On the basis of the research on the main characteristics of rattan materials and the general situations of rattan furniture, this dissertation studied deeply on the quality assesses of rattanfurniture. With the main research object of the rattan furniture, it consisted of three parts—-the quality assesses and test methods of the appearance performances, the mechanical properties of the typical component parts and joints, and the mechanical properties of the holistic products. This systemic, exploratory research provided a basic and technical reference for establishing the standard of assessing rattan furniture quality. At present, this standard has been sent for examining and revising. Simultaneity, the research will also contribute to the more excellent designs of rattan products in the enterprise, and enhance our products’ quality and competitive power in the world.The main research results are as follows:(1) The dissertation analyzed and generalized the basic conditions of the rattan furniture, rattan cane and its derivatives (materials for weave).The moisture content, the axial tensile strength, and mildew resistance of the rattan peel and the rattan core of Calamus simplicfoilius Wei. (one rattan species) have been tested: The rattan peel and the rattan core have approximate moisture contents (between 10%～11%), and they also the fine weaving materials .With the similar sizes, the axial tensile strength of the flat peel is better than the flat core; the axial tensile strength of the peel is better than the flat core; Among the three kinds of the rattan core, the axial tensile strength of the half-round core is the best. The mildew resistance of the weaving surface made of the rattan core is better than the one made of the flat peel.(2) The characteristic of the quality assess of the appearance performances is the research of the quality assess of the layout in weaving surface: The gap margin and distance margin for the close-grid and open-grid surface were referred as the indexes of dimension. The smaller the margins are, the finer the quality of the layout in weaving surface is.(3) The study on the mechanical properties of the typical component parts and joints will provide a good reference for the research of the mechanical properties of the holistic products.1) Weaving surface is a typical component part with good flexibility. In the condition of similar or same size, the flexing resistance of the close-grid one is better than the open-grid one; the flexing resistance of the close-grid one made of the rattan flat peel is better than the one made of the core; the flexing resistance of the weaving surface made by machine is better than the one made by hand.2) T-type and L- type are the typical forms of the rattan furniture joints. The results from the orthogonal tests and the variance analysis have showed that: the connections, the wrapping methods, the wrapping materials, and the species of the rattan cane all have significant effect on the tensile strength and bending strength of T-type joint. Correspondingly, the wrapping materials have smaller effects on the tensile strength, and the species of the rattan cane have smaller effect on the bending strength. Otherwise, the angle-wrapping miter L-type joint has the best bending strength, the bending strengths of the other two forms of L-type joint are relatively poor.(6)A mass of the feasibility tests have showed that: the quality assesses and test methods of the mechanical properties of the holistic products can refer to the corresponding contents in the national standard named “GB/T 10537.1～10537.6 Test of Mechanical Properties of Furniture”. Only the loading times in durability tests need to be modified.
Post about "mechanical property"
Edible film packaging is more and more popular for its convenience and innocuity. It’s a kind of edible and protecting film which can be used as a barrier layer to control water permeability, oxygen permeability, fat oxidation, and volatile flavor loss, hence keeping food in good condition and prolonging food shelf-life. This work focused on edible film based on whey protein concentrate (WPC), studying the film forming procedure, enzyme treatment mechanism and the application properties of whey protein edible film, which is helpful to the further application of edible film.The influences of protein concentration, glycerol concentration, and heating temperature on film formation were studied. The results showed that water vapor permeability (WVP) and oxygen permeability (OP) increased with increase in both protein and glycerol concentrations in the film forming solution. As increasing protein and glycerol concentration elongation increased by 46% and 87% respectively. WVP and OP values reached the lowest when the heating temperature was 70℃. Combined grade of WVP and OP, barrier property was investigated using Response Surface Methods. Mixture proportions of protein concentration 100 g/L, glycerol concentration 27 g/L, heating temperature 69℃, would yield an edible film with WVP 0.435 g·mm/m2·h·kPa and OP 0.134 cm3·mm/m2·d·kPa.Enzymatic treatment showed that, when enzymatic reaction time was 120 min, WVP, OP and film solubility (FS) decreased by 47%, 44% and 13%, respectively, while elongation of film increased by 41%. Enzyme reaction time had no significant effect on tensile strength and film color. As a result, enzyme reaction time fixed at 120 min is advisable for edible film property. When enzyme content was 0.4 g/L, WVP, OP, FS decreased by 48%, 41% and 12%, respectively, while E increased by 56%, and no significant effect on TS and film color were observed. 0.4 g/L was the optimum enzyme amount for film properties.The enzymatic treatment mechanism was investigated. Enzymatic treated protein contained more high weight molecular component according to HPLC result, which induced cross-link between proteins molecular. Denatured temperature of edible film increased according to DSC result. Besides, whey protein hydrophobic property was developed according to fluorescence analysis, while surface–SH content increased, which suggested that protein chains unfolded and hydrophobic group was uncovered, total–SH content decreased suggested that cross-linking promoted forming new S-S bound among protein chains. The SEM picture showed film had a smoother surface. It could be concluded that enzymatic treatment help protein to form more compact structure, all these transformation improve the barrier and mechanical properties of edible film.WPC-coating with and without enzymatic treatment can lower the fat acid value of walnut by 9%~51%, 10%~48%, respectively, and decreased peroxide value by 21%~38% and 22%~43%, respectively. Coating can improve the sensory properties.
