今日更新:International Journal of Solids and Structures 1 篇,Mechanics of Materials 1 篇,International Journal of Plasticity 3 篇,Thin-Walled Structures 6 篇
A multi-step auxetic metamaterial with instability regulation
Penghui Yu, Peijie Zhang, Qingxiang Ji, Fan Yang, Xiaojun Tan, Xueyan Chen, Huifeng Tan, Vincent Laude, Muamer Kadic
doi:10.1016/j.ijsolstr.2024.113040
一种具有失稳调节的多步增减超材料
A stable deformation mode is highly desired for mechanical metamaterials, especially when coupled with a negative Poisson’s ratio. However, such metamaterials often face challenges in terms of scalability toward large deformation or strain. In response, we propose a multi-step hierarchical auxetic metamaterial design paradigm, incorporating a series of incrementally scaled-down structures with same scale factor α into a re-entrant framework. This design enables instability regulation and multi-step deformation capabilities while preserving auxetic behavior, even under significant strain. Such multi-step metamaterials exhibit excellent properties, including tailored multi-phase compression modulus and strength, along with an enhanced energy absorption capacity that is as large as 2.1 times that of the original auxetic metamaterial. Experiments and simulations demonstrate that the deformation mechanism and compression response of the proposed multi-step auxetics are strongly influenced by the reduction factor and the order of the inner structure. A particularly intriguing observation is that the incorporation of embedded microstructures can restore stable deformation, even in the presence of significant initial instability, particularly with a reduction factor of 1/5. At high relative density, its specific energy absorption stands out favorably compared to other configurations, highlighting the success of the recoverable buckling mechanism. This work paves the way for designing multi-step mechanical metamaterials for use in impact resistance and body protection.
机械超材料非常需要稳定的变形模式,尤其是在负泊松比的情况下。然而,这种超材料在大变形或大应变的可扩展性方面往往面临挑战。为此,我们提出了一种多步骤分层辅助超材料设计范例,将一系列具有相同尺度系数 α 的增量缩小结构纳入一个重入框架。这种设计能够调节不稳定性和实现多级变形能力,同时保持辅助行为,即使在巨大应变下也是如此。这种多级超材料表现出卓越的性能,包括量身定制的多相压缩模量和强度,以及增强的能量吸收能力,是原始辅助超材料的 2.1 倍。实验和模拟证明,所提出的多级辅助材料的变形机制和压缩响应受到内部结构的缩减因子和阶次的强烈影响。一个特别有趣的观察结果是,即使存在显著的初始不稳定性,嵌入式微结构也能恢复稳定的形变,尤其是在缩减因子为 1/5 的情况下。在相对密度较高的情况下,与其他结构相比,它的比能量吸收能力更强,这凸显了可恢复屈曲机制的成功。这项工作为设计用于抗冲击和人体保护的多级机械超材料铺平了道路。
Experimental investigation and micromechanical analysis of glass fiber reinforced polyamide 6
Marie-Christine Reuvers, Christopher Dannenberg, Sameer Kulkarni, Klara Loos, Michael Johlitz, Alexander Lion, Stefanie Reese, Tim Brepols
doi:10.1016/j.mechmat.2024.105144
玻璃纤维增强聚酰胺6的实验研究及细观力学分析
Achieving process stability in the thermoforming of fiber reinforced polymer materials (FRPs) for aerospace or automotive manufacturing is usually associated with a costly trial-and-error process, where experimental boundary conditions and other influencing factorsRWTHblau such as, for example, material composition RWTHblau need to be adjusted over time. This is especially true when material phenomena on the microlevel, such as the crystallization kinetics of the polymer matrix or resulting stresses from temperature gradients, are the cause of the process instability. To reduce the experimental effort and reliably predict the material behavior during thermoforming, finite element simulation tools on multiple scales are a useful solution. RWTHblauHereby, incorporating micromechanical phenomena into the model approaches is crucial for an accurate prediction by further reducing the deviation between simulation and experiment, in particular with regard to the underlying nonlinear material behavior. In this work, unit cell simulations on the microscale of a unidirectional glass fiber reinforced polymer (UD GFRP) are conducted to predict effective thermomechanical properties of a single material ply and ascertain the effect of individual ply constituents on the homogenized material behavior. The polymeric matrix material model used was identified in a prior publication with experimental data at various temperatures for polyamide 6 blends with varying degrees of crystallinities. Various randomization methods are tested to generate the unit cells and replicate the composites’ random fiber distributionRWTHblau with a focus on process automation. The simulative results are successfully compared to an experimental study on glass fiber reinforced polyamide 6 tested at various temperatures, demonstrating the potential of the approach to reduce RWTHblauboth time and cost required for material characterization. Finally, the unit cells are used to generate a RWTHblaudatabase RWTHblauto predict untested load cases that will be used in future work to characterize a homogenized macroscopic material model.
