Simulation of Low Velocity Impact Induced Inter- and Intra-Laminar Damage of Composite Beams Based on XFEM

In this paper, the Inter-Fiber Fracture (IFF) criterion of Puck failure theory based on the eXtended Finite Element Method (XFEM) was implemented in ABAQUS code to predict the intra-laminar crack initiation of unidirectional (UD) composite laminate. The transverse crack path in the matrix can be simulated accurately by the presented method. After the crack initiation, the propagation of the crack is simulated by Cohesive Zoom Model (CZM), in which the displacement discontinuities and stress concentration caused by matrix crack is introduced into the finite element (FE) model. Combined with the usage of the enriched element interface, which can be used to simulate the inter-laminar delamination crack, the Low Velocity Impact (LVI) induced damage of UD composite laminate beam with a typical stacking of composite laminates [0₅/90₃]_S is studied. A complete crack initiation and propagation process was simulated and the numerical results obtained by the XFEM are consistent with the experimental results.     

嵌入式共固化复合材料阻尼结构低速冲击性能的数值模拟

Abstract：Embedded and co-cured composite damping structure is a new damping processing structure, which can be widely used in high-tech fields such as aviation, aerospace, high-speed train, etc. Explicit dynamic analysis software LS-DYNA was used to simulate low velocity impact on embedded and co-cured composite damping structure panels. The simulation results are compared with the experimental data to illustrate the validity of modeling and calculation method. The result of simulation shows that the impact resistance of embedded and co-cured composite damping structure is much higher than composite structure without viscoelastic damping material.     

T300/QY8911层合板低速冲击试验及有限元模拟

对T300/QY8911复合材料层合板进行了低速冲击试验研究及数值仿真模拟。通过自由落体装置对层板进行冲击,并使用超声C扫描技术检测了层板冲击后的损伤状态,获得了不同能量下层板内部的损伤面积。建立了用于预测复合材料层合板在低速冲击作用下损伤演化的3D有限元模型,模型包含了用于模拟分层损伤的界面元和用于模拟纤维断裂、纤维挤压、基体开裂、基体挤裂等面内损伤形式的3D实体单元。该模型考虑了面内基体损伤对层间强度的影响。本文中的数值仿真结果和试验结果的对比验证了模型的合理性和有效性,文中还分析了影响低速冲击后层板内部分层面积的主要因素。     

平面编织复合材料层压板低速冲击后的压缩失效

采用超声C扫描检测、断口分析、有限元分析等方法研究低速冲击损伤对G803/5224与G827/5224两种平面编织复合材料层压板失效行为的影响。结果表明,低速冲击后压缩载荷作用下,G803/5224层压板最终为剪切分层失效,G827/5224层压板最终为剪切屈曲失效,两种层压板低速冲击后压缩的失效模式与未受损伤层压板基本相同。建立了平面编织复合材料层压板的损伤扩展与失效模型,该模型的计算结果与试验结果吻合较好,可用于平面编织复合材料层压板的失效仿真。     

Detecting Low Velocity Impact Damage in Composite Plate Using Nonlinear Acoustic/Ultrasound Methods

The objective of this work was to image the presence of impact damage by monitoring the nonlinear response of damaged carbon/epoxy composite samples. The presence of microcracks, debonding, delamination, etc… induce the material to behave in a nonlinear elastic fashion highlighted by the presence and amplitude of harmonics in the spectrum of the received signal when the sample is periodically excited at one of its resonance frequencies. The sensitivity of a second harmonic imaging technique (SEHIT) based on material nonlinear elastic effect known as second harmonic generation (SHG) was investigated. The proposed imaging process was used to detect barely visible impact damage (BVID) due to low velocity impact (<12 J). The results showed that the SEHIT methods appear to be highly accurate in assessing the presence and magnitude of damage with a very promising future for both NDT and possibly structural health monitoring (SHM) applications. Moreover the technique was validated with two conventional NDT techniques: pulse thermography and thermosonics. The first NDT method failed in detecting the damage on the impacted face. The second technique was capable of localising and quantifying the damage on the impacted surface agreeing well with the results obtained using the proposed nonlinear imaging method.     

碳纤维复合材料层合板低速冲击损伤应力分析

目的 为掌握碳纤维复合材料板在低速冲击载荷作用下的损伤规律,延缓失效破坏,对其冲击损伤的应力状态进行研究。方法 基于ABAQUS平台,建立碳纤维复合材料层合板低速冲击有限元模型,采用Hashin失效准则和VUMAT用户子程序,对碳纤维复合材料层合板的冲击过程进行数值模拟,同时考虑层合板层内与层间失效,以此来研究低速冲击条件下复合材料的损伤机理,分析冲击损伤过程中的应力变化趋势,讨论应力的分布状态。重点研究铺层角度及铺层距离冲头远近对应力的影响。结果 不同角度铺层的应力传播轨迹均沿着纤维方向和垂直于纤维方向同时扩展,应力均先增加至极限值而后迅速下降;铺层角度越大,板料的承载能力越弱,0°铺层的极限应力为1 432 MPa,而90°铺层的极限应力降至1 206 MPa;离冲头越远的铺层应力越小,达到峰值的时间更早且率先下降,说明远离冲头的铺层更早发生失效。结论 揭示了碳纤维层合板在低速冲击载荷作用下的应力状态及其对损伤的影响规律,能够为复合材料层合板零件设计提供参考。     