As a new kind of environment-protection materials, poly( L-lactic acid ) (PLLA) has a wide application in medicine, industry, national protection, et al, especiallly when it is combined with the technology of electrospinning. But the poor hydrophilicity, low speed of degradation have a bad effect on its application. In this article, poly(vinly alcohol) (PVA) was used to improve PLLA. PLLA/PVA blended or composite micro/nanofibers were prepared by the means of electrospinning. The spinning effect and fibers’properties were analyzed by apparatuses.Firstly, PLLA/PVA composite nanofibers were prepared with the self-assembled electrospinning equipment, in which two kinds of solutions were blended as the spinning solution. The proper technical parameters, which were determined by video zoom microscope and atomic force microscope (AFM), were as follows: 14%/6% of the concentration ratio of PLLA/PVA, 12kV of the spinning voltage, 0.5mL/h of the extruding speed, 18cm of the collecting distance. Well-shaped fibers were obtained with these parameters. Some chemical interaction between PLLA and PVA in the blended fiber had been proved by infrared spectrum (IR) . The incompatibility of PLLA and PVA in the nanofibers was observed using tapping and phase modes of AFM. But there were great differences among nanofibers prepared in different time. More droplets and beads appeared in the latter case. It may be caused by the change of environment and material properties. Because of the unstability of the spinning result, it couldn’t repeated, other preparation method of PLLA/PVA composite nanofibers was taken.A twin-spinneret electrospinning equipment, which had two sets of solution-extruding devices and high-voltage power supplies and a roller as the co-collecting device, was set up and the PLLA/PVA composite micro/nanofibers had been prepared with two kinds of solutions spinning separatedly. After analyzing the images of video zoom microscope and scanning electron microscope (SEM), the most suitable technical parameters were listed as follows: PLLA solution, concentration 30%, voltage 15kV, extruding speed 1.0, 0.8, 0.5, 0.2mL/h, collecting distance 15cm; PVA solution, concentration 10%, voltage 18kV, extruding speed 0.2mL/h, collecting distance 15cm; rotating speed of the roller 200r/min. And the structure, diameter distribution and surface roughness of nanofibers were analyzed by SEM and AFM. The mechanical property of composite nanofiber mats was analyzed by tension test and force-distance curves. PLLA 1.0mL/h showed the best mechanical property and PLLA 0.5mL/h was the worst. PLLA got a better adhesive ability than PVA did. Composite nanofiber mats had a great improvement on the wettability comparing with the pure PLLA nanofiber mat, which was proved by the tests of static contact angle and dynamic water adsorption. PLLA 0.2mL/h was the best. Some improvements on the thermal stability of PLLA had been made with PVA added.
High strength low carbon bainitic steel WDB620 is a kind of steels which is a new generation high-strength steel of low susceptibility to welding crack made in China, the performance fully meet the large steel structure on the low susceptibility to welding crack the requirement. It can substitute with the import CF62 steel and has been used extensively in pressure Hydropower pressure containers such as steel pipe structure. WDB620 were used in the Wa Wushan Hydropower Station’s penstock at large, but we found some impact energy unsteady and less than the relevant specifications and design requirements in the mechanical properties testing of the steel and welded joints. This has led to rejecting the bifurcation which was assembled to be welded , Causing heavy economic losses.This paper studies on the mechanical properties and microstructure of high strength low carbon bainitic steel WDB620 and welded joints. Through micro-shear test of the 62 mm thick WDB620 especially Z direction and multi-passes welding joints ,the paper make gradient performance curve of WDB620 and welding joints in different depth. And through optical metallographic microscope ,this paper analyze of the microstructure differences of the steel and welding joint ,find out the reasons for mechanical properties instability. Some significant recommendations to ensure the plate microstructure and mechanical properties uniform was given.This paper also collect together the high strength low carbon bainitic steel’s micro-shear test’s shear energy and the impact energy data of impact test ,use probability and mathematical statistics method, obtain the curve regression experienced formula.
