particle interiors experience primarily the effects of shock waves, while the surfaces undergo intense plastic deformation which can often result in interfacial melting. Shock synthesis of compounds from powders is triggered by the extraordinarily high energy deposition rate at the surfaces of the powders, forcing them in close contact, activating them by introducing defects, and heating them close to or even above their melting temperatures.

Shock wave effects during a Taylor test

2006 ◽  
Vol 134 ◽  
pp. 1065-1070
Author(s):  
E. Lach ◽  
M. Scharf
Keyword(s):  
Shock Wave ◽  
Taylor Test ◽  
Wave Effects

Analysis Techniques for Modeling the Pressure Wave Effects of Guillotine Ruptures of Steam Lines

2011 ◽  
Author(s):  
Charles Becht ◽  
Frederick J. Moody
Keyword(s):  
Shock Wave ◽  
Propagation Model ◽  
Shock Propagation ◽  
Cfd Model ◽  
Analysis Techniques ◽  
Wave Effects ◽  
Fluid Properties ◽  
Potential Damage ◽  
Pipe Geometry ◽  
Propagation Properties

The rupture of a pipe containing gas or steam at high pressure will cause a shock wave. In order to assess the potential damage that such a shock wave may cause to the surrounding structures, systems and components, it is necessary to determine the amplitude and propagation properties of the shock. A CFD model has been developed for the purpose of predicting shock propagation transients resulting from a sudden pipe rupture in terms of the fluid properties, pipe geometry, and surroundings. A simplified shock propagation model also is included, which offers verification of the CFD model results.

Shock wave effects on a turbulent flow

1991 ◽  
Vol 3 (7) ◽  
pp. 1792-1806 ◽  
Author(s):  
Douglas Rotman
Keyword(s):  
Shock Wave ◽  
Turbulent Flow ◽  
Wave Effects

scholarly journals Малогазовая детонация в низкоплотных механоактивированных порошковых смесях

2019 ◽  
Vol 89 (6) ◽  
pp. 821
Author(s):  
С.А. Рашковский ◽  
А.Ю. Долгобородов
Keyword(s):  
Experimental Data ◽  
Shock Wave ◽  
Energy Release ◽  
Powder Mixture ◽  
Powder Compaction ◽  
Mutual Friction ◽  
Low Density ◽  
Powder Mixtures ◽  
Release Wave ◽  
Fuel Particles

Experimental data on supersonic self-sustaining propagation of the energy release wave in low-density mechanically activated powder mixtures are analyzed. Various mechanisms that may be responsible for this process are analyzed, and a mechanism for the detonation-like propagation of the reaction in powder mixtures is proposed. It is shown that under certain conditions this process has all the signs of detonation and should be recognized as one of the types of detonation. It is shown that this type of detonation is fundamentally different from the classical "ideal" detonation, for example, in gases: instead of a shock wave, a compaction wave propagates through the powder mixture, in which there is basically no compression of the particle material, but powder compaction occurs due to the mutual rearrangement of particles. In this case, the initiation of a chemical reaction occurs due to the mutual friction of the oxidizer and fuel particles in the powder compaction wave.

scholarly journals NUMERICAL ASSESSMENT OF THE SELECTED SUPPORTING ELEMENT CARRYING CAPACITY OF CRITICAL INFRASTRUCTURE FACILITY / SZACOWANIE NUMERYCZNE NOŚNOŚCI WYBRANEGO ELEMENTU KONSTRUKCYJNEGO OBIEKTU INFRASTRUKTURY KRYTYCZNEJ

2013 ◽  
Vol 26 (1) ◽  
pp. 29-42 ◽  
Author(s):  
Jerzy Małachowski ◽  
Marian Klasztorny ◽  
Łukasz Mazurkiewicz ◽  
Damian Kołodziejczyk ◽  
Tadeusz Niezgoda
Keyword(s):  
Shock Wave ◽  
Modeling And Simulation ◽  
Energy Absorption ◽  
Carrying Capacity ◽  
Critical Infrastructure ◽  
Cylindrical Panel ◽  
Numerical Assessment ◽  
Wave Effects ◽  
Protective Cover ◽  
Supporting Element

Abstract Issues related to critical infrastructure safety is highly demanding in aspect of newly projected systems. In this paper a problem of modeling and simulation of the supporting structure behavior of critical facility (without or with proposed protective cover) loaded with a shock wave is presented. Authors assume that two different phenomena will be responsible for minimization of shock wave effects: flow around cylindrical panel and energy absorption by panel structure. In this paper research focuses on the description and analysis of the process of explosion near the supporting elements and the blast interaction with the structure.

