共查询到19条相似文献,搜索用时 234 毫秒
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对三种方法修理后复合材料蜂窝夹芯板的侧压性能进行了试验研究,结果表明,不同修理方法均可以有效恢复试件的侧压强度,所有试件侧压强度恢复率均在完好板强度的79%之上.使用k样本Anderson-Darling检验方法对试验结果进行分析,比较固化温度及固化设备等工艺因素对修理后试件力学性能的影响.结果表明:使用中温固化材料完成修理不会对修理结构的力学性能造成明显影响,同时使用热压罐完成修理区域固化通常可以改善修理后试件的力学性能,但改善程度与试件修理区域的有效高度密切相关;此外修理时要尽量避免非对称结构引起的附加弯矩对承载能力造成的不利影响. 相似文献
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为研究工艺因素对含损伤边缘闭合复合材料蜂窝夹芯板胶接修理效果的影响,使用不同工艺参数对含单侧蒙皮损伤和穿透损伤的蜂窝夹芯板进行胶接修理,并对修理后结构的侧压性能进行了试验研究.使用k样本AndersonDarling检验方法对试验结果进行分析,以比较固化温度及固化设备等工艺因素对修理后试件侧压性能的影响.结果表明:两种修理方法均可以有效地恢复试件的侧压强度,所有试件的压缩强度恢复率均达到无损伤板的90%以上;使用中温固化材料完成修理会明显降低结构的侧压性能,同时使用热压罐完成固化可以提升修理后试件的侧压强度,但提升程度十分有限;另外修理时要尽量避免非对称结构对承载能力造成的不利影响. 相似文献
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高温后混凝土与钢筋间的黏结性能影响钢筋混凝土结构的安全评估,实际工程中钢筋混凝土常承受侧向约束作用。为此,该文以高温温度和侧压力为参数,完成了48个钢筋混凝土试件的中心拉拔试验,分析侧压力对高温后试件破坏形态、峰值黏结应力、峰值滑移、残余黏结强度的影响规律,建立了峰值黏结应力随高温温度和侧压力变化的经验公式。将侧压下钢筋-混凝土黏结应力场简化为肋前混凝土挤压力和侧压力的线性叠加,并基于微观传力模型及高温后混凝土的多轴强度破坏准则推导计算了无侧压及单向侧压下的黏结强度理论。研究结果表明:侧压作用和高温温度直接影响试件破坏形态;随着侧压力增加,高温后混凝土与钢筋间的峰值黏结应力、残余黏结强度、峰值滑移逐渐增大,但温度达到500 ℃后,有侧压试件峰值滑移较无侧压试件小;黏结强度理论计算值与实测值较为吻合,能较好地预测高温后混凝土与钢筋间的黏结强度。 相似文献
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制备了复合材料泡沫夹层结构面板缺陷试样,并采用贴补法对缺陷试样进行了修补。通过采用DG-3胶将预先固化好的修补贴片与缺陷区域进行胶接,并采用热补仪将贴补修补后的区域进行加热固化,对贴补修补完成后的试样进行了无损检测、力学性能测试及微观结构分析。结果表明,采用贴补修补后,缺陷直径分别为20mm、30mm试样的拉伸断裂强度分别为0. 644MPa、0. 641MPa,拉伸断裂强度恢复率分别为98. 6%、98. 1%;弯曲强度分别达到2. 186MPa、2. 017MPa,弯曲强度恢复率分别为125. 0%、114. 9%。采用贴补修补法进行修补后,力学性能得到很好的恢复,胶接区域的胶粘剂、修补件与修补贴片间胶接情况良好。 相似文献
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利用混凝土静、动三轴试验系统,完成了粉煤灰陶粒混凝土立方体试件在4组不同冻融循环次数、4种恒定侧压下的双轴压压强度和变形性能试验。考察了不同侧压应力水平下试件的破坏形态和试件表面裂缝分布及走向特征。测量了4种侧压应力水平下的极限抗压强度及两个加载方向的应变值,并根据试验结果系统分析了定侧压下粉煤灰陶粒混凝土双轴压压极限强度和变形性能(包括峰值应变、应力-应变关系曲线、弹性模量)随冻融循环次数和侧压应力水平的变化规律,建立了考虑冻融循环次数和侧压应力水平的主应力空间的双轴压压强度准则,为寒冷海洋环境条件下粉煤灰陶粒混凝土结构在经受双轴压压荷载作用时的强度分析提供试验和理论依据。 相似文献
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胶接修理是效率较高、应用较广的复合材料结构修补技术。对采用不同参数进行挖补和贴补修理的复合材料层合板的拉伸性能进行实验研究。结果表明:挖补修理实验件的强度恢复率约为66%~91%,贴补修理实验件的强度恢复率约为44%~61%。在挖补修理实验件中,减小挖补斜度、采用双面挖补、使用热压罐固化,在贴补修理实验件中,采用双面贴补、增大补片尺寸,均可得到更高的强度恢复率。在实验基础上建立的有限元模型,能够有效预测实验件的失效载荷、破坏模式,并可分析实验件的应力分布和渐进损伤过程,为设计修理方案提供参考。 相似文献
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Sui Liu Zhidong Guan Xia Guo Kai Sun Jiaoyue Kong Dongxiu Yan 《Applied Composite Materials》2014,21(5):689-705
Bonded repairs were conducted on flat and edge-closed composite sandwich panels that had undergone different levels of initial damage, and edgewise compression behaviors of repaired panel were tested. Experimental results indicate that these repair techniques can restore the compression performance of damaged panels effectively. The repaired specimens recovered an average of over 83 % of their strength. A k-sample Anderson-Darling test was used to analyze the influence of various parameters, including curing temperature, curing pressure, and repair configurations. After a thorough comparison, it was concluded that a high-temperature, high-pressure treatment can improve the mechanical performance of repaired panels, but the improvement is closely related to the structural complexity of the repaired region. A double-side repair scheme could be used to prevent the degradation of mechanical performance caused by the additional bending moment. The conclusions drawn in the present study provide further insight into the mechanical performance of repaired sandwich panels under edgewise compressive loads. These data facilitate the improved design methodology on bonded repair of composite sandwich structures. 相似文献
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Francesca da Porto Elena StievaninCarlo Pellegrino 《Cement and Concrete Composites》2012,34(4):545-555
