Thermal influence on surface layer of carbon fiber reinforced plastic (CFRP) in grinding

In this study, we investigated thermal influence on surface layer of CFRP in grinding with heat conduction analysis using grinding temperature at wheel contact area on dry and wet condition. Moreover, the thermal affected layer was analyzed through an experiment to examine the temperature of glass transition and thermal decomposition of the matrix resin that composes the CFRP used in this study. The influence of thermal effect on grinding of CFRP was verified based on observation of ground surface finish after grinding using SEM and the measurement of surface roughness. From the measurement result of DSC (Differential Scanning Calorimetry),TG-DTA (Thermogravimetry-Differential Thermal Analysis), It was found that the thermal affected layer of CFRP includes a layer in which the matrix resin is changed in quality by exceeding the glass transition temperature and a layer in which the matrix resin is thermally decomposed by exceeding the thermal decomposition temperature. In addition, it was found that the surface roughness was significantly reduced if the thermal affected layer with thermal decomposition was generated. In each grinding atmosphere, it tended to increase of grinding temperature at wheel contact area with increasing in the setting depth of cut. In the case of dry grinding, grinding temperature at wheel contact area increased up to t thermal decomposition temperature of the matrix resin. However, in the case of the wet grinding, grinding temperature at wheel contact area did not increase until thermally decomposition temperature. From the result of simulation about thermal affected layer, influence of grinding heat increased with increasing in the setting depth of cut. Ultimately, the thermal affected layer with thermal decomposition was generated in dry grinding. Moreover, from the results of SEM observation, it was confirmed that the surface finish properties deteriorated significantly due to thermal decomposition of the matrix resin in the case of Δ = 400 μm in the setting depth of cut at fiber angle θ = 0°. On the other hand, it was confirmed that the micro damage of carbon fiber was occurred in wet grinding at each setting depth of cut.     

Performance of plastic gear made of carbon fiber reinforced poly-ether-ether-ketone

A carbon fiber (CF) reinforced poly-ether-ether-ketone (PEEK) gear was prepared by injection molding, and its gear performance was evaluated. It was found that the wear process of the CF reinforced PEEK gear significantly varied depending on the test conditions, such as the kind of the partner gear combined and whether a lubricant exists on the engagement region or not. It was assumed that the existence of transfer film at the engagement region, the affinity between PEEK and CF, the compression modulus as well as surface hardness of the partner gear, and the characteristics of CF play a role of differentiation in the wear depth.     

Thrust force and delamination of core-saw drill during drilling of carbon fiber reinforced plastics (CFRP)

Due to the inherent anisotropy and inhomogeneous nature of polymer-based composite materials, their cutting mechanism differs in many respects from conventional metallic materials. Amongst all machining operations, drilling using a twist drill is the most commonly applied method for generating holes for riveting and fastening structural assemblies. Most of the previous research correlates the drill geometry and feed rate to thrust force and delamination on the performance of a twist drill. The Taguchi method has been used to solve many engineering problems. In this investigation, drilling-induced thrust force and delamination by core-saw drill during drilling CFRP laminates were selected as quality character factors to optimize the drilling parameters to obtain the smaller-the-better characteristics. For thrust force and delamination quality character factors, the optimum conditions in drilling were also A₁B₁C₃, (i.e., diameter ratio = 0.55, feed rate = 8 mm/min and spindle speed = 1,200 rpm).     

Performance of plastic gear made of carbon fiber reinforced poly-ether-ether-ketone: Part 2

Five kinds of PEEK/CF composites, made by blending poly-ether-ether-ketone (PEEK) with three kinds of PAN type carbon fibers (CFs) and two kinds of pitch type CFs respectively, were injection-molded into gears. Their gear performance such as the load capability and the wear of tooth were evaluated. The wear properties of PEEK/CF gears extremely varied depending on the kinds of CFs, when the same type gears were combined and grease was initially applied. Also, the load capabilities were significantly influenced by the affinity between PEEK and CF. A composite gear reinforced with CF of the highest density indicated the highest load capability irrespective of the test conditions, due to the lowest abrasive property of the CF as well as the excellent affinity between PEEK and CF. Its load capability under a high temperature running condition was found to be superior to that of polyamideimide (PAI) composite gear or polyphenylenesulphide (PPS) composite gear.     

