Papers by Keyword: Impact Load

Abstract: During the moving stage of the projectile, the impact load produced by the detonation of the explosive powder acts on the ribbon, causing the plastic band deformation to occur rapidly and the surface temperature rapidly increases. In this paper, the evolution mechanism of the plastic deformation of brass band is studied, and the recrystallization process of the surface metal is still at the meso-scale scale. The recrystallization and grain growth stage sexual characteristics.

Abstract: Stress-strain analysis of a solid-propellant rocket engine is the subject of this study. A chosen material is selected in order to ensure its maximum strength at minimum weight of the engine. The airframe of the rocket engine is a thin-walled structure, which consists of cylindrical and spherical parts. The dynamic behaviour analysis of this thin-walled structure under the action of impact loads is performed. The anisotropic material model and dynamic properties of the shell material are taken into consideration to solve the underlying problem.

Abstract: The article presents a description of the impact block shear test method of adhesive joints. Based on ISO 9653 and literature a pendulum machine was upgraded to make impact strength tests of adhesive joints and validation studies were conducted to determine the parameters of instrumentation and block samples. As a result of the experiments a range of the usable length of the adhesive joint and methods of adhesive joints preparation was selected, and it was determined the adopted method of attachment of the sample in the holder and the pendulum durability. A series of tests on adhesive joints were conducted using samples bonded of adhesive composition Epidian 57 with Z1 hardener for one bondline thickness. Preliminary findings from the research will be used in subsequent, relevant research.

Abstract: More and more construction of tunnel engineering in karst region. Karst influence on tunnel engineering in deformation and instability, it often leading to Partial collapse, impellers, rock fall in the tunnel excavation or after work. For through large Karst cave tunnel, it will give great harm to tunnel, adjacent structures and injuries and consequence is very serious when faced with karst collapse occurs. The paper is based on engineering example of XieGiadong cave tunnel, the research results has important value for engineering construction and protection of resources. For example, the tunnel lining structure under the action of impact load produced large deformation and the overall shear failure and the process is ephemeral. Tunnel in the process of impact contact to destroy only less than 0.1 S, The vertical displacement of 2.88 m, the horizontal displacement of 0.8 m, fall since the collapse of rock mass to the maximum contact force of the contact with the tunnel 7000000KN.

Abstract: Elements of aircraft that are in direct interaction with the environment are exposed to the destructive effects of weather phenomena and the factors influencing them, as well as local environmental phenomena. One such factor is ultraviolet radiation emitted by the sun. This article presents the results of the influence of solar radiation (UV) on the strength properties of laminates with different types of reinforcement. The composites are susceptible to impact damage; therefore, to investigate the effect of UV radiation on such damaged composite, part of the samples were subjected to impact loads. The composites were made of the epoxy resin Epidian 52 with hardener Z1, and reinforced with glass fabric and carbon fabric. In order to carry out the research, we designed two devices – one for the production of low-energy impact and a second device to expose composite on UV radiation. As a result of studies, it was found that the UV radiation has a negative impact on the aesthetic qualities of the composite as well as the flexural strength of the materials. The decrease in strength of the samples subjected to shock loads and the influence of UV radiation is at a level slightly above 50%.

Abstract: In this paper, the effects of Cr content and impact load on the microstructure and properties of High Manganese Steel (HMS) were investigated. The results show that the hardness of HMS was increasing when the Cr content increased, but the hardness was not much changing when the Cr contents changed from 2% to 2,5% of weight. Under the impact load, the microstructure and the hardness were changed also. The Cr content effected on the depth of transition layer on surface under the impact load and the twinning occurred during impacting load.

Abstract: Pavements of airdromes, ports and container terminals, logistics terminals, industrial areas, parking lots, waste recycling areas and etc. are affected by static and impact loads. These kinds of loading differ from typical loading of roads. Due to it, pavements affected by static and impact load are design by special models according to the main distresses – permanent deformations and thermal cracking. For this purpose, there are discussed characteristics conditioning performance of pavements affected by static and impact load.

Abstract: A numerical approach is carried out to investigate the dynamic behavior of the CFRP strengthened pressure pipes subjected to impact load. In the FE analyses, Johnson-cook model is used to simulate metal subjected to large plastic strains and high strain rates, the fluid and pipe interaction is modeled by the surface-based fluid cavity to include the coupling effect between the deformation of the pipe and the internal pressure. Besides, the Hashin damage model is used to predict the damage of CFRP. The objectives of the numerical simulations are to capture the measured forming and crash history of the CFRP strengthened pressure pipes and gain an insight into the dynamic behavior of CFRP strengthened pressure pipes subject to impact load. The effects of internal pressure and the thickness of the CFRP are investigated, providing a detailed understanding of parameter sensitivity.

Abstract: This paper deals with the fabrication of test specimens of Glass fiber reinforced plastic (GFRP), Carbon fiber reinforced plastic (CFRP), Glass-Carbon fiber reinforced plastic (G-CFRP) and Carbon glass fiber reinforced plastic (C-GFRP) by using hand layup method. The low velocity point load setup was fabricated and fixed in the milling machine by using cam pointer arrangement. The specimens have been subjected to the low velocity point load for specific duration by exposure time such as 0,15,30,45 and 60 minutes. Then impact and DMA tests are also carried out for the above specimens. From the DMA test results it was found that the storage modulus and loss factor of GFRP specimen are high compared with others. Izod impact test result shows that impact strength of G-CFRP specimen is high. The flexural results reveals that among the four types of laminates CFRP gives higher order of flexural strength and modulus compared to the others

Abstract: To simulate the fracture of the coal under impact load, uniaxial pressure test of coal which retrieved from KongZhuang coal mine-DaTun coal and electricity Company of China coal group was done in the manner of strain control which rest with a function of uniform variable acceleration. Through researches on the stress-strain relationships and acoustic emission characteristics, the relationship between ring count rate and time series was founded, and the process before failure of coal was divided into four stages: low-level ringing count rate, higher level, highest level and peaceful period. Through the comparison and analysis, it is founded that acoustic emission characteristics in the stage of higher level of ringing count rate can be regarded as a basis for the prediction of coal fracture. According to three obvious rise stages of acoustic emission signal in the process before failure of coal, growth factor of climbing speed is introduced and the values are calculated between 2 to 4, and it is conferred that the value of is proportional to compressive strength of coal and loading rate. It is of great significance for the prediction of coal fracture by acoustic emission characteristics in the stage of new cracks.