在航空航天或汽车制造中实现纤维增强聚合物材料(frp)热成型的过程稳定性通常与一个昂贵的试错过程有关,其中实验边界条件和其他影响因素(例如材料成分)需要随着时间的推移而调整。当微观层面上的材料现象,如聚合物基体的结晶动力学或温度梯度产生的应力,是导致工艺不稳定的原因时,尤其如此。为了减少实验工作量并可靠地预测材料在热成形过程中的行为,多尺度有限元模拟工具是一种有用的解决方案。因此,通过进一步减少模拟与实验之间的偏差,特别是关于潜在的非线性材料行为,将微观力学现象纳入模型方法对于准确预测至关重要。在这项工作中,对单向玻璃纤维增强聚合物(UD GFRP)进行了微尺度的单元胞模拟,以预测单一材料层的有效热力学性能,并确定单个层成分对均匀化材料行为的影响。使用的聚合物基体材料模型在先前的出版物中确定了不同温度下具有不同结晶度的聚酰胺6共混物的实验数据。测试了各种随机化方法来生成单元格,并复 制复合材料的随机纤维分布。模拟结果成功地与玻璃纤维增强聚酰胺6在不同温度下测试的实验研究进行了比较,证明了该方法在减少材料表征所需的rwthblu时间和成本方面的潜力。最后,这些单元格被用来生成rwthblauauto数据库,rwthblauauto预测未测试的载荷情况,这些情况将在未来的工作中用于表征均质宏观材料模型。
Local element segregation-induced cellular structures and dominant dislocation planar slip enable exceptional strength-ductility synergy in an additively-manufactured CoNiV multicomponent alloy with ageing treatment
Kefu Gan, Weiying Huang, Wei Zhang, Ruidi Li, Yong Zhang, Weisong Wu, Pengda Niu, Pengfei Wu
doi:10.1016/j.ijplas.2024.104112
局部元素偏析诱导的细胞结构和主要的位错平面滑移使增材制造的CoNiV多组分合金具有特殊的强度-塑性协同作用
We proposed an additively manufactured equiatomic CoNiV multicomponent alloy (MCA) using a conventional laser powder bed fusion (LPBF) method, and an exceptional strength-ductility synergy of the alloy was attained through a simple post-ageing treatment. Pronounced hierarchical microstructures were achieved in our printed alloys, including heterogeneous grain structures, and intragranular cellular structures composed of interior domain with limited dislocations and cell walls led by significant vanadium local segregation. Besides the outstanding mechanical properties at room temperature of 298 K, a giga-pascal yielding strength (> 1.1 GP) and over 40% uniform elongation were attained in the aged specimen deformed at a cryogenic temperature of 77 K, predominating the mechanical properties of many alloys reported in previous works. Such exceptional performance of the aged alloy can be mainly ascribed to considerable local chemical orders (LCOs), aggravated elemental fluctuation in the alloy matrix, and intensified vanadium segregation at walls of intragranular cellular structures which can strongly interact with dislocations. As a result, a planar slip array of dislocations with an extremely high density, namely large numbers of slip bands that can sustain and transfer high strains, dominates the deformation microstructures, thus efficiently strengthening and toughening the aged alloy, especially at a low temperature like 77 K. The above post-ageing strategy is readily and low-costly employed on additively manufactured MCAs with relatively high stacking fault energy (SFE) and proved as a feasible method to produce high-performance structural materials for extreme conditions.