基于有限元仿真的简支梁结构损伤分析

分析了简支梁结构的振动特性,建立了该结构损伤前后的有限元分析模型,模拟计算了简支梁结构在未损伤、一个损伤、两个损伤和三个损伤状况下的固有频率和振型,重点研究了不同损伤状况对它们的影响.发现损伤裂纹可使简支梁结构的固有频率降低,且其降低幅度随裂纹深度增大而增大,但不同位置的裂纹所产生的影响并不相同.模拟计算结果对简支梁结...     

低速冲击下复合材料层合板损伤分析

根据低速冲击下复合材料层合板的分层损伤机理,发展了一种分层失效准则,该准则同时考虑了层间拉应力、层间剪应力和基体开裂等因素对分层损伤的影响,并在损伤分析中,区分了冲击正面由挤压应力引起的纤维挤压损伤和冲击背面由弯曲拉应力引起的纤维断裂损伤,模拟了纤维断裂、纤维挤压、基体开裂、基体挤压、分层等五种损伤的起始和扩展过程,完善了作者以前发展了低速冲击逐渐累积损伤模型.通过与实验结果进行比较,验证了模型的合理性.     

泡沫铝夹层结构复合材料低速冲击性能

以泡沫铝为夹芯材料,玄武岩纤维(BF)和超高分子量聚乙烯纤维(UHMWPE)复合材料为面板,制备夹层结构复合材料。研究纤维类型、铺层结构和芯材厚度对泡沫铝夹层结构复合材料冲击性能和损伤模式的影响规律,并与铝蜂窝夹层结构复合材料性能进行对比分析。结果表明:BF/泡沫铝夹层结构比UHMWPE/泡沫铝夹层结构具有更大的冲击破坏载荷,但冲击位移和吸收能量较小。BF和UHMWPE两种纤维的分层混杂设计比叠加混杂具有更高的冲击破坏载荷和吸收能量。随着泡沫铝厚度的增加,夹层结构复合材料的冲击破坏载荷降低,破坏吸收能量增大。泡沫铝夹层结构比铝蜂窝夹层结构具有更高的冲击破坏载荷,但冲击破坏吸收能量较小;泡沫铝芯材以冲击部位的碎裂为主要失效形式,铝蜂窝芯材整体压缩破坏明显。     

SMA杂交复合材料板低速冲击响应研究

本应用有限单元法，研究了形状记忆合金(SMA)对复合材料板低速冲击响应性能的影响。研究中，通过分析对比不同SMA体积含量复合材料板的低速冲击响应，得出SMA能的效地改善复合材料板低速冲击响应性能的结论，其中，SMA体积含量为0．3的复合材料板的最大挠度大约减少了30％。     

低速冲击下层间增韧复合材料层压板损伤行为研究

为考察“离位”技术对双马来酰亚胺复合材料层压板层间增韧效果,对增韧程未增韧的两种双马复合材料层压板进行低速冲击性及冲击后压缩剩余强度实验研究.结果表明:经过“离位”增韧的双马复合材料层压板层间形成了热塑性树脂/热固性树脂双连续的结构,该结构不仅改善了材料的损伤阻抗,使其表面凹坑深度更明显,而且还大大提高了材料的损伤容限.     

复合材料飞轮损伤与断裂的结构模拟

本文对复合材料飞轮的受力与损伤情况进行了分析;设计了多种模拟复合材料飞轮的断裂与损伤的静态加载结构,这些结构为用声发射方法检测复合材料飞轮的断裂与损伤的研究工作带来了很大方便,实验证明是可行性的.     

有限元模拟在研究弹丸冲击钢板过程中的应用

综述了有限元模拟在研究弹丸冲击钢板过程中的应用,对几何模型的建立、材料模型及参数的确定、网格的划分和接触法则的定义进行描述和推荐。指出影响抗弹性能的主要因素如弹丸和钢板的材质、弹丸的速度和几何形状、钢板倾斜和复合结构等,均可进行有限元模拟研究。对钢板和弹丸的破坏形貌、应力应变分布、钢板的弹道极限、弹丸速度和加速度随时间的变化、钢板和弹丸的内能变化等有限元模拟结果进行了分析,最后对有限元模拟的局限性进行了说明。     

Experimental Study and Numerical Modelling of Low Velocity Impact on Laminated Composite Reinforced with Thin Film Made of Carbon Nanotubes

