裂解气全分析方法研究

针对目前国内裂解气全分析现状，综合各家所采用的方法，提出了切实可行的裂解气全分析方法，解决了裂解气采样、分析方面的困难。     

裂解气压缩机级间注水技术的应用

介绍了裂解气压缩机由注洗油改为注水情况，进而得出结论：改注水降温效果明显，压缩机工作效能可得到有效保障。     

Repair of notched beam under dynamic load using piezoelectric patch

In this paper, the repair of a cracked beam under an external dynamic load employing the electro-mechanical characteristic of piezoelectric material to induce a local moment is presented. Conceptually, an external voltage is applied to actuate a piezoelectric patch bonded on the beam to effect closure of a crack so that the singularity at the crack tip under dynamic load may be decreased. Globally, this has the effect of altering the resonant frequency of the cracked beam towards that of the healthy beam, which is the criterion used for the repair. To demonstrate the repair methodology, a cantilever beam is used as an illustration, where the repair moment coefficient and the voltage required are mathematically derived. The relationship between repair moment coefficient, crack parameters and length of piezoelectric patch is investigated. The difference between the proposed repair criterion and an earlier published criterion for cracked beam under static load is also shown. A numerical example is used to study the effectiveness of the proposed repair methodology and its results are compared with those from 3-D finite element analyses using ABAQUS 6.4 as one means of verification.     

Cracking induced tribological behavior changes for the HVOF WC-12Co cermet coatings

HVOF sprayed WC based cermet coatings have been widely used in industries as barriers against wear and hydrodynamic cavitation due to their high hardness and relatively high toughness. However, cracking of the coatings can occur during coating production or in service, which can reduce operational performances. It can be difficult to assess the performance impact due to cracks within the coating and as to whether the cracked coatings should be resprayed or removed from service. In this work, artificial cracks of different widths were introduced to liquid fuel HVOF sprayed WC-12Co coating through uniaxial tension of the coated steel substrate to assess the implications of such cracking. Tribological performances of the cracked coatings were examined using rubber wheel dry abrasion, ‘ball on disc’ sliding wear, and ultrasonic cavitation erosion. The results show that the crack deteriorates the abrasive wear resistance of the coating at the initial stage due to preferable mass loss at the cracks. However, after 30?min of abrasion, all the cracked coatings showed the same wear rate as compared to the non-cracked coating, with the abrasive wear resistance acting independent to the crack characteristics. Because the cracks could store wear debris and thus minimize the debris induced abrasion to the coating surface during sliding wear test, both improvement in wear resistance and reduction in coefficient of friction (COF) were detected in the cracked coatings. During the cavitation test, it was found that the mass loss of the specimen increased significantly (up to 75%)with crack width and density suggesting that the crack presence greatly deteriorated the cavitation resistance of the cermet coatings.     

深层—超深层古老烃源岩滞留烃及其裂解气资源评价

我国高-过成熟海相天然气主要成因类型为原油裂解气,滞留烃是原油裂解气的重要来源,对其进行定量研究意义重大。为此,结合正演(实验模拟)和反演(地质剖面解剖)两种方法,求取了我国重点盆地不同类型、不同丰度、不同演化阶段的滞留烃量,建立了5种类型烃源岩(腐泥型、偏腐泥混合型、偏腐殖混合型、腐殖型、煤型)的滞留烃演化模型。结果表明:腐泥型、偏腐泥混合型优质烃源岩在低成熟阶段的排烃效率低于20%,在主生油阶段的排烃效率介于20%~50%,在高成熟阶段的排烃效率介于50%~80%,而相应阶段偏腐殖混合型和腐殖型烃源岩的排烃效率则要低约10%。基于该演化模型,初步计算了四川盆地海相烃源岩中高成熟阶段-现今滞留烃资源分布和裂解排气量:该盆地下寒武统筇竹寺组滞留烃在高演化阶段裂解排出的气态烃总量达230.4×10~(12)m~3,震旦系陡山沱组烃源岩滞留烃裂解气的排出量为12.3×10~(12)m~3,均显示出很好的天然气成藏潜力;进而指出,四川盆地筇竹寺组烃源岩滞留烃裂解气的有利区主要包括高石梯-磨溪、资阳、威远地区,有利分布面积达4.3×10~4 km~2。     

