机电引信串联和并联模型可靠性评估方法

在高价值弹药机电引信研制中,由于产品成本高,不能像常规弹药引信通过大量的试验对产品可靠性进行验证,因此只有通过可靠性评估对产品的可靠性进行确认.针对这个问题,提出了一种高价值弹药机电引信可靠性评估方法,即将机电引信分为电路部分、机构部分和爆炸序列等几大部分分别进行可靠度评估,然后通过串联模型进行综合计算出引信单路子系统的可靠度,最后通过并联模型计算出整个引信的可靠度.通过实践验证,证明了评估方法有效、可行,对以后高价值弹药机电引信可靠性评估的研究具有一定的借鉴意义.     

Enhancement of char‐forming and water resistance on ABS modified by poly(4‐nitrophenoxy)‐phosphazene

Poly(4‐nitrophenoxy)‐phosphazene (DPP) was used as charring and water resistance agent in Acrylonitrile–butadiene–styrene (ABS) composites. The char‐forming capability of DPP and combustion behavior of DPP‐based ABS (ABS‐DPP) were studied by thermogravimetric analysis (TGA) and cone calorimeter, respectively. TGA‐coupled Fourier transform infrared (TGA/FTIR) was used to research the releasing intensity of gaseous products during decomposition. Moreover, the char formation morphology of ABS, DPP, and ABS‐DPP were observed by scanning electron microscopy analysis. The water resistance of DPP was measured by the boiled water tests, the FTIR and static water contact angle analysis. The flame properties of samples and the samples treated by boiled water were studied by LOI and UL‐94, and the tensile properties of ABS‐DPP samples were assessed by tensile testing at high temperature. The results showed that the residues yield of ABS‐DPP samples increased from 0 to more than 20% under nitrogen and from 0.7 to 3.9% under air compared with pure ABS. The combustibility of ABS was decreased by DPP; however, the water resistance of ABS was not affected. At high temperature, tensile strength of ABS‐DPP decreased and the elongation at break enhanced with the addition of DPP. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45988.     

不同水胶比的橡胶混凝土低温力学性能试验研究

在3种水胶比0.35、0.40、0.45下,分别配制含4种橡胶掺量的混凝土,在低温-30 ℃、常温20 ℃和0 ℃进行立方体抗压强度、劈裂抗拉强度试验研究.结果表明,低温条件下,不同水胶比的橡胶混凝土抗压和抗拉强度均有所提高,但强度变化有明显差异,水胶比越大,受低温的影响程度越显著.在0 ℃时,基准混凝土的强度较常温略有下降,随着橡胶掺量的增加,强度由减小转变为增大趋势.低温-30 ℃时,水胶比为0.35时,橡胶混凝土力学性能相对优越.     

外给电子体D-Donor在丙烯聚合中的应用

采用DQ-Ⅳ催化剂,在4L丙烯聚合釜中进行了丙烯聚合实验,考察了外给电子体C-Donor和D-Donor对催化剂活性和聚丙烯（PP）性能的影响。结果表明：采用D-Donor作为外给电子体与C-Donor相比,可使催化剂活性提高20％～30％;PP等规指数提高约1％;结晶温度提高0．833℃,熔点提高2．766℃;相对分子质量略有提高,相对分子质量分布基本未变;拉伸强度提高约13％,弯曲强度提高约26％,缺口冲击强度提高约68％。     

新型脂环环氧树脂/胺体系固化动力学及性能研究

采用DSC研究了脂环环氧树脂稀释剂1,4-环己烷二甲醇二缩水甘油醚(CHDMDGE)与异佛尔酮二胺及聚醚胺D230的固化行为,得出其固化反应的活化能、指前因子和反应级数等动力学参数。通过外推法计算出了固化工艺的特征温度,以此为依据制定了固化工艺并对固化后体系的力学性能进行了测试。结果表明,与线形脂肪族环氧稀释剂1,4-丁二醇二缩水甘油醚和1,6-己二醇二缩水甘油醚相比,CHDMDGE的拉伸强度分别提高了0.4倍和2.7倍,断裂伸长率则提高了1.9倍和5.0倍。     