In this work, polymer laminated composites based on Epon 862 Epoxy resin, T300 6 k carbon fibers and carbon nanotubes (CNTs) were tested with the aim to elucidate the effect of CNTs on impact properties including impact force and capacity to absorb impact energy. The polymer matrix was reinforced by a random distribution of CNTs with fraction ranging from 0.5 to 4.wt%. Composite panels were manufactured by using the infusion process. Taylor impact test was used to obtain the impact response of specimens. Projectile manufactured from a high strength and hardened steel with a diameter of 20 mm and 1.5 kg of mass was launched by a compressed gas gun within the velocity of 3 m/s. Impact force histories and absorbed energy of specimens were recorded. A numerical model was employed to simulate the impact performance. This model has been accomplished by forming a user established subroutine (VUMAT) and executing it in ABAQUS software. Finally, the effect of CNTs amount on dynamic properties of laminated composites was discussed.     

The Influence of the Boundary Conditions on Low‐Velocity Impact Composite Damage

Abstract: The objective of this work was to study the influence of the boundary conditions on low‐velocity impact behaviour of carbon‐epoxy composite plates. Experimental work and numerical analysis were performed on [0₄,90₄]_s laminates. The influence of different boundary conditions on the impacted plates was analysed considering rectangular and square plates. The X‐radiography was used as a non‐destructive technique to evaluate the internal damage caused by impact loading. A three‐dimensional numerical analysis was also performed considering progressive damage modelling. The model includes three‐dimensional solid elements and interface finite elements including a cohesive mixed‐mode damage model, which allows simulating delamination between different oriented layers. It was verified that plate’s boundary conditions have influence on the delaminated area. Good agreement between experimental and numerical analysis for shape, orientation and size of the delamination was obtained.     

蜂窝铝的面内动态冲击有限元研究

目的研究双壁厚蜂窝铝的面内动态冲击力学行为。方法利用Ansys/LS-DYNA有限元软件,建立双壁厚蜂窝铝有限元模型,分析蜂窝铝壁厚和冲击速度对蜂窝铝面内变形模式和平台应力的影响。结果随着冲击速度的增大,在蜂窝铝的压缩方向上观测到3种变形模式,获得了变形模式转换的临界速度,并给出了临界速度与厚跨比的关系式。计算了不同冲击速度和厚跨比下蜂窝铝的平台应力。结论变形模式对平台应力有很大的影响,不同的变形模式下呈现不同的规律:准静态模式时,平台应力与冲击速度无关;过渡模式和冲击模式时,平台应力随着冲击速度v的增大而增大,分别与v 1.5和v2成线性关系。根据有限元结果,拟合得到了不同的变形模式下平台应力与冲击速度的经验公式。     

复合材料层合板冲击损伤及剩余强度研究进展

综述了受低速冲击后复合材料层合板的损伤研究进展,重点介绍了倍受复合材料工程结构设计师所关注的含损复合材料层合板的剩余拉伸及压缩强度问题,最后对有待于进一步研究的问题进行了展望.     

Simulation of High Velocity Impact on Composite Structures - Model Implementation and Validation

High velocity impact on composite aircraft structures leads to the formation of flexural waves that can cause severe damage to the structure. Damage and failure can occur within the plies and/or in the resin rich interface layers between adjacent plies. In the present paper a modelling methodology is documented that captures intra- and inter-laminar damage and their interrelations by use of shell element layers representing sub-laminates that are connected with cohesive interface layers to simulate delamination. This approach allows the simulation of large structures while still capturing the governing damage mechanisms and their interactions. The paper describes numerical algorithms for the implementation of a Ladevèze continuum damage model for the ply and methods to derive input parameters for the cohesive zone model. By comparison with experimental results from gas gun impact tests the potential and limitations of the modelling approach are discussed.     

纤维增强聚合物基复合材料低速冲击研究进展

综述了连续纤维增强聚合物基复合材料的低速冲击响应研究进展。讨论了测试方法及相关影响参数,例如冲头的形状、冲击速率对复合材料冲击的影响;介绍了冲击损伤的类型,进一步描述了层压板结构参数(如层合板厚度,铺层和缝纫)、复合材料组分材料性能(如纤维,树脂和纤维/树脂界面)以及预应力、环境条件等的影响;提出了纤维增强聚合物基复合材料冲击响应研究今后的发展方向。     

2D C/SiC复合材料低速冲击损伤研究

通过2D C/SiC复合材料的低速冲击试验和冲击后压缩试验,以及超声C扫描和红外热波两种无损检测方法,研究了冲击能量与冲击损伤的关系及其对压缩性能的影响.结果表明:C/SiC具有较好的损伤容限能力,冲击能量低于1.5J时几乎无目视损伤,高于9J时有被击穿的趋势.冲击后的名义压缩强度和压缩模量随着冲击能量的增加呈下降趋势,最多分别下降了44.7%和16.9%.