我们提出了一种增材制造的等原子CoNiV多组分合金(MCA),使用传统的激光粉末床熔合(LPBF)方法,并通过简单的后时效处理获得了合金的特殊强度-塑性协同作用。在我们的打印合金中实现了明显的分层微观结构,包括非均匀晶粒结构,以及由具有有限位错的内部区域和由显著的钒局部偏析引起的细胞壁组成的晶内细胞结构。该合金在室温298 K下具有优异的力学性能,在低温77 K下时效后,其屈服强度达到千兆帕斯卡(> 1.1 GP),均匀伸长率超过40%,优于以往报道的许多合金的力学性能。时效合金的这种特殊性能主要归因于大量的局部化学顺序(lco),合金基体中元素波动加剧,以及与位错强烈相互作用的晶内细胞结构壁上钒偏析加剧。结果,形变组织中出现了密度极高的位错平面滑移阵列,即大量能够承受和传递高应变的滑移带,从而有效地强化和增韧了时效合金,特别是在77 K这样的低温下。上述后老化策略可用于具有较高层错能(SFE)的增材制造MCAs,且成本低,是一种生产极端条件下高性能结构材料的可行方法。
Automated analysis framework of strain partitioning and deformation mechanisms via multimodal fusion and computer vision
Ran Ni, Carl J. Boehlert, Ying Zeng, Bo Chen, Saijun Huang, Jiang Zheng, Hao Zhou, Qudong Wang, Dongdi Yin
doi:10.1016/j.ijplas.2024.104119
基于多模态融合和计算机视觉的应变分配和变形机制自动分析框架
Simultaneously investigating strain partitioning and the underlying deformation mechanisms for both the grain interior and the grain boundary (GB) is essential for understanding the complex plastic deformation of hexagonal close-packed metals. To this end, an automated analysis framework based on high-resolution digital image correlation (HRDIC) and electron backscatter diffraction (EBSD) data fusion and computer vision, integrating nanoscale resolution and a large field of view, is proposed. This framework consists of: (1) HRDIC-EBSD data fusion; (2) Segmenting the strain field into individual grains each with a core and a mantle; (3) Data clustering of the Matrix and slip bands (SBs) for each grain; (4) Full slip system (SS) identification and SS assignment to the SBs. The capabilities of this framework were demonstrated on Mg-10Y during compression. The strain field data, which was segmented into different clusters, including grain mantle, grain core, Matrix, and SBs, was analyzed statistically and quantitatively. The pixel-based slip activity, which considers the SB morphology, was obtained from a statistical perspective. Inter-granular accommodating mechanisms, including GB strain, slip transfer, and GB sliding, were quantitatively analyzed. Overall, this analysis framework, which can be applied to other materials, can automatically and statistically evaluate both nanoscale strain fields and underlying intra- and inter-granular deformation mechanisms grain-by-grain. This work provides valuable experimental insights into plastic deformation and accommodation mechanisms for polycrystals.
同时研究晶粒内部和晶界(GB)的应变分配和潜在的变形机制对于理解六边形密排金属的复杂塑性变形至关重要。为此,提出了一种基于高分辨率数字图像相关(HRDIC)和电子背散射衍射(EBSD)数据融合和计算机视觉的自动化分析框架,集成了纳米级分辨率和大视场。该框架包括:(1)HRDIC-EBSD数据融合;(2)将应变场分割成具有地核和地幔的单个颗粒;(3)各晶粒的矩阵和滑移带(SBs)数据聚类;(4)全滑移系统(SS)的识别和对SBs的SS分配。该框架的性能在Mg-10Y压缩过程中得到了验证。对应变场数据进行了统计和定量分析,并将其划分为不同的簇,包括颗粒地幔、颗粒核、基质和SBs。从统计角度获得了考虑SB形态的基于像素的滑动活动。定量分析了GB应变、滑移传递和GB滑动等颗粒间调节机制。总体而言,该分析框架可以应用于其他材料,可以逐粒自动统计地评估纳米尺度的应变场和潜在的晶内和晶间变形机制。这项工作为多晶的塑性变形和调节机制提供了有价值的实验见解。
Exceptional strength-ductility synergy in the novel metastable FeCoCrNiVSi high-entropy alloys via tuning the grain size dependency of the transformation-induced plasticity effect
Mohammad Sajad Mehranpour, Mohammad Javad Sohrabi, Alireza Kalhor, Jae Heung Lee, Ali Heydarinia, Hamed Mirzadeh, Saeed Sadeghpour, Kinga Rodak, Mahmoud Nili-Ahmadabadi, Reza Mahmudi, Hyoung Seop Kim
doi:10.1016/j.ijplas.2024.104115
新型亚稳FeCoCrNiVSi高熵合金的特殊强度-延性协同作用通过调整晶粒尺寸依赖性的转变诱导塑性效应
In-depth knowledge of the coupling between grain refinement and the transformation-induced plasticity (TRIP) effect in metastable alloys is a viable approach for the improvement of strength-ductility synergy, which needs systematic research with consideration of commercial austenitic stainless steels and novel high-entropy alloys (HEAs). Accordingly, in the present work, two Si-containing metastable HEAs in the Fe47Co30Cr10Ni5V8-xSix system (x = 3 and 6 at.