Dynamic and electrical responses of a curved sandwich beam with glass reinforced laminate layers and a pliable core in the presence of a piezoelectric layer under low-velocity impact

The dynamic responses and generated voltage in a curved sandwich beam with glass reinforced laminate(GRL)layers and a pliable core in the presence of a piezoelectric layer under low-velocity impact(LVI)are investigated.The current study aims to carry out a dynamic analysis on the sandwich beam when the impactor hits the top face sheet with an initial velocity.For the layer analysis,the high-order shear deformation theory(HSDT)and Frostig's second model for the displacement fields of the core layer are used.The classical non-adhesive elastic contact theory and Hunter's principle are used to calculate the dynamic responses in terms of time.In order to validate the analytical method,the outcomes of the current investigation are compared with those gained by the experimental tests carried out by other researchers for a rectangular composite plate subject to the LVI.Finite element(FE)simulations are conducted by means of the ABAQUS software.The effects of the parameters such as foam modulus,layer material,fiber angle,impactor mass,and its velocity on the generated voltage are reviewed.

Low velocity impact studies of E-glass/epoxy composite laminates at different thicknesses and temperatures

Low velocity impact experiments were carried out on E-glass/epoxy composite laminates having varying thicknesses at sub zero and elevated temperatures using hemi spherical steel impactor of 16 mm diameter with impact energies in the rage of 50-150 J.The performance of the laminates was assessed in terms of energy absorption,maximum displacement,peak force and failure behaviour.Results indicated that the effect of temperature on energy absorption of the laminate is negligible although the laminates are embrittling at sub zero temperatures.However it has influence on failure behaviour and displacement.Peak force has increased linearly with increase in laminate thickness from 5 to 10 mm.However it got reduced by 25% when temperature was increased from-20℃ to 100℃,Based on experimental results,laminate perforation energies were predicted using curve fitting equations.Statistical analysis was carried out using Taguchi method to identify the global effects of various parameters on laminate performance and confirmed that the laminate thickness has significant influence as compared to temperature,for the studied range.

Experimental and simulation studies on delamination strength of laminated glass composites having polyvinyl butyral and ethyl vinyl acetate inter-layers of different critical thicknesses

The laminated glasses(LGs)composites are gaining popularity as protectivestructural material. Delamination strength(DS) of(LGs) with different inter-layers and their different nominal thicknesses were compared. The effect of inter-layer thickness, delamination load, and inter-layer type on DS is clearly observed from this brief study. It is concluded that inter-layer thickness has the significant role in determining the DS of LGs. The statistical analysis confirmed the strong association of DS with inter-layer thickness and the interlayer type. It was found that the LG-PVB composite has the comparatively lower DS than LG-EVA composite and inter-layer thickness has the prominent role in the determination of DS in the LG-EVAcomposite. There is an increment in DS with an increment in critical inter-layer thickness in both LG-EVA and LG-PVBcomposites. The increment in the inter-layer thickness from 0.38 mm to 0.76 mm increases DS significantly; whereas, the further increment in the inter-layer thickness to the higher value has a lesser effect. The finite element model was constituted(without considering the effect of temperature) for determining DS of LG composite. The simulation results were in a good match with experimental results. The results of the present work can be utilized by the design engineers while selecting LG for structural applications.

The Effect of Glass Plate Thickness and Type and Thickness of the Bonding Interlayer on the Mechanical Behavior of Laminated Glass

In this work the effect of the type of the bonding interlayer (polyvinyl butyral (PVB) or Ethyl Vinyl Acetate (EVA)), number of bonding layers, and the position and the thickness of the Glass plates on the maximum load capacity and absorbed energy by laminated glass. Furthermore, this investigation presents a mathematical model that relates the maximum force capacity of the glass laminated structure to the glass plate thickness, type and thickness of the inter-layer regardless the position of the fixed glass plate. Both practical work results and the theoretical model indicate that the maximum load capacity of laminated glass bonded with either PVB or EVA decreases as the interlayer thickness increases. Moreover, the maximum load capacity for the glasses bonded with EVA is greater than those for the PVB bonded ones under the same conditions. On the other hand, it was observed that that laminated glass absorbed energy increases with the increase of the interlayer thickness and the increase of glass plate thickness.