基于非接触光声成像的碳纤维增强复合材料冲击损伤检测方法

为了探究碳纤维增强复合材料(CFRP)的损伤机制并对其制造过程进行质量监控,对 CFRP 的冲击损伤区域进行了高 分辨无损检测。 构建了全光式非接触光声显微(AONC-PAM)成像系统,利用自主开发的光学吸收结合背向散射的双对比度成 像模式,对 CFRP 在不同冲击能量下的损伤区域进行高分辨率无损检测。 实验结果显示,AONC-PAM 系统的空间分辨率为 2. 9±0. 5 μm;双对比度成像策略能以 2 s/ 帧的速率同时获得基于光学吸收和表面散射特性的图像及两者叠加的双对比度图 像;AONC-PAM 系统显示了比通用明场显微镜系统更多的成像细节,包括碳纤维分布和其他微观缺陷如纤维断裂、错位、缺束 和褶皱,可检测的微观缺陷尺寸达 10~ 20 μm,并实现了损伤区域的精准量化。     

连续纤维增强玻璃钢球阀研究

介绍了由材料性能试验获取的连续玻璃纤维增强复合材料的力学性能,包括沿各个不同方向的拉伸、压缩、剪切、弯曲等性能参数,并依据这些性能参数,研究连续纤维增强玻璃钢球阀的设计要点,导出其详细设计公式。通过对材料组成及制备工艺进行改进,使得设计出的玻璃钢球阀较国内普通的玻璃钢球阀力学性能更为优秀。     

涂层钻头钻削碳纤维复合材料的轴向力研究

不同刀具材料对碳纤维复合材料的加工有较大的影响。通过合理选择钻头的基体材料和涂层材料,基于正交试验综合分析不同涂层材料、主轴转速及进给速度对钻削轴向力的影响。试验结果表明,涂层材料对轴向力的影响最大,涂层钻头的钻削轴向力比无涂层YG6X钻头小很多,类金刚石涂层(DLC)钻头最小。TiAlN和TiCN涂层钻头都有不同程度的磨损,DLC钻头的耐磨性和加工质量都远远高于其他涂层。     

Lensed plastic optical fiber employing hyperbolic end filled with high-index resin using electrostatic force

The step-index (SI) and graded-index (GI) plastic optical fibers (POFs) are strong candidates for short-distance transmission, fiber-to-the-home (FTTH) networks, automobile applications and interchip interconnections. The GI POFs which has been proven to reach distances as long as 1 km at 1.25 Gb/s has a relatively low NA. Therefore, the efficient coupling of GI POFs to the light source has become critical to the power budget in the system. Forming a lens-like structure directly on the fiber end is preferred for simplicity of fabrication and packaging, such as polishing and fusion, combing different fibers with the cascaded fiber method and hydroflouride (HF) chemical etching. These approaches are well established, but applicable only to glass. This work proposes a novel structure of a lensed plastic optical fiber (LPOF). The fabrication of the LPOF is demonstrated and the coupling efficiency exceeds 72%.     

An analytical approach to cutting force prediction in milling of carbon fiber reinforced polymer laminates

ABSTRACT

A prediction model of cutting force for milling multidirectional laminate of carbon fiber reinforced polymer (CFRP) composites was developed in this article by using an analytical approach. In the predictive model, an equivalent uniform chip thickness was used in the case of orthogonal plane cutting, and the average specific cutting energy was taken as an empirical function of equivalent chip thickness and fiber orientation angle. The parameters in the model were determined by the experimental data. Then, the analytical model of cutting force prediction was validated by the experimental data of multidirectional CFRP laminates, which shows the good reliability of the model established. Furthermore, the cutting force component of flank contact force was correlated with the surface roughness of workpiece and the flank wear of tool in milling UD-CFRP composites. It was found that surface quality as well as flank wear has a co-incident varying trend with the flank contact force, as confirmed by the observations of the machined surfaces and tool wear at different fiber orientations. So, it can be known that low flank contact force be required to reduce surface damage and flank wear.     

Lensed plastic optical fiber with an aspherical fiber end formed by joining an aspherical plastic lens and a plastic optical fiber using laser transmission welding

In optical communication systems which require the coupling of the light source to the fiber, efficient coupling can be practically realized either using a separate lens or by direct formation of the lens at the fiber end. A novel lensed plastic optical fiber (LPOF) is presented with efficient coupling of the plastic optical fibers with a light source. An aspherical plastic lens was bound with a flattened plastic fiber end by laser transmission welding (LTW) to form an aspherical fiber endface which can provide better coupling efficiency than a spherical fiberface. An analysis demonstrates that LTW can offer strong welding with small heat affected zones that are appropriate for commercial use. In this study a useful method for manufacturing lensed-end fibers is developed and demonstrated experimentally.     

Development of cutting force prediction model for carbon fiber reinforced polymers based on rotary ultrasonic slot milling

Carbon fiber reinforced polymers (CFRP) have got widely increased applications in aviation, defense and other industries due to their properties of high specific strength/stiffness, high corrosion resistance and low-thermal expansion. The issues like excessive cutting forces and machining damages are encountered in machining due to heterogeneity, anisotropy and low heat dissipation of these materials. The cutting forces are required to be predicted/minimized through modeling. In this article, the novel axial and feed cutting force model has been developed and validated through rotary ultrasonic slot milling of CFRP composites. The variations less than 10% have been found between the measured and corresponding simulated values of the cutting forces. However, some higher variations have also been observed in the few cases mainly due to heterogeneity and anisotropy of such material. The cutting depth is a significant parameter for axial and feed forces, while the feed rate is significant for the axial force. Both the forces decreased with the increase of spindle speed, while they increased with the increase of feed rate and cutting depth. The developed models have been found to be robust and can be applied to optimize the cutting forces for such materials at the industry level.     

