Mechanical Properties Of Pmma Under Combined Stress And Nano-sized

Along with society’s progress and the development of science andtechnology, people on the material in the national construction, especially thedefence and aerospace aspects put forward higher requirements. Because oforganic glass has good mechanical properties, physical properties, chemicalproperties and processing performance, thus in the aerospace, automotive,construction, optical instruments, medical equipment, electronic and otheraspects have a wide range of applications. In recent decades, with thedevelopment of science and technology, the need of life, PMMA was appliedoptics instruments, medical equipment, electronics and other emerging areas,more and more wide prospect of application. Although the research on themechanical behavior of organic glass is now a very important field of study, butdue to limitations such as experimental method, the researchers on themechanical properties of composite materials under load and failure moderesearch co., LTD. In addition, because the organic glass was applied opticsinstruments, medical equipment, new fields such as electronics, and moretoward miniaturization development, so the mechanical properties of thematerial under the nanoscale is also our focus of concern.In this paper,in order to study the mechanical properties of PMMA under compression-shear composite load and nano-sized. Through the universalmaterial experiment machine, SHPB, Nano indenter G200three experimentalapparatus for inclined thin hexahedron, oblique cylinder sample and organicglass sheet through experimental study. Specific work is as follows:(1) By universal material testing machine for organic glass respectivelydifferent morphology of the thin plate specimen(regular hexahedronspecimen,oblique hexahedron specimen and hat specimen) under uniaxialcompression, in order to produce organic glass under different experimenttechnology of deformation mode(uniaxial compression, compression-shear,pure shear). Differences in different loading condition which lead to the failuremechanism of causing material show different mechanical properties. Inaddition on mechanical properties of the specimens under different Angleanalysis, it is concluded that: In the compression-shear loading compositematerials presents the obvious phenomenon of shear strengthening.In addition,by observing the morphology of the specimens after test, it is concluded thatdeformation of the specimen under different load characteristics, and throughthe analysis of the stress state of compression loading and shear loadingpressure specimen failure is mainly shear yield, and shear stress loadingspecimen is mainly due to tensile failure. At the same time, through the stressanalysis explains the causes of the formation of shear yield zone.(2) By universal material testing machine and SHPB different cylindricalspecimens of organic glass (straight cylindrical, oblique cylinder, hat specimen) at different loading rate (v=9.2m/s,0.4mm/s,0.04mm/s), different inclinedangles (5°,10°,15°,20°,25°,30°), different experimental technology(uniaxial compression, the compression shear and pure shear) system ofmechanical performance of the material under analysis. The followingconclusions: in uniaxial compression, compression-shear, pure shear underthree kinds of experimental technology, material all showed typical strain ratesensitivity. Main performance characteristics for the strain rate, the greater theyield limit. In addition to uniaxial compression and compression-shear load, v=0.4mm/s, v=0.4mm/s material characterized by ductile deformation, v=9.2m/s when the material is brittle deformation. Under the compression-composite shear load, with the increase of slope Angle, the yield limit. And in0°to30°, the yield limit under different loading rate linearly decreasing, and thehigher the loading rate, the faster a linear gradient. Under the same loading rate,the slope Angle, the greater the specimen are more likely to yield, this is mainlydue to the tilt Angle, the greater the shear stress. In addition under the sameslope Angle, the smaller the loading rate, the more easy to give in. This ismainly because the smaller the loading rate viscous deformation more fully,material yield, the more likely to happen. Through to the material of stressanalysis under different experimental technology to get the yield surface underpressure to cut space, good yield behavior of characterization of the materials.(3) Through the Nano-indenter G200test system for organic glass in thestrain rate of0.01s-1,0.03s-1,0.05s-1,0.1s-1,0.2s-1,0.3s-1and0.5s-1when analysed and studied. And three phase load, load and unload material mechanicsperformance is discussed. Obtained in the loading stage, load and hardness aremonotonically with the increase of strain rate, elastic modulus when the strainrate is lower than0.2s-1has been increased. When confirmed load, materialcreep displacement tends to be stable when its stable value also increases withthe increase of the load and strain rate. Is show the creep loading strain rate onthe displacement of correlation. Mainly because of the high strain rate loading,material in the loading stage accumulates a certain number of viscousdeformation. The deformation will be confirmed carrier phase shift for creepdeformation. In this case loading strain rate, the higher the greater theaccumulation of viscous deformation, the greater the creep deformation. And atthe beginning of the cover load, the higher the greater the strain rate of creepstrain rate. During the unloading phase with the increase of discharge rate,material unloading curve "bulge" phenomenon is more and more is not obvious.