This paper regards the axial behavior of reinforced concrete columns repaired by polymer-modified cementitious mortars. Tests were performed on eight columns with square cross-section: six were repaired with three types of polymer-modified cementitious mortars on all faces, two were in non-damaged and non-repaired condition (control elements). Tests were repeated varying mechanical properties (elastic modulus and compressive strength) of repair materials, maintaining the same repair thickness, including the reinforcement bars. Comparisons between repaired and control elements showed that polymer-modified cementitious mortars cannot restore the original load-bearing capacity of columns. In spite of this, selection of mortar mechanical properties plays a significant role. Among the three types of repair mortar tested in this experimental study, using the material with the most similar elastic modulus and higher compressive strength than that of the concrete substrate is recommended. 相似文献
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目的 研究在逐层交错的方式下,交错角度对瓦楞纸板静态缓冲性能的影响。方法 将单瓦楞纸板以逐层交错的方式粘合,制得0°,30°,45°,60°,90°等5种角度的试样,通过平压试验和侧压试验,研究交错角度对瓦楞纸板承载性能和吸能性能的影响。结果 交错角度对试样的密实化应变影响较小;在侧压试验中,交错角度在0°~45°之间时,试样的侧压强度和比吸能随着角度的增大而减小;交错角度在45°~90°之间时,随着角度的增大,试样的侧压强度和比吸能先增大后减小;在平压试验中,交错角度对试样的平均抗压强度和比吸能影响较小。结论 交错角度对瓦楞纸板侧压缓冲性能影响较大,对平压缓冲性能影响较小。 相似文献
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The results of finite element simulation followed by an experimental study are presented in order to investigate the mechanical behavior of three-dimensional woven glass-fiber sandwich composites using FE method. Experimental load–displacement curves were obtained for flatwise compressive, edgewise compressive, shear, three-point bending and four-point bending loads on the specimens with three different core thicknesses in two principal directions of the sandwich panels, called warp and weft. A 3D finite element model is employed consisting of glass fabric and surrounding epoxy resin matrix in order to predict the mechanical behavior of such complex structures. Comparison between the finite element predictions and experimental data showed good agreement which implies that the FE simulation can be used instead of time-consuming experimental procedures to study the effect of different parameters on mechanical properties of the 3D woven sandwich composites. 相似文献
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Composite structures are very prone to damage at fairly modest levels of impact energy due to foreign object damages. A repair technique using external patch is recognized as an effective method to recover the damaged structures during service life. This work is focusing on the impact damage evaluation and the external patch repair techniques of the aircraft composite structure. The impact damages of composite laminates of the carbon/epoxy UD laminate and the carbon/epoxy fabric face sheets-honeycomb core sandwich laminate are simulated by the drop-weight type impact test equipment. The damaged specimens are repaired using the external patch repair method after removing the damaged area. The compressive strength test and analysis results of the repaired impact damaged specimens are compared with the compressive strength test and analysis results of the undamaged specimens and the impact damaged specimens. Finally, the strength recovery capability after repairing is investigated. 相似文献
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采用四点弯加载方式研究分析了含损伤蜂窝夹层修理结构的弯曲性能,该夹层结构由碳纤维增强的聚合物面板和蜂窝芯子组成。进一步分析了挖补斜度、挖补方式、损伤程度、修理设备和修理材料对修理板弯曲性能的影响。研究表明,修理板的破坏模式可分为补片边缘折断、补片中面折断和胶层破坏三种,相同破坏模式修理板的名义弯曲强度相近,其中前两种破坏模式修理板的名义弯曲强度与完好板相近,而第三种破坏模式修理板的名义弯曲强度相对较低。所有修理板的名义弯曲强度恢复率基本处于95%以上,同时修理后抗弯刚度也满足修理准则。 相似文献
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Adhesive repair of bismaleimide/carbon fiber composites with bisphenol E cyanate ester 总被引:2,自引:0,他引:2
Mahendra ThungaWilber Y. Lio Mufit AkincMichael R. Kessler 《Composites Science and Technology》2011,71(2):239-245