Lightning strike damage on the composite laminates with carbon nanotube films: Protection effect and damage mechanism

2019 ◽  
Vol 168 ◽  
pp. 342-352 ◽  
Author(s):  
Jikui Zhang ◽  
Xianglin Zhang ◽  
Xiaoquan Cheng ◽  
Yanwei Hei ◽  
Liying Xing ◽  
...  
Keyword(s):  
Carbon Nanotube ◽  
Composite Laminates ◽  
Damage Mechanism ◽  
Lightning Strike ◽  
Protection Effect ◽  
Nanotube Films

Damage Mechanism of Broad-narrow Joint of CRTSII Slab Track under Temperature Rise

2019 ◽  
Vol 23 (5) ◽  
pp. 2126-2135 ◽  
Author(s):  
Xiaokai Liu ◽  
Wenhao Zhang ◽  
Jieling Xiao ◽  
Xueyi Liu ◽  
Wei Li
Keyword(s):  
Temperature Rise ◽  
Damage Mechanism ◽  
Slab Track

Shock waves in a liquid containing gas bubbles

1958 ◽  
Vol 243 (1235) ◽  
pp. 534-545 ◽  
Keyword(s):  
Shock Wave ◽  
Shock Waves ◽  
Rarefaction Wave ◽  
Temperature Rise ◽  
Compression Wave ◽  
Liquid Mixture ◽  
Propagation Speed ◽  
Plane Wall ◽  
Shock Propagation ◽  
Wide Range

Considerations of continuity, momentum and energy together with an equation of state are applied to the propagation of plane shock waves in a gas + liquid mixture. The shock-wave relations assume a particularly simple form when the temperature rise across a shock, which is shown to be small for a very wide range of conditions, is neglected. In particular, a simple relation emerges between the shock propagation speed and the pressure on the high-pressure side of the shock, the density of the liquid and the relative proportions, by mass and volume, of gas and liquid in the mixture. It is shown from entropy considerations that a rarefaction wave cannot propagate itself without change of form, and it is argued that a compression wave can be expected to steepen into a shock wave. Consideration of the collision between two normal shock waves, moving in opposite directions, suggests that the strengths of the two shocks are unaltered by the interaction between them. This implies, in particular, that, when a shock impinges normally on a plane wall, the pressure ratio across the reflected shock is equal to that across the incident shock. When the mass ratio of gas to liquid in the mixture is allowed to tend to infinity, the various shock-wave relations for a mixture, derived with the temperature rise across the shock neglected, assume the same limiting form as the corresponding relations for a perfect gas when the ratio of specific heats tends to unity. The theoretical discussion has been illustrated by experiments with a small gas + liquid mixture shock tube. Samples of the records, obtained when the passage of a shock changes the amount of light transmitted through the mixture to a photoelectric cell, illustrate the steepening of a compression wave and the flattening of a rarefaction wave. Measurements confirm the theoretical relation for the propagation speed of shock waves. Reasonably good experi­mental confirmation is also reported of the theoretical predictions for the pressure which arises following the normal impact of a shock wave on a plane wall.

Failure Analysis of a Ruptured Final Reheat Tube

2007 ◽  
Author(s):  
S. M. French
Keyword(s):  
Shock Wave ◽  
Charpy Impact ◽  
Charpy Impact Test ◽  
Incident Shock ◽  
Incident Shock Wave ◽  
Back Surface ◽  
Damage Area ◽  
Local Overheating ◽  
Spalling Failure ◽  
The Impact

Two damaged final reheat tubes from a 30 year old supercritical unit were submitted to the laboratory for evaluation following the discovering of a failure of one of the tubes after deslagging operations; a third, dented tube was left in service. The 304H stainless steel tubes were installed in 1990 when the reheater was replaced. The bulk microstructure of both tubes shows evidence of sensitization, which is not unusual given this application (reheater). The failed tube appears to be an intergranular separation that started either subsurface or at the ID, propagating to the OD surface. The sensitization of the steel apparently made the material susceptible to corrosion as well as significantly reduced the impact strength of the material to 10–15% of its estimated original level (verified by Charpy impact test). Examination of the dented tube (#101A) showed a subsurface plane of damage some 30 mils from the ID surface, running parallel to the surface. The damage consisted of intergranular separation, caused by the impact loading event, and referred to in the literature as an “attached spalling failure”. Spalling failures occur when the shock wave is reflected from the back surface (the ID surface of the tube), interacting with the incident shock wave as a stress wave. When the magnitude of this tensile stress exceeds the inherent strength of the material, failure occurs. The overall area of the attached spalling failure is being investigated; the concern there is if it is exceptionally large, it may provide a thermal barrier to heat transfer from the OD to the ID and result in a local overheating failure. Within the metallographic sample, however, the damage area was quite small and therefore did not appear to be an immediate issue. The long-term suitability of tube 105A, which remains in service with a dent induced by the same deslagging process that damaged tubes 101A and 103A, is doubtful and should be addressed during the Fall 2006 boiler overhaul. For the shortterm, the assumption was made that cracking due to the deslagging impact would be oriented similar to non-failed tube and extension of these fissures to failure between Spring 2006 and the Fall outage is not expected.

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