Damage visualization and deformation measurement in glass laminates during projectile penetration

Transparent armor consists of glass-polymer laminates in most cases.The formation and propagation of damage in the different glass layers has a strong influence on the ballistic resistance of such laminates.In order to clarify(he course of events during projectile penetration,an experimental technique was developed,which allows visualizing the onset and propagation of damage in each single layer of the laminate.A telecentric objective lens was used together with a microsecond video camera that allows recording 100 frames at a maximum rate of 1 MHz in a backlit photography set-up.With this technique,the damage evolution could be visualized in glass laminates consisting of four glass layers with lateral dimensions 500 mm x 500 mm.Damage evolution was recorded during penetration of 7.62 mm AP projectiles with tungsten carbide core and a total mass of 1 1.1 g in the impact velocity range from 800 to 880 m/s.In order to measure the deformation of single glass plates within the laminates,a piece of reflecting tape was attached to the corresponding glass plate,and photonic Doppler velocimetry(PDV) was applied.With the photonic Doppler velocimeter.an infrared laser is used to illuminate an object to be measured and the Doppler-shifted light is superimposed to a reference light beam at the detector.The simultaneous visualization and PDV measurement of the glass deformation allow determining the deformation at the time of the onset of fracture.The analysis of the experimental data was supported by numerical simulations,using the AUTODYN commercial hydro-code.

Mechanical Properties of Thermoplastic Polyurethanes Laminated Glass Treated by Acid Etching Combined with Cold Plasma

To overcome the problem of interlaminar delamination of thermoplastic polyurethane laminated glass, silicate glass was etched with hydrofluoric acid and thermoplastic polyurethane was then treated with cold plasma. Compared with the untreated samples, the interlaminar shear strength of acid etching samples, cold plasma-treated samples and acid etching combined with cold plasma-treated samples increased by 97%, 84% and 341%, respectively. Acid etching combined with cold plasma-treated samples exhibited a higher flexural strength and strain as compared with the untreated samples. The impact energy of acid etching samples, cold plasmatreated samples and acid etching combined with cold plasma-treated samples increased by 8.7%, 8.1% and 11.6%, respectively, in comparison with the untreated samples. FT-IR analysis showed that a large number of -C-O, CO N and CO O C groups appeared on the surface of cold plasma-treated thermoplastic polyurethane, which resulted in the formation of hydrogen bonds. SEM results showed that some pittings formed on the surface of the silicate glass treated by acid etching, which resulted in the formation of a three-dimensional interface structure between tile silicate glass and polyurethane. Hydrogen bonds combined with the three-dimensional interface between silicate glass and polyurethanes co-improved the mechanical properties of thermoplastic polyurethanes laminated glass.

CONSTITUTIVE MODEL AND DYNAMIC MECHANICAL PROPERTIES OF GLASS-CLOTH/EPOXY LAMINATES AT DIFFERENT TEMPERATURES

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Interlaminar Fracture Toughness of Epoxy Glass Fiber Fly Ash Laminate Composite

Epoxy glass fiber laminate composite (PMCs) are finding ever increasing applications in aerospace and automobile industries due to its high strength to weight ratio and resistance to aqueous environment. Additions of particulate reinforcements in the polymer matrix are reported to improve the Interlaminar Shear Strength and Interlaminar Fracture Toughness of the composites. In the present investigation, epoxy glass fiber laminate composites were processed using hand layup and vacuum bagging technique. The particulate reinforcement precipitator fly ash (25 - 45 μm) was added in the epoxy matrix by mechanical mixing up to 10 wt%. The effects of fly ash reinforcement on the mechanical properties and Interlaminar Fracture Toughness were studied before and after exposure to aqueous fog in a salt fog chamber at 45°C. In unexposed condition Mode I interlaminar fracture toughness of epoxy glass fiber laminate composite improved by the addition of fly ash reinforcement 10% (By weight) by 49.43% and when it was subjected to aqueous fog for 10 days the interlaminar fracture toughness improved 58.42%. Exposure to aqueous fog for 10 days causes plasticization of resin matrix and weakening of fiber/matrix interface results in improvement in interlaminar fracture toughness. The fracture surfaces were analyzed using scanning electron microscopy.