含裂纹故障齿轮系统的非线性动力学研究

考虑时变啮合刚度、间隙非线性及传动误差的影响,针对试验齿轮箱中的单对齿轮传动建立齿轮副扭转振动的参数化动力学模型,对裂纹故障的非线性动力学机理进行研究。采用平均法分析齿轮裂纹模型的主共振及1/2亚谐共振的动力学响应;给出裂纹演化过程对齿轮系统啮合刚度及动力学行为的影响;通过幅频特性曲线、时域图、相轨迹图、Poincaré截面图及频谱图综合分析含有裂纹故障齿轮的振动特征;通过奇异性理论分析裂纹程度及传动误差所产生的内部激励与系统动力学分岔的关系,从而揭示了不同裂纹程度和传动误差所引起的不同分岔模式;最后通过试验提取含有裂纹故障齿轮的振动特征,试验结果验证了理论分析的结果,从而为齿轮系统裂纹故障的识别提供理论依据。     

非线性裂纹转子的分形分析

首先介绍了分形的基本概念,给出了机械振动信号主要应用的分析方法。然后研究了非线性裂纹转子的弯曲振动特性,给出了进入倍周期分叉后裂纹转子的时域特性和频域特性。最后对裂纹转子特性进行分形分析,发现并定义了裂纹转子在进入分叉以前轴心轨迹随裂纹角变化的分形特性,并发现裂纹转子在进入混沌前与进入混沌以后具有相似的分形特性;发现了裂纹转子带噪声信号具有两个分维数（二重分形）的复杂特性。     

裂纹转子识别中Wigner-Ville分布与小波变换的比较

建立基于简单铰链裂纹模型的裂纹转子瞬态响应的动力学模型，得到裂纹转子与无裂纹转子的数值仿真解，比较裂纹转子与无裂纹转子Wigner-Ville分布和小波变换时频特性的不同。数值仿真进一步对比研究Wigner-Ville分布和小波变换对刚度变化的敏感性，并讨论质量偏心和质量偏心角对Wigner-Ville时频特性与小波时频特性的影响，为工程实际中裂纹转子的识别提供依据。     

裂纹梁的相似特性及模型误差分析

固有频率是构造损伤识别指标的常用物理量,它对损伤的敏感性有些低,易受模型误差的干扰。文中应用相似原理,分析得到裂纹梁的动力相似准则,由此找出可引起无量纲固有频率类损伤识别指标变化的相关物理量．有限元仿真结果验证了理论推导的结论。使用这类损伤识别指标的损伤检测方法,在建立精确有限元模型时,可以忽略不影响损伤识别结果的物理量,降低建模难度,实用性强。文中还分析模型误差对无量纲固有频率类损伤识别指标的影响规律。     

CRITICAL STRESS INTENSITY FACTORS FOR CRACKED HOLLOW PIPES UNDER TRANSIENT THERMAL LOADS

Finite element analyses of a long hollow cylinder having an axisymmetric circumferential internal edge crack, subjected to convective cooling on the inner surface are performed. The transient thermal stress intensity factor is estimated using a domain version of the J-integral method. The effect of the thickness of the cylinder, crack length, and heat transfer coefficient on the stress intensity factor history are studied. The variations of critical normalized stress intensity factor with crack length-to-thickness ratio for different parameters are presented. The results show that if a small inner surface crack begins to grow, its stress intensity factor will increase with increase in crack length, reach a maximum, and then begin to drop. Based on the results, a fracture-based design methodology for cracked hollow pipes under transient thermal loads is discussed.