The Influence of Procession Technology and Welding Craftwork on Organization and Performance for the Rectangle Pipe
With the development of the roll formed shape,the roll formed shape assembly is widely used in many projects. From airports to major shopping centers, form offices to stadiums, from conference centres to housings, many of the building materials make use of them. With the appearance of the large-caliber bend square and rectangular pipe, the place of this kind of pipes is more and more important.Due to the complexity of the cold bending processing, the mechanical property and structure property is difficult to control. So we often improve technological parameters after the examination of the finished goods to meet the needs. For the sealing, the toughness of the pipes reduces, and with the crackle of the weld, the product percent of pass is too low.To improve the product percent of pass, the experiments base on the filed tests and lab tests. By the tests, finding out the influences of the procession technology and welding craftwork on organization and performances for the rectangle pipe. On the experiments at the molding process, the products’are 250*250*9.2 and 200*300*9.2 ,Q345B; at the welding process, the products’are 250*250*9.75 and 200*300*11.8 ,Q235B The molding process is 15 steps, and the welding procedure is high frequency welding. By all the tests, we find out a suitable technics: V-angle is 4°-6.13°, the power of the side is 0.35～0.4KJ/mm~2;V-angle is2°-4°,the power of the side is 0.2～0.22KJ/mm~2.
In this paper,nylon6(PA6) composites which filled with short glass fiber(GF) and different granulated SiC are prepared by the extrusion and injection moulding process.The mechanical properties and tribological properties of composites are evaluated on CSS-44100 electronic universal tester and M-2000 friction and wear tester respectively,and the tensile fracted section and wear surface of the composites are observed by scanning electron microscopy(SEM) and thus analyzing the synergies mechanism of GF and SiC.The mechanical properties of PA6 composites are investigated and the results indicate that:The tensile strength,flexural strength,flexural modulus and hardness of PA6 composite enhance greatly,but the tensile elongation decreases because of the filling of GF immingled with SiC.This kind of composite possesses better general mechanical properties because of two fillers having good synergical reinforced effect,which nano-SiC has better improvement than that of micro-SiC,and the composite filled with 10wt%has better properties than that of 20wt%.All these together mainly attributable to the granularity of filled particles,and that dispersion in the matrix,as well as the link situation between the resin and filler.In this proposed experimental condition,excellent mechanical properties can be reached for PA6 composite with 10%nano-SiC and 10%GF.SEM analysis shows that: GF combines close with the resin because of SiC connecting role,and nano-SiC and GF act as bearing of stress,thus increase the intensity of the composite,but lower toughness acting more “toughness nests” on the tensile section.At the same time,the tribological behaviours of PA6 composites filled with different fillers under different load are studied,and the results show that:The wear mass loss increases along with the accretion of the load,but the friction coefficient has different changing rule.And the composite filled with GF and SiC has better property,even nano-SiC has much better modification.The excellent property constitution as follows:when GF content is 10%in the composite,that of nano-SiC is 3%and when GF content is 20%,that of nano-SiC is 9%,and the latter has better tribological behaviours.The morphology analysis showes that 20%GF and 9%nano-SiC can combine close with PA6 resin,this composite can form stable transfer film during wear and its wear mechanism is abrasive wear under lower load while that of adhesive wear under higher load.
