CFRP正交切削中亚表面损伤量化表征及控制技术研究

发布时间：2018-01-16 16:25

本文关键词：CFRP正交切削中亚表面损伤量化表征及控制技术研究　出处：《哈尔滨工业大学》2017年博士论文　论文类型：学位论文

【摘要】：碳纤维增强树脂基复合材料(Carbon Fiber Reinforced Polymer,CFRP)因其具有优秀的力学性能和高效的制备工艺,目前已经成为航空、航天产业等高科技领域内承力结构件的主要制备材料之一,并被广泛认为是替代传统金属及合金材料的新一代高性能材料。在制备CFRP结构件时,为了减少成型后CFRP内部结构缺陷、保障结构件最终的力学性能和抗疲劳性能,CFRP的成型工艺通常都是一次几净成型的。与此同时,CFRP结构件在实际工程应用中经常需要与金属或其他非金属材料件进行固定或组装,CFRP结构件的二次加工后处理过程在所难免。然而,由于CFRP具有多相性和各向异性的特点,其在加工性能上与各向同性的金属或合金材料完全不同,传统金属材料的加工工艺和经验公式对CFRP来说已不完全适用。特别是,对于CFRP来说,其在加工后在表面和亚表面通常会出现多种类型的损伤失效模式,这些由切削力诱导产生的微观结构缺陷会严重损害CFRP结构件的力学性能和抗疲劳性能。与对CFRP加工性能进行研究相比,对CFRP在加工后产生的缺陷进行科学地表征研究,进而掌握有效控制CFRP加工后亚表面损伤程度的方法也是同样重要的。因此,为了提高CFRP的加工效率、提升CFRP结构件加工后加工面的表面质量与成型尺寸精度,以及控制切削力导致的微观缺陷,本文从研究CFRP的切削加工性能,和加工参数影响下的亚表面损伤程度的表征与分析入手,先后开展了基于正交切削过程的CFRP切削实验研究和有限元仿真研究。在CFRP正交切削实验中,两种常用于工程应用中并具有代表性纤维结构类型的CFRP材料,单向连续碳纤维复合材料层合板和二维平面正交编织碳纤维复合材料层合板被分别用来制备实验用切削加工件。为了表征CFRP的切削加工性能,正交切削过程中的切削力和加工后的表面形貌质量都是本文的重点考察指标。正交切削实验是以单因素实验形式开展的,其中具有多个水平的纤维方向角度、切削速度和切削深度是实验中主要研究因素。一个基于压电式三向测力仪的切削力测量系统被用来获取CFRP在加工过程中的实时的主切削力和切深抗力值,同时金相显微观测法和轮廓仪表征法被分别用来观测和表征两种CFRP加工件加工后产生的损伤破坏形式和表面粗糙度。切削实验发现,CFRP的纤维方向角度对切削力和加工表面质量都有显著影响,并且切削速度的提高和切削深度的降低可以有效提高CFRP的切削表现:对于UD-CFRP来说,切削速度的提高可以使主切削力最大减少142.29N、切深抗力最大减少97.12N、加工后表面粗糙度最大下降5.9068μm,切削深度的提高会使主切削力最大上升143.67N、切深抗力最大上升80.54N、加工后表面粗糙度最大提高10.3689μm;对于Woven CFRP来说,切削速度的提高可以使主切削力最大减少66.06N、切深抗力最大减少37.16N、加工后表面粗糙度最大下降3.9580μm,切削深度的提高会使主切削力最大上升55.06N、切深抗力最大上升33.29N、加工后表面粗糙度最大提高4.4107μm。此外,为了分析切削实验中CFRP加工诱导亚表面损伤的影响因素,一种基于超声无损检测技术的扫描声学显微镜被用来扫描并检测CFRP在加工后的亚表面损伤程度。并且,为了可以对CFRP加工件中由切削力诱导产生的亚表面损伤进行定量分析,一维深度损伤因子Fdep和二维面积损伤因子Fa被建立并借助数字图像分析技术来量化表征超声扫描图像中每个CFRP加工件的亚表面损伤程度。在CFRP正交切削有限元仿真研究中,一个利用用户子程序VUMAT嵌入复合材料失效准则的三维等效均质CFRP正交切削过程有限元模型被成功建立。为了提高仿真精度以及验证该模型的可适用性,将基于四种不同复合材料失效准则有限元模型的仿真结果分别与实验测试值进行对比分析,比照参量包括切削力和亚表面损伤因子。其中,损伤因子中各参量的大小通过Python脚本语言捕捉到的单元信息进行获取。通过与实验结果进行验证后得到,基于HashinPuck准则的UD-CFRP模型在计算四种被考察的目标参量时,平均误差仅为16.44%;而对于Woven CFRP模型来说,Hashin失效准则和HashinPuck准则都有不错的表现,基于HashinPuck准则的Woven CFRP模型计算得到的模拟结果与实验结果的平均误差为8.03%。验证后的有限元模型被用来预测在多组正交切削加工参数下两种不同结构的CFRP的切削力和损伤因子的值,进而提供一个可信的加工参数优化范围,以减少CFRP加工件在加工后的亚表面损伤程度,提高CFRP的切削加工效率。正交切削加工UD-CFRP的最优加工参数组合为,切削速度309.5m/min和切削深度0.1mm;加工Woven CFRP所用加工参数给出优化区间为,切削速度在200m/min以上,同时切削深度小于0.35mm。本文中建立的切削实验研究方案和有限元数值模型可以有效表征CFRP材料的切削加工性能和亚表面损伤行为,同时,利用可量化表征亚表面损伤程度的损伤因子对CFRP加工参数进行优化选择也是切实有效的,具有较好的工程应用前景。
[Abstract]:Carbon fiber reinforced resin matrix composites (Carbon Fiber Reinforced Polymer, CFRP) because of its excellent mechanical properties and efficient preparation process, has become one of the main preparation of aviation materials, structural components for the aerospace industry and other high-tech fields, and is widely considered to be a new generation of high performance material substitution the traditional metal and alloy materials. In the preparation of the CFRP structure, in order to reduce the forming CFRP internal structure, support structure ultimate mechanical properties and anti fatigue performance, molding process of CFRP is usually a few net shape. At the same time, the CFRP structure in practical engineering applications often need to metal or other non-metallic materials are fixed or assembled, two processing CFRP structure of the postprocessing process can hardly be avoided. However, due to the characteristics of CFRP with heterogeneous and anisotropic, the processing performance Completely different from the isotropic metal or alloy material, the traditional processing technology of metallic materials and the empirical formula for CFRP is not fully applicable. In particular, for CFRP, the after processing in the surface and sub surface often appear various types of failure mode, which caused by cutting force induced by micro structure the defects will seriously damage the mechanical properties of CFRP structures and anti fatigue properties. Compared with the research on CFRP processing performance, the defects of CFRP produced after processing of surface science and grasp the method of syndrome, sub surface damage to the effective control of CFRP process is also important. Therefore, in order to improve the machining efficiency of CFRP CFRP, lifting structure processing after processing the surface quality and size precision molding, and micro defects in the control of cutting force, the cutting of the CFRP, and Characterization and analysis of the degree of subsurface damage under the influence of processing parameters, has carried out the experimental study of CFRP cutting orthogonal cutting process and finite element simulation. Based on CFRP orthogonal cutting experiments, two kinds of commonly used in engineering application and representative fiber structure type CFRP unidirectional carbon fiber composite material laminates and two dimensional orthogonal woven carbon fiber composite laminates were used for the preparation of cutting experiments. In order to use the cutting performance characterization of CFRP, the