%) were designed, and the TRIP-assisted AISI 304L stainless steel was also considered for comparison. The alloys were processed by cold rolling and annealing to obtain different grain sizes. Reducing the stacking fault energy (SFE) through adjusting chemical composition contributes to minimizing the detrimental effect of grain refinement on the ductility of TRIP alloys, while extremely low SFE must be avoided owing to the fast kinetics of deformation-induced martensitic phase transformation, which leads to the deterioration of ductility. In contrast to AISI 304L stainless steel, a strong TRIP effect was maintained upon grain refinement in the Fe47Co30Cr10Ni5V2Si6 HEA due to the remaining apparent SFE in the appropriate TRIP range. The tuned kinetics of martensitic transformation was found to be responsible for the exceptional ductility (∼65%) of Fe47Co30Cr10Ni5V2Si6 HEA at an ultrahigh tensile strength of 1250 MPa. Therefore, considering the identical trend of SFE with grain size, an appropriate initial SFE value is important for tuning the grain size dependency of the TRIP effect. Moreover, the ultrahigh strength was attributed to the high volume fraction of α΄-martensite as well as the high strength of the martensite phase due to the high Si content. Accordingly, for achieving strong-yet-ductile HEAs, a high Si content is recommended to benefit from solid solution strengthening in the martensite phase, a specially-designed chemical composition is needed for attaining a high volume fraction of α΄-martensite, and SFE should be in a desirable range to tune the kinetics of martensitic phase transformation.
深入了解可代谢合金中晶粒细化与转化诱导塑性(TRIP)效应之间的耦合关系是提高强度-电导率协同效应的可行方法,这需要对商业奥氏体不锈钢和新型高熵合金(HEAs)进行系统研究。因此,在本研究中,设计了 Fe47Co30Cr10Ni5V8-xSix 体系(x = 3 和 6 at.%)中的两种含 Si- 的易析出高熵合金,并将 TRIP 辅助的 AISI 304L 不锈钢作为比较对象。合金经过冷轧和退火处理,以获得不同的晶粒大小。通过调整化学成分降低堆叠错能(SFE)有助于最大限度地减少晶粒细化对 TRIP 合金延展性的不利影响,同时必须避免极低的 SFE,因为形变引起的马氏体相变的动力学速度很快,会导致延展性恶化。与 AISI 304L 不锈钢相比,Fe47Co30Cr10Ni5V2Si6 HEA 在晶粒细化后仍能保持较强的 TRIP 效应,这是因为在适当的 TRIP 范围内仍存在表观 SFE。经过调整的马氏体转变动力学被认为是 Fe47Co30Cr10Ni5V2Si6 HEA 在 1250 MPa 的超高拉伸强度下具有优异延展性(∼65%)的原因。因此,考虑到 SFE 随晶粒尺寸变化的相同趋势,适当的初始 SFE 值对于调整 TRIP 效应的晶粒尺寸依赖性非常重要。此外,超高强度归因于高体积分数的α΄-马氏体以及高硅含量导致的马氏体相的高强度。因此,要获得强度高但韧性好的 HEA,建议采用高硅含量,以受益于马氏体相的固溶强化;需要专门设计的化学成分,以获得高体积分数的 α΄-马氏体;SFE 应在理想范围内,以调整马氏体相变的动力学。
Programmable mechanical responses of a hybrid star-rhombus honeycomb based on digital design method
Shun Wang, Hai-Tao Liu, Guang-Bin Cai
doi:10.1016/j.tws.2024.112399
基于数字设计方法的混合星形蜂窝可编程力学响应
Hybrid honeycombs with programmable mechanical responses have received widespread attention due to their multifunctionality and superior mechanical properties. To improve the tunability of the hybrid honeycomb, a hybrid star-rhombus honeycomb (HSRH) is designed using a digital design method. Different coding strategies are obtained by programming the distribution position of the rhombic structure inside the star-shaped honeycomb. HSRH with different coding strategies are designed by coding “0” (unreinforced structure) and “1” (reinforced structure). The compressive stress, Poisson's ratio and energy absorption of HSRH are investigated by experiments and numerical simulations. The results show that HSRH produces ordered deformation in compression with multi-plateau characteristics. HSRH has superior energy absorption in the X direction than in the Y direction. The specific energy absorption can be regulated between 2.41 - 5.02 J/g and 1.57 - 4.29 J/g in the X and Y directions, respectively. HSRH with unidirectional and bidirectional filling strategies exhibit a double-plateau feature in the X and Y directions, while the HSRH with hierarchical filling strategies has a three-plateau feature in the X direction. The filling ratio plays a decisive role in the energy absorption of honeycomb and has a positive correlation with the energy absorption properties. Furthermore, diverse deformation modes can be customized by introducing pattern-coding strategies. The codable deformation mode and programmable energy absorption of the HSRH are achieved by controlling the filling ratio and coding strategy (i.e., coding the number and location of embedded rhombic structures). This study provides a digital method for the design of programmable hybrid honeycombs and facilitates their application in multi-tasking energy absorbers.