Experimental Vibration Analysis of a Cracked Laminated Glass Beam with Bolted Joint

In this study, in order to determine the very early load transfer behavior in the bolted joint connection, experimental dynamic analysis of different laminated glass beams including two surface cracks is considered. For this purpose, both three different plastic interlayers （i.e., three types of polyvinyl butyral--PVB） and three different glass-lamina thicknesses are taken into account. Effects of the plastic interlayer, thickness of the glass-lamina, number of surface cracks and their locations on the vibration characteristics/structural performances are examined experimentally. Vibration tests are performed to present free vibration characteristics of the laminated glass beams under clamped-free boundary conditions. Experimental dynamic analysis consists of six parts： （I） vibration analysis with no-crack and no-hole with a bolted joint; （I1） vibration analysis with a surface crack and no-hole with a bolted joint; （III） vibration analysis with two surface cracks and no-hole with a bolted joint; （IV） vibration analysis with no-crack and a hole with a bolted joint; （V） vibration analysis with a surface crack and a hole with a bolted joint; （VI） vibration analysis with two surface cracks and a hole with a bolted joint. For these experimental steps, an impact hammer with a force transducer is used to excite the uncracked or cracked composite beams through the selected points. After the excitation, the responses are obtained by an accelerometer. The vibration measurements are completed using a microprocessor-based data acquisition system and nCode GlyphWorks software. Results are given in tabular and graphical forms.

A FATIGUE FAILURE CRITERION OF NOTCHED GFRP LAMINATES

A fatigue failure criterion for predicting the fatigue life of notched orthotropic fiber reinforced plasties (FRP) plates based on the concept of stress field intensity (SFI) near the notch root is subjected to further experiments. The investigation is accomplished by obtaining experimental data on the notched specimens of glass fiber reinforced plastics (GFRP) with edged notches under tension tension cyclic loading. The process of initiation and growth of fatigue damage near the notch root is measured by means of the optic system with a computer controlled display (CCD) camera. The experimental results show that the number of loading cycles required to initiate fatigue damage is governed by the stress field intensity.

Progress on the glassy-crystal laminates:From design,microstructure to deformation and future solutions

The development of new design strategies to create innovative structural materials,refine existing ones,and achieves compatible combinations of strength and plasticity remains a worldwide goal.Promising alloys,such as shape memory alloys(SMAs),bulk metallic glasses(BMGs),high entropy alloys(HEAs),and heterogeneous pure metals such as Cu,have excellent mechanical responses,but they still fall short of meeting all the requirements of structural materials due to specific flaws,such as lack of tensile de-formation for BMGs and low yielding strength for HEAs.To address these shortcomings,proposals such as integrating glassy matrices and crystallized alloys,such as HEAs/SMAs,have been suggested.However,these solutions have unresolved issues,such as the challenging control of B2 phase formation in BMG composites.Recently,glass-crystal(A/C)laminated alloys with alternating layers have been reported to exhibit improved mechanical properties and activated work-hardening behaviors,but they still face press-ing issues such as bonding interfaces and unknown deformation mechanisms.This review focuses on design routes such as the selection of alloy components and processing techniques,exploration of micro-structural evolution and deformation modes with an increase in strain,and future solutions to address pressing and unsolved issues.These prominent advantages include diversified deformation mechanisms,such as deformation twinning,martensitic phase transformation,and precipitation hardening,as well as tuned interactive reactions of shear bands(SBs)near the A/C interfaces.Thus,this review provides a promising pathway to design and develop structural materials in the materials field community.

Mechanical Properties of Lab Joint Composite Structure of Glass Fiber Reinforced Polymers

Glass fiber composite laminates have competitive properties than monotonic material for their superior mechanical strength. Lab joints in composite structure are of great importance in aerospace and aircraft industry. Therefore, lab joints’ strength and failure of composite laminates structure are experimentally investigated. Composites laminates of four different stacking sequences and layup are manufactured using hand layup technique and curing at room temperature. Specimens of unidirectional laminates of [0]8 stacking sequence are used to test lamina mechanical properties while [0/90]2s, [0/60/90]s and woven are used to test the mechanical properties of lab joints. Lab joints of single row and double row are produced and tested in bearing using simple mode I test (tension test). The results illustrate that bearing strength of quasi-brittle laminates of [0/60/90]s has more stability and strength than that of woven glass fiber, then the cross ply laminates of [0/90]2s;this can be attributed to increase of anisotropy of cross ply laminates than other composite laminate structure.