Integration of cutting force control and chatter suppression control into automatic cutting feed adjustment system design

Abstract

This study designed an automatic cutting feed adjustment system for computer numerical control (CNC) turning machine tools, which integrate the operational characteristics of cutting force control and chatter suppression control to shorten the machining time and maintain the quality of workpieces. The setting of appropriate machining conditions (such as cutting feed, spindle speed and depth of cut) to consider both machining quality and efficiency often causes difficulties for machine tool operators. Therefore, this study uses cutting force control to design an automatic cutting feed adjustment method for cutting tools, and then, the chatter suppression control design is used to modify the cutting force command to suppress cutting chatter. The experimental results of the CNC turning machine tool show that the use of the cutting force control to adjust the cutting feed can shorten the machining time; however, the cutting chatter results in larger surface waviness on the workpiece surface. When the cutting force command is properly modified by actuating the chatter suppression control, the workpiece shows better surface roughness with prolonged machining time. Therefore, the cutting tests demonstrate that the proposed system is feasible for satisfying the machining requirements of the manufacturing processes of mechanical parts for high speed and high accuracy.     

An investigation of the characteristics of the stationary feed motor current in NC machines

The cross-feed directional cutting force acts normal to the machined surface of a workpiece. It is important to estimate and control this force, since it directly affects the machined surface. However, using the current supplied to a stationary motor to predict the cutting state poses difficulties, because of the current's somewhat undesired behaviour. In this paper, a largely empirical approach was used to help resolve this problem. We show that the current's undesired behaviour is related to infinitesimal rotations of the motor. Subsequently, the relationship between the current and the cutting force was identified with an error of less than 15%. The predictions obtained using two machine tools with different characteristics were compared to confirm the validity of the method when investigating the characteristics of the stationary feed motor current.     

Hole quality in longitudinal–torsional coupled ultrasonic vibration assisted drilling of carbon fiber reinforced plastics

Frontiers of Mechanical Engineering - Carbon fiber reinforced plastic (CFRP) composites are extremely attractive in the manufacturing of structural and functional components in the aircraft...     

响应曲面法FDM碳纤维增强ABS制件精度研究

熔融沉积成型(Fused Deposition Modeling,FDM)碳纤维增强ABS丝材相对于ABS丝材,具有强度高、质量轻等优点,其成型质量取决于FDM成型机参数的选择.从成型机参数中选取热床温度、喷头温度、扫描速度以及层高作为研究因素,并对这4个因素进行单因素研究,得出各因素影响制件成型质量的合理范围.以上述...     

大口径玻璃钢管内嵌结构优化设计

分析了大口径玻璃钢管内嵌结构的常用设计方法,在此基础上进行了玻璃钢管内嵌结构的改进设计,并借助Inventor软件进行了三维实体建模比较和有限元应力分析,验证了改进后的内嵌结构性能得到了部分优化,并制作了结构实物模型投入实际应用.     

碳复合材料钻孔加工性研究

从刀具材料,几何角度,切削用量等几个方面分析了碳复合材料钻孔工艺性和表面质量,给出了改善复合材料钻孔质量的工艺参数。     

碳纤维复合材料-钛合金层板钻孔质量研究

对比钻削碳纤维复合材料(CFRP),碳纤维复合材料-钛合金层板(CFRP-Ti),得出钻削CFRP-Ti时的CFRP入口分层、孔径误差、形状误差以及孔的表面粗糙度均比单独钻削CFRP时的要差.其原因是CFRP在上层,当钻削钛合金层时,一方面轴向钻削力大,钻削过程不平稳;另一方面钛合金的钻屑为螺旋长条状,这些都会影响已形成的孔壁.尤其在高转速下,此影响更为严重.     

Kevlar-129纤维复合材料的弹道侵彻数值仿真

基于 AUTODYN有限元软件,研究了Kevlar-129纤维增强复合材料的抗侵彻性能。通过质量为10 g的 FSP破片对厚度为8、10、12、14、16以及18 mm 的六组 Kevlar 纤维靶板进行撞击模拟,获得了 FSP破片贯穿6组靶板的弹道极限,并分析了靶板的弹道极限、比吸收能随板厚的变化关系。结果表明,在板厚8-18 mm范围内,Kevlar纤维靶板的弹道极限随板厚的增加呈线性增长;在此范围内,靶板的比吸收能也呈近似线性增长,但在板厚为10-16 mm时,增长稍缓。对比还发现,比吸收能随板厚的变化规律与靶板面密度的变化规律几乎相同,二者都可用于描述Kevlar-129纤维复合材料靶板在 FSP 破片碰撞下比吸收能的变化。