The results indicated that the dimension, shape and purity of base material could meet the functional demand of solid lubricant ; the thermal decomposition temperature of ptfe resin exceeds 400 c, but organic and inorganic packing filler added in ptfe made the water absorption rate of composite material increased, melting temperature and decomposition temperature decreased, in the meanwhile oxidative decomposition reaction was accompanied ; polar groups such as c = o, c - o - c and so on in the carbon fiber surface is advantageous to increase compatibility with other components and interlayer shearing strength ; uniform design experimental method could help to find the relationship between formula and frictional property by relatively small tests. the developing trend of each formula ' s friction coefficient could be showed by fitting curve ; the friction coefficient with no copper powder or graphite in formula was relatively big. this fact showed that copper powder and graphite should be used cooperatively ; it was found that when the ratio of copper powder to graphite by weight is 15 : 60, 30 : 30 - 40 and 60 : 15 - 30 respectively, the friction coefficient was relatively small. the degree of crystallinity of pure ptfe reached maximum by air cooling and the abrasion loss also reached maximum among three ones ; at the same time, the abrasion loss of solid lubricant sample was also the biggest among three ones ; when solid lubricant matched with 45 # steel axle or gcrl5 steel axle, lubricant transfer film could be formed on metal surface, thus direct contact between the surface of metal friction pair rings was reduced. their working life was elongated extremely ; there was mainly much graphite, a little ptff, moo3, feso4, cus and so on in lubricant transfer film
試驗結果表明:所選原料的尺寸、形狀及純度可滿足固體潤滑劑的性能要求;聚四氟乙烯樹脂
熱分解溫度超過400 ,但在ptfe中加入無機填料會使復合材料吸水率提高,熔融溫度及分解溫度降低,且伴有氧化分解反應;碳纖維表面含有c = o及c - o - c等極性基團,有利於提高其與其它組分的相容性,提高層間
剪切強度;均勻設計試驗方法能夠用較少的試驗次數找出配方與摩擦性能間的關系,擬合曲線基本能表示各配方的摩擦系數發展趨勢;配方中不加銅粉或不加石墨,其摩擦系數均較高,說明銅粉和石墨應該配合使用;當銅粉15份、石墨60份時,銅粉30份、石墨30 - 40份時,銅粉60 、石墨15 - 30份時,摩擦系數均具有較低值;純聚四氟乙烯樹脂在空氣冷卻時結晶度最大,磨損量也是三者中最大的;同時,固體潤滑劑試樣在空氣冷卻時的磨損量也是三者中最大的:不論是固體潤滑劑與45 #鋼軸配副或是固體潤滑劑鑲嵌入銅套后與gcr15鋼軸配副,在金屬表面均可形成潤滑轉移膜,從而減少金屬摩擦副表面間的直接接觸,大大延長其使用壽命;轉移膜中主要含有較多的石墨、少量聚四氟乙烯、 moo 。
Hot shears. basic parameters
熱鋼坯
剪斷機.基本參數
The effect of the strain gradient on the onset of adiabatic shear instability in gradient - dependent particle reinforced metal matrix composites is investigated by using of linear perturbation analysis in this paper. the analytical results demonstrate that high strain gradient produced by the reinforcing particle will provide a strong a deriving force for the onset of adiabatic shear instability in mmcp
結果表明:增強顆粒的加入,改變了基體材料的微結構,並在基體中誘導了高的應變梯度,而這種高的應變梯度為mmcp的失穩提供了強大的驅動力,使其更易發生絕
熱剪切變形局部化失穩。
In the beginning, several earnest disciples pitched in to help, but the result was such a disaster that master had to redo the work. the disciples were causing more trouble than rendering help. eventually, we could only watch by the side, at the most serving as assistants, fetching tools like hammers, scissors, and nails
剛開始幾個徒弟還
熱熱鬧鬧的幫忙敲敲打打,結果敲出來的不成樣子,還得勞動師父重做一遍,徒弟簡直是越幫越忙,最後只能在一旁觀摩,最多充當臨時跑腿,配合師父的需要拿工具,例如拿釘子槌子
剪刀等。
Careless use of spiky rollers and hairpins, excessive heat styling and not having the hair trimmed regularly can also cause the problem
不經心地使用銳利的卷發器和發卡過多地進行
熱定型,不經常修
剪頭發都會造成發梢開叉。
Study on microscopic characteristics of adiabatic shear bands in the serrated chips formed during high speed machining
高速切削鋸齒形切屑內絕
熱剪切帶微觀特徵研究
Research was conducted on characteristics of adiabatic shear bands ( asbs ) in several steels by contained exploding cylinder technology
摘要研究了幾種不同硬度和
熱導率的鋼鐵材料在約束爆破條件下的絕
熱剪切帶特徵。
Abstract : a previously proposed approximate quasi - static theoretical method is employed herein to examine the deformation and perforation of a simply - supported circular plate struck by a flat - faced projectile at normal incidence. based on the principle of virtual work, static load - displacement relationships are first obtained and then used to predict the energy - absorbing capacity of the plate subjected to relatively low speed impact. it is shown that good agreement is obtained between the theoretical predictions and the available experimental data, provided that adiabatic shear plugging failure does not occur, but the influence of strain rate sensitivity is taken into account
文摘:採用準靜態近似理論方法分析簡支圓板在平頭彈丸正撞下的變形和穿透.首先基於虛功原理得到了靜態荷載位移關系,並將其用於預測低速沖擊下圓板的能量吸收能力.當考慮了材料的應變率敏感性,並且不發生絕
熱剪切沖塞破壞的前提下,理論預測和實驗結果吻合良好
The effects of reinforcing particle size on deformation strengthening and localization behavior of sicp / 2024al composites are investigated by making use of split hopkinson compression bar and hopkinson torison bar. the experimental results demonstrate that the strengthening effect for the small - size particle - reinforced composite is higher than that for the large - size particle - reinforced composite
實驗表明:這類復合材料無論是在沖擊壓縮還是沖擊扭轉載荷下其變形強化和局部化行為都具有明顯的顆粒尺寸效應,即增強顆粒尺寸越小,變形強化效果越好,越易發生絕
熱剪切變形局部化失穩。
It is recommended for stress caused by vaccination, transport,
減少因預防注射移動高
熱剪嘴引起的緊迫。
In order to describe the adiabatic shearing localization of the projectile that impacts to concrete, the model of adiabatic shearing localization for projectile that impacts to concrete was proposed according to the results of one - dimensional analysis and it was incorporated in the numerical calculations
摘要為描述彈丸材料沖擊混凝土時的絕熱剪切過程,根據沖擊條件下絕熱剪切局部化的一維分析結果,給出沖擊混凝土彈丸材料的絕熱剪切局部化模型並引入到數值分析中。