建筑夹层玻璃风致飞射物冲击破坏易损性研究

为分析建筑夹层玻璃遭受风致飞射物冲击时的破坏特征和机理,定量评价其易损性,采用有限元方法开展冲击破坏数值模拟研究。基于LS-DYNA软件建立飞射物冲击夹层玻璃的有限元模型,通过有限元数值模拟与试验对比验证有限元数值模拟方法的可靠性;分析球状飞射物冲击夹层玻璃时的裂纹开展和应力传播特征;改变球状飞射物的冲击位置、半径大小、材质和夹层玻璃面板长宽比,研究飞射物对夹层玻璃冲击效应的影响;采用双参数Weibull分布建立夹层玻璃冲击失效概率计算,量化其易损性。结果表明:与夹层玻璃中部和边部相比,角部抗冲击性能差;相同冲击速度下,夹层玻璃冲击失效概率随着飞射物半径的增加而增大;与石球和木球相比,钢球对夹层玻璃破坏临界速度低;当面板面积恒定时,随着长宽比的增加,其冲击失效概率先减小后增大。

折叠式手机玻璃的现状及发展

从直板机到折叠式机,随着手机的更新换代,推动了手机玻璃的发展。为适应折叠式手机要求,手机玻璃盖板必须具有柔性、韧性,可以弯曲折叠20~25万次,相当每天500次而不破裂,为此可选用叠层复合材料。叠层复合材料是由UTG超薄玻璃和CPI聚酰亚胺类型高分子材料保护膜通过热熔胶或热压贴合工艺形成的增强材料,利用UTG的刚性和CPI的塑性组合成韧性的叠层复合材料,从而提高折叠式手机玻璃盖板的抗冲击能力,将是今后手机玻璃的发展方向。

碳/玻混杂纤维铺层顺序对其复合材料力学性能的影响

混杂纤维增强复合材料可通过混杂纤维的协调匹配产生协同混杂效应,从而提高复合材料在强度、刚度、性价比等方面的优势。为了研究碳纤维与玻璃纤维铺层顺序对复合材料力学性能的影响,制备5种不同铺层顺序的碳/玻混杂纤维增强复合材料,结合显微组织与拉伸断口分析了纤维铺层顺序对其强度、刚度、应力-应变曲线的影响规律。结果表明:铺层顺序对复合材料的力学性能影响显著,铺层间隔越均匀其增强效果越好,碳纤维或玻璃纤维集中分布于试样中间时均不利于复合材料性能的提升,碳纤维、玻璃纤维单层间隔时其抗拉强度比纯玻璃纤维增强复合材料提高了约60%,3层间隔时其强度略低于纯玻璃纤维增强复合材料;铺层间隔越均匀其层间开裂越集中且断口处纤维单丝拔出长度越大;碳纤维加入后复合材料的刚度大幅度提升,其应力-应曲线出现不同程度的波动,但铺层顺序对复合材料刚度影响甚微。

New ductile laminate structure of Ti-alloy/Ti-based metallic glass composite with high specific strength

Bulk laminate structure of Ti-alloy/Ti-based metallic glass composite （MGC） was prepared by melting a preform of alternate stack-up foils in the high vacuum atmosphere. The composite demonstrates a good combination of yield strength （-1618MPa）, plasticity （-4.3%） and specific fracture strength （384 × 10^3 N m kg^-1 ） in compression. The maintained yield strength results from the unique microstruc- ture composed of the Ti layer, the solution layer with gradient structure and the MGC layer. Such a multilayer structure effectively inhibits the propagation of shear band, leading to the enhanced plastic- ity. Those extraordinary properities suggest that combining ductile lamella with brittle metallic glass （MG） by such a lay-up method can be an effective way to improve mechanical properties of MG.