Influence of Fabrication Residual Thermal Stresses on Rubber-toughened Adhesive Tubular Single Lap Steel-Steel Joints under Tensile Load

The tensile load bearing capability of adhesively-bonded tubular single lap joints which is calculated under the assumption of linear mechanical adhesive properties is usually much less than the experimentally-determined because the majority of the load transfer of adhesively-bonded joints is accomplished by the nonlinear behavior of rubber-toughened epoxy adhesives. Also, as the adhesive thickness increases, the calculated tensile load bearing capability with the linear mechanical adhesive properties increases, while, on the contrary, the experimentally-determined tensile load bearing capability decreases.

In this paper, the stress analysis of adhesively-bonded tubular single lap steel-steel joints under tensile load was performed taking into account the nonlinear mechanical properties and fabrication residual thermal stresses of the adhesive. The nonlinear tensile properties of the adhesive were approximated by an exponential equation which was represented by the initial tensile modulus and ultimate tensile strength of the adhesive.

Using the results of stress analysis, the failure criterion for the adhesively-bonded tubular single lap steel-steel joints under tensile load was developed, which can be used to predict the load-bearing capability of the joint. From the failure criterion, it was found that the fracture of the adhesively-bonded joint was much influenced by the fabrication residual thermal stresses.     

三维整体编织复合材料管的设计与制造

采用四步法编织技术,对三维整体编织管理增强本进行了设计,利用树脂传递模塑工艺成型了复合材料管,并测试了其拉伸性能。     

水可分散型多异氰酸酯的制备与应用

以N-乙烯基吡咯烷酮(VP)、丙烯酸丁酯(BA)、甲基丙烯酸-2-羧乙酯(CA)为单体,通过溶液聚合,制得高分子表面活性剂P(VP-co-BA-co-CA)。以P(VP-co-BA-co-CA)乳化分散1,6-己二异氰酸酯(HDI)三聚体,制得水可分散型HDI三聚体(WD-HDIT),考察了BA质量分数、CA质量分数和HDI三聚体质量分数对乳液粒径和施胶性能的影响。探讨了WD-HDIT乳液对纸张表面的施胶性能。结果表明,当w(VP)=5.0%,w(BA)=3.4%,w(CA)=1.3%,w(HDI三聚体)=60.0%时,施胶剂乳液WD-HDIT具有良好的稳定性和优异的施胶特性。以WD-HDIT质量分数为10%的施胶剂乳液进行表面施胶,纸张施胶度达29 s,纸张与水接触角达119.49°,耐折度达67次,抗张指数达55.8 N?m/g,抗弯挺度指数为2.003 N·m7/kg3,环压强度指数为5.1468 N·m/g。     

一种评估库存发射药安全贮存寿命的方法

为了科学评估库存发射药的安全贮存寿命,通过对库存弹药(发射药)长期贮存试验研究,得到了在库存环境下贮存30多年部分发射药的DPA含量试验数据,建立了相应的数据处理数学模型和安全贮存寿命预测方法。依据试验结果和该数据处理方法,计算出该发射药在置信水平为90％的条件下,安全贮存寿命不低于56年。经试验验证,该评估结果与实际情况基本相符,表明提出的估算库存发射药安全寿命的方法是可以接受的。     

Polymer-grafted cellulose fibers. I. Enhanced water absorbency and tensile strength

To enhance the water absorbency of wood fibers, various acrylic monomers were grafted to these fibers using cerium IV initiation followed by base hydrolysis. The absorbent capacity of hydrolyzed methyl acrylate- or acrylonitrile-grafted wood pulp fibers was an order of magnitude greater than ungrafted pulp fibers. A portion of this enhanced absorbency could be attributed to graft-induced osmotic forces. Enhanced absorbency was relatively independent of wood fiber type. Paper handsheets incorporating 20% grafted fibers had a fivefold increase in absorbent capacity, a twofold increase in dry tensile strength, a threefold or greater increase in wet tensile strength, and were more stretchable. In addition to enhanced absorbent capacity, the rate of absorbency was approximately 50% greater. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65:1463–1469, 1997