Along with the fast development of the transportation industry, the equipments also turn to the direction of large-scale, high speed, the heavy load, and the high security. So the standard of the operational-performance of the friction material is being set more and more higher. Recently, researchers are turning their attention to a new type of composite material-interpenetrating phase composites. This combination gives full play to the advantages of both the reinforced phase and the matrix phase by interpenetrating and mutual supporting, therefore brings the outstanding physical, chemical and mechanical performance.Leading Cu into the SiC carcase to produce the 3D-Meshy SiC/Cu composite material. Some researches of this material on the mechanical property, the interface reaction, the influence of heat treatment and the friction and wear property were did. The results are as follows:(1) Bending strength of the 3D-Meshy SiC/Cu composite material reached 225.9MPa, compression strength reached 199.9MPa, and tensile strength to 19MPa. Interpenetration of the SiC reinforced phase and the Cu matrix phase resulting the mutual supporting when the load is added, so the mechanical property improved a lot.(2) Interface reaction existed during the casting procedure of the 3D-Meshy SiC/Cu composite material. The interface reaction mainly divides into three steps:(1) SiC decomposed into Si and C; (2) SiC and C produced by the SiC reacted with the Cu matrix, resulted variety interface products; (3) solid phase diffusion. The main interface products include Cu4Si、C、TiC、V-C、Cr-C and Cr-Si compound. There are mainly four interface reaction region from the SiC framework to Cu matrix:the first region include Cu4Si、C、Ti-C and Cr-C compounds; The second region is the transition zone of the first and third region; The third region mainly are TiC and V-C, and the fourth is Cr-Si compounds; The third and fourth regions are at the forefront of the interface reaction region, which blocked the atoms diffusion of the two sides of interface, and restrained the interface reaction.(3) After the 3D-Meshy SiC/Cu composite material was heated at 700℃and held for 30、60、90、120min, no new interface compounds or phases were detected. The heat treatment made no big influence to the other element’s distribution of the interface region,except changing C’s distribution in the first region, as the increase of the heat treatment time, large-scale graphite phase began to disappear and turned to dispersely distributed particles; Cu has oxidized gradually into Cu2O and CuO during the heat treatment process; After the heat treatment, the Cu substrate’s grain size increased, and the density of the twin crystal also increased; show The diffusion coefficient D of Cu was 2.76×10-14 m2·s-1 calculated through the Fick diffuse law. (4) Simulation of braking experiment on passenger vehicle has been carried out by using the 3D-Meshy SiC/Cu as Static ring and cast iron as moving ring. The results showed that: with the increase of the rotational speed, the average friction coefficient and acceleration reduced while the braeking time and braking distance increased. with the increase of the pressure, the average friction coefficient、braking time and braking distance all reduced while the acceleration increased; The abrasion mechanism in the braking process mainly is abrasive wear, while follwing with some additive wear, and, the material transport from cast iron ring to 3D-Meshy SiC/Cu ring occured. The 3D-Meshy SiC was able to support the load applied onto the sliding surface and restricted the plastic deformation and high-temperature softering of the Cu matrix, thus it showed nice friction and wear properties.
With the enhancement of protecting the environment consciousness, the LNG (Liquefied Natural Gas) is used more and more because of being a variety of clean energy. Consequently, it is a critical thing to develop 9Ni constructional material with self-owned intellectual property rights. The mechanical property of 9Ni steel was focused. And the influence of each process on the microstructure and mechanical property was investigated by means of component design, thermal simulation, rolling process and heat treatment process. Moreover, parameters optimization was achieved. The main experiments and conclusions were as follows:1. Referred to domestic and overseas standards of 9Ni steel, effective component scheme was provided though optimizing component parameters.2. The hyperthermia deformation experiments were done by use of the thermal simulation machine. The relationship of austenitic stress-strain under different temperatures and speeds was established by single-pass compression experiment. In addition, model of the resistance to deformation was deduced. And the static and dynamic CCT curves of 9Ni steel were drawn by continuous cooling transformation experiment. The conclusions were as follows:there are only bainite transformation zone. Compared with static CCT curve, the temperature of bainitic starting transformation is lower, conversely its finishing transformation is higher. So it means that the speed of dynamic bainite transformation is higher.3. The die-casting and continuous casting-rolling process were repeated. In order to get 4R(Reduce, Reuse, Recycle, Remanufacture) target, rolling process of finishing temperature at two-phase region and heat treatment online was tried. And mechanical properties of 9Ni steel under both processes were excellent.4. The influences of component of 9Ni steel and finishing rolling temperature on mechanical property were analyzed. The conclusions were as follows:the content of nickel is significant to its mechanical property. Neither lower nor higher of the nickel content is benefit to its mechanical property. Additionally, the microstructure is fine when the finishing rolling temperature is 730℃. 5. The parameters of heat treatment processes were optimized by changing the temperature parameters in every stage. Moreover, the relationship among temperature, microstructure and hypothermia impact toughness was studied. The conclusions were as follows:in the process of quenching and tempering (QT) heat treatment, the optimized temperature parameters are quenching at 800℃and tempering at 580℃. Additionally, the temperature of quenching has a great effect upon grain size, and the temperature of tempering has a great influence on the precipitation and stabilization of reverted austenite. Then in the process of quenching, intermediate quenching and tempering (QLT) heat treatment, the optimized temperature parameters are quenching at 800℃, intermediate quenching at 670℃and tempering at 580℃. But the temperature of quenching has no obvious influence in QLT heat treatment. Similarly, the temperature of tempering has the same effect. Compared two heat treatment process, the hypothermia impact toughness of 9Ni steel is improved by the QLT heat treatment.