Improvement of thermal conductivities and simulation model for glass fabrics reinforced epoxy laminated composites via introducing hetero-structured BNN-30@BNNS fillers

Hetero-structured thermally conductive spherical boron nitride and boron nitride nanosheets(BNN-30@BNNS)fillers were prepared via electro static self-assembly method.And the corresponding thermally conductive&electrically insulating BNN-30@BNNS/Si-GFs/E-44 laminated composites were then fabricated via hot compression.BNN-30@BNNS-Ⅲ(fBNN-30/fBNNS,1/2,wt/wt)fillers presented the optimal synergistic improvement effects on the thermal conductivities of epoxy composites.When the mass fraction of BNN-30@BNNS-Ⅲwas 15 wt%,λvalue of the BNN-30@BNNS-Ⅲ/E-44 composites was up to0.61 W m^(-1)K^(-1),increased by 2.8 times compared with pure E-44(λ=0.22 W m^(-1)K^(-1)),also higher than that of the 15 wt%BNN-30/E-44(0.56 W m^(-1)K^(-1)),15 wt%BNNS/E-44(0.42 W m^(-1)K^(-1)),and 15 wt%(BNN-30/BNNS)/E-44(direct blending BNN-30/BNNS hybrid fillers,1/2,wt/wt,0.49 W m^(-1)K^(-1))composites.Theλin-plane(λ//)andλcross-plane(λ_(⊥))of 15 wt%BNN-30@BNNS-Ⅲ/Si-GFs/E-44 laminated composites significantly reached 2.75 W m^(-1)K^(-1)and 1.32 W m^(-1)K^(-1),186.5%and 187.0%higher than those of Si-GFs/E-44 laminated composites(λ//=0.96 W m^(-1)K^(-1)andλ_(⊥)=0.46 W m^(-1)K^(-1)).Established models can well simulate heat transfer efficiency in the BNN-30@BNNS-Ⅲ/Si-GFs/E-44 laminated composites.Under the condition of point heat source,the introduction of BNN-30@BNNS-Ⅲfillers were conducive to accelerating heat flow trans fe r.BNN-30@BNNS-Ⅲ/Si-GFs/E-44 laminated composites also demonstrated outstanding electrical insulating properties(cross-plane withstanding voltage,breakdown strength,surface&volume resistivity of 51.3 kV,23.8 kV mm^(-1),3.7×10^(14)Ω&3.4×10^(14)Ω·cm,favorable mechanical properties(flexural strength of 401.0 MPa and ILSS of 22.3 MPa),excellent dielectric properties(εof 4.92 and tanδof 0.008)and terrific thermal properties(T_(g )of 167.3℃and T_(HRI) of 199.2℃).

玻璃纤维增强铝合金层板的抗高速冲击性能研究

本文进行了玻璃纤维增强铝合金层板(glass laminate aluminum reinforced epoxy,GLARE)在平头子弹冲击下的高速冲击试验,采用ABAQUS有限元分析软件建立GLARE层板的高速冲击数值模型,研究其在高速冲击作用下的响应及损伤特性,在验证其有效性的基础上,预测了不同直径和不同材料属性的子弹冲击下GLARE层板的抗冲击特性,揭示子弹直径、材料属性和弹头形状对GLARE层板抗高速冲击性能的影响。结果表明:GLARE层板在高速冲击作用下表现出良好的抗冲击性能;弹头形状对GLARE层板抗高速冲击性能影响最大,其次是子弹材料属性,子弹直径对GLARE层板抗高速冲击性能的影响并不显著。

电子级玻纤布在覆铜板上胶过程中的断布原因分析及改善

通过对玻纤布线结产生的原因进行分析,对造成断布的线结在厚度、宽度尺寸上进行量化限定,并针对线结产生主要因素进行改善,从而降低玻纤布线结导致断布风险;通过对胶液杂质产生的原因进行分析,识别胶液过滤过程中的风险点,并进行有效预防,进一步降低胶水杂质对断布的影响。

基于木装饰板与TRC薄板叠合的幕墙装饰材料的研究

通过研究玻璃纤维掺入量对增强混凝土的影响,将环保型木装饰板与织物增强混凝土(TRC)相结合,制成了一种新型绿色的叠合薄板T-TRC(Timber-textilereinforcedconcrete)。通过对增强混凝土的研究表明:当玻璃纤维掺入量为2.0%(体积分数)时,其抗压强度可达58.7MPa,表现最佳。并对以其作为基体所制得的复合材料叠合薄板的界面粘结性和抗弯性能的研究表明:T-TRC构件在102.6kN的极限荷载下,滑移量仅为2.48mm,表现出了优异的粘结性和承载力;在木板和混凝土的单向抗弯试验中,即使在39.6kN的极限荷载下,TTRC叠合薄板间均未发生开脱现象,具有良好的整体性和安全性,这为T-TRC在作为绿色建筑幕墙和模块化建筑板材方面的应用提供了参考。