The adhesive strength and repair efficiency of bisphenol E cyanate ester (BECy) is investigated for the injection repair of high temperature polymer-matrix composites (PMCs) by lap shear (LS), short beam shear bending (SBSB), and double-cantilever beam (DCB) tests. Bismaleimide/carbon fiber (BMI-cf) composites were chosen as a model substrate. The BECy resin showed similar strength at room temperature to a benchmark epoxy adhesive and outperformed the epoxy at high temperature (200 °C) in all mechanical tests performed. The influence of moisture content of the PMC substrate on the adhesive strength of BECy was systematically investigated. Drying of PMC before repair was necessary for excellent repair performance. Both the flexural strength of repaired SBSB specimens and the inter-laminar fracture toughness of repaired DCB specimens were significantly higher than that of the control composites and stable over a broad temperature range. 相似文献
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Axial compressive behavior of concrete actively confined by metal strips; part A: experimental study
Hasan Moghaddam Maysam Samadi Kypros Pilakoutas Saiid Mohebbi 《Materials and Structures》2010,43(10):1369-1381
This paper presents the results of an experimental study on the application of strapping technique for retrofit of concrete
compressive specimens. In this technique, standard strapping devices, which are used in the packaging industry, are applied
to post-tension high strength metal strips around the concrete columns. Experimental program included axial compressive tests
on 72 cylindrical and prismatic compressive specimens, which were actively confined by pre-stressed metal strips. The effects
of various parameters on strength and ductility of confined concrete were studied including compressive strength of concrete,
mechanical volumetric ratio of confining strips, post-tensioning force in the strip, number of strip layers wrapped around
the specimens and details of strip joint. The effects of strength and ductility of confining strips on the behavior of confined
specimens were also studied. Longitudinal and lateral strains of concrete and strain of the strips were monitored. Test results
showed significant increase in the strength and ductility of specimens due to active confinement by metal strips. It was observed
that ductility of confining material plays the most important role in enhancement of concrete ductility. The gain in strength
is strongly dependent to the effective mechanical volumetric ratio of confining strips. It was also observed that the active
confinement of concrete by post-tensioning the confining element results in stiffer pre-peak response of concrete specimens
than the usual passive confinement. 相似文献
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Edson C. Botelho Mirabel C. Rezende Sérgio Mayer Herman Voorwald 《Journal of Materials Science》2008,43(9):3166-3172
The continuous use of structural polymer composites in aeronautical industry has required the development of repairing techniques
of damages found in different types of laminates. The most usually adopted procedure to investigate the repair of composite
laminates has been by repairing damages simulated in laminated composite specimens. This work shows the influence of structural
repair technique on mechanical properties of a typical carbon fiber/epoxy laminate used in aerospace industry. When analyzed
by tensile test, the laminates with and without repair present tensile strength values of 670 and 892 MPa, respectively, and
tensile modulus of 53.0 and 67.2 GPa, respectively. By this result, it is possible to observe a decrease of the measured mechanical
properties of the repaired composites. When submitted to fatigue test, it is observed that in loads higher than 250 MPa, this
laminate presents a low life cycle (lower than 400,000 cycles). The fatigue performance of both laminates is comparable, but
the non-repaired laminate presented higher tensile and fatigue resistance when compared with the repaired laminate. 相似文献