Study on the Welding Technology and Forming Performance of Multi-gauge High Strength Steel Laser Tailor-welded Blanks
Having largely improved body light weight process in vehicle manufacture, multi-gauge high strength steel laser tailor-welded blanks compliance to the continue development today and must be regarded by lots of auto manufacturers.Since the difficulty existed in the welding of multi-gauge high strength steel laser tailor-welded blanks, welding quality will directly affect the mechanical property. It is very important to study the effect of welding parameter to multi-gauge high strength steel laser tailor-welded blanks.This study used the analyzing of microstructure in welding seam and HAZ as foundation, discussed internal rule among the welding parameters, microstructure and welding specimen mechanical property. It will provide the direction for practice applying.In the second chapter, parameterized Steen W M’s heat source model of superposition with point heat source and line heat source by generating function and transferring coordinate, introduced it into studying of multi-gauge high strength steel laser tailor-welded blanks. Theoretic outline of welding seam obtained by the model consistent well to the one got from experiment. We also calculated thermal cycling curve by the mathematics model.In the third chapter, laser welding experiment of multi-gauge high strength steel laser tailor-welded blanks was finished. We only spent very few tries of parameter debugging and obtained correct practical welding parameter with the guiding of the theoretic parameter deduced from second chapter. It avoids the blinding in welding parameter design.In the forth chapter, we discussed effect regularity of different welding power, welding speed, welding heat input to the microstructure and microhardness of welding specimen with longitudinal weld seam. Result indicated (1) width of HAZ will changed by different laser welding power and laser welding speed. (2)the amount of granular bainite and cementite will be changed by different welding power. (3) welding speed affected a lot to the precipitation amount and shape of grain boundary ferrite. (4)grain increase trend in HAZ affected by laser heat input, and use lower heat input can control the increasing trend.In the fifth chapter, we used tensile test to study the specimen mechanical property with different welding parameters. We also studied effect of different welding parameters to mechanical property by the microstructure result in chapter four. The result showed: (1)increase the welding speed appropriately can enhance the plastic nature and ductility of welding specimen if the welding quality is eligible. (2) welding specimen with larger power have lower plastic nature. (3)the true stress-strain curve will advanced by the increase of heat input. It indicated that the plastic ability will be reduced by the increasing of heat input.
UV curable polysiloxanes materials possess the advantageous properties of polysioxanes and UV curing technique, such as high efficiency and low energy consumption. UV curable prepolymers of polysiloxane could usually be classified as polysiloxanes bearing acrylic or thiol/vinyl groups in photoinitiated radical polymerization, and other ones with epoxy or vinyl ether group undergoing photoinitiated cationic polymerization. Polysiloxanes bearing acrylic groups display extraordinarily high reactivity, ultimate properties, low cost, especially attractive for applications as electronic and decorative coatings, adhesives, and inks.Firstly, a range of pre-polymers of polysiloxane with different content of acrylic group were synthesized, by the esterification reaction of acrylic acid with alkyl-hydroxyl-contained silicone oil. The influences of the amount and kind of catalysts and inhibitors, reaction temperature, reaction time on the conversion were investigated, to achieve the optimal experiment conditions. The structures of the product under optimal reaction condition were characterized by FTIR and NMR.Secondly, at the present of photoinitiators, the prepolymers of polysiloxane with different content of acrylic groups, were polymerized under UV radiation. Properties of UV-cured materials were measured, including mechanical properties, index of refraction, volume contraction, and crosslink densities of corresponding cured polysiloxanes, were measured by the mechanical method. Finally, we investigate the influences of crosslink densities on mechanical properties, refractive index, rate of volume contraction.Finally, the synthesis of silylated photoinitiators incorporated the group of photoinitiator into the main chain of Si-O, were synthesized by dehydrogenation reaction of hydroxyl-contained photoinitiator with hydrogen-contained polysiloxanes. The photosensitive property of the silylated photoinitiator were investigated.The study focused on UV-curable polysiloxane about the synthesis, UV-curing of prepolymer with different content acrylic groups, and the synthesis of silylated photoinitiator. The results of the paper would be useful and significative to study and to overcome the shortcomings and limits of UV-curable materials in application.