surface morphology quality of orthogonal cutting process in cutting force and after processing are the key indexes in this paper. The orthogonal cutting experiment is based on the single factor experiment carried out in the form of fiber direction, having a plurality of levels, cutting speed and cutting depth is the main factor of the experiment. Based on a piezoelectric three to force measuring instrument The cutting force measuring system is used to obtain real-time CFRP main cutting force during machining and deep cutting resistance, and metallographic observation method and instrument method are used to outline syndrome observation and characterization of two CFRP processing after processing the damage form and surface roughness. Cutting experiments showed that the fiber orientation angle CFRP has a significant impact on the cutting force and the machined surface quality, and decreased with increasing cutting speed and cutting depth can effectively improve the cutting performance of CFRP: the UD-CFRP, the increase of the cutting speed can make the main cutting force reduced maximum 142.29N, maximum depth of cut resistance reduced 97.12N, after processing the surface roughness of the largest decline in 5.9068 m, the cutting depth will improve the main cutting force increased maximum 143.67N, maximum depth of cut resistance 80.54N increased after processing, the surface roughness is the largest increase of 10.3689 mu m; for Woven CFR P, the increase of the cutting speed can make the main cutting force reduced maximum 66.06N, maximum depth of cut resistance reduced 37.16N, after processing, the surface roughness is the largest decline in 3.9580 m, the cutting depth will improve the main cutting force increased maximum 55.06N, maximum depth of cut resistance 33.29N increased after processing, the surface roughness is the largest increase of 4.4107 mu m. In addition, in order to analyze the influence factors of CFRP process induced by sub surface damage cutting experiments, a scanning acoustic microscope based on ultrasonic nondestructive testing technology is used to scan and detect CFRP after processing sub surface damage. And, in order to can be used for the quantitative analysis of sub surface generated by the cutting force induced in CFRP processing one dimensional depth of damage, the damage factor Fdep and the two-dimensional area damage factor Fa was established with each CFRP processing of the quantitative characterization of ultrasonic scanning image in digital image analysis technology of sub table The surface damage degree. In the study of CFRP orthogonal cutting finite element simulation, failure criterion using a user subroutine VUMAT embedded composite 3D equivalent CFRP orthogonal cutting finite element model was successfully established. In order to improve the accuracy and applicability of the simulation to verify the model, four kinds of simulation finite element model of different composite failure criterion based on the results of material respectively and the experimental values were compared and analyzed according to the parameters including cutting force and sub surface damage factor. Among them, the parameters of the size of the damage factor through Python scripting language to capture the information obtained by the unit. With the result of experiment, the HashinPuck criterion of UD-CFRP model in the calculation of four kinds of the target parameters based on the average error is only 16.44%; and for the Woven CFRP model, Hashin failure criterion and HashinPuck criterion are Have a good performance, the average error of simulation results calculated by Woven CFRP model based on HashinPuck criterion and experimental results for the finite element model of 8.03%. test was used to predict the orthogonal cutting parameters under two different structures of CFRP cutting force and damage factor value, and then provide a processing parameter credible optimization range, in order to reduce the CFRP processing sub surface damage after processing, improve the machining efficiency of CFRP. The optimal processing parameters for UD-CFRP orthogonal cutting, cutting speed and cutting depth of 309.5m/min 0.1mm; Woven CFRP for processing parameters are optimized for processing interval, the cutting speed is above 200m/min, cutting the processing performance and sub surface and the cutting depth is less than 0.35mm. the cutting method of experimental research and finite element numerical model can effectively characterize CFRP materials It is also effective to optimize the processing parameters of CFRP by quantifying the damage factors of sub surface damage degree, and has a good engineering application prospect.

【学位授予单位】：哈尔滨工业大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TQ327.3;TB332

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