具有可编程力学响应的混合蜂窝由于其多功能性和优越的力学性能而受到广泛关注。为了提高混合蜂窝的可调性,采用数字化设计方法设计了混合星形蜂窝。通过对星形蜂窝内部菱形结构的分布位置进行编程,得到了不同的编码策略。通过编码“0”(未加筋结构)和“1”(加筋结构)设计不同编码策略的HSRH。通过实验和数值模拟研究了复合材料的压应力、泊松比和能量吸收特性。结果表明:高强度压缩变形产生有序的压缩变形,具有多平台特征;HSRH在X方向上的能量吸收优于Y方向。X、Y方向的比能吸收分别可调节在2.41 ~ 5.02 J/g和1.57 ~ 4.29 J/g之间。单向和双向填充策略的HSRH在X和Y方向上表现为双平台特征,而分层填充策略的HSRH在X方向上表现为三平台特征。填充率对蜂窝吸能起决定性作用,与蜂窝吸能性能呈正相关。此外,通过引入模式编码策略,可以定制多种变形模式。通过控制填充率和编码策略(即对嵌入菱形结构的数量和位置进行编码),实现了HSRH的可编码变形模式和可编程吸能。该研究为可编程混合蜂窝的数字化设计提供了一种方法,促进了可编程混合蜂窝在多任务吸能器中的应用。
Anisotropic mechanics of cell-elongated structures: Finite element study based on a 3D cellular model
Shaohua Wang, Yudong Zhu, Jilin Yu, Liu Wang, Zhijun Zheng
doi:10.1016/j.tws.2024.112405
细胞细长结构的各向异性力学:基于三维细胞模型的有限元研究
Cell-elongated structures present designable anisotropic behaviors by controlling the ratio and angle of elongation, but the relationship between geometric anisotropy and mechanical anisotropy remains poorly understood. In this study, a construction method based on the 3D Voronoi technique is employed to generate cell-elongated structures with different elongation ratios and angles, and their anisotropic compression behaviors are investigated using a 3D cellular model. The stress–strain curves can be categorized into four stages, including elasticity, initial collapse followed by strain-softening, plateau, and densification, which are accurately described by a statistical constitutive model. Our finding reveals that the mechanical properties and deformation modes of the cell-elongated structures are significantly influenced by the anisotropic angle. At an anisotropic angle of 0°, randomly distributed collapse bands due to shell buckling interact with each other during compression, enhancing the load-carrying and energy-absorbing capacities. Conversely, at 90°, the cells deform primarily through a stable bending mode, leading to reduced stress and a lower Poisson’s ratio. At 45°, collapse bands appear on both sides of the sample with rotation and buckling being the dominant deformation mode, resulting in a sandwich-like structure featuring an uncollapsed central zone due to a combined compression-shear stress state. Compared with the isotropic foam, the structure elongated in thickness direction exhibits a notable increase in impact resistance under a spherical bullet. This work demonstrates the potential to engineer anisotropic cellular materials with tailored mechanical properties and deformation modes through strategic geometric anisotropy design.
胞状伸长结构通过控制伸长比和伸长角表现出可设计的各向异性行为,但几何各向异性与力学各向异性之间的关系尚不清楚。本研究采用基于3D Voronoi技术的构建方法,生成不同伸长比和角度的细胞伸长结构,并利用三维细胞模型研究其各向异性压缩行为。应力-应变曲线可划分为弹性阶段、初始崩溃阶段、应变软化阶段、平台阶段和致密化阶段,并可通过统计本构模型进行准确描述。结果表明,各向异性角对胞状细长结构的力学性能和变形模式有显著影响。在各向异性角度为0°时,随机分布的壳体屈曲坍塌带在压缩过程中相互作用,增强了壳体的承载和吸能能力。相反,在90°时,细胞主要通过稳定的弯曲模式变形,导致应力减小和泊松比降低。在45°时,试样两侧出现了以旋转和屈曲为主的崩塌带,由于压剪复合应力状态,形成了一个中心区未崩塌的三明治状结构。与各向同性泡沫材料相比,在厚度方向上拉长的结构在球形子弹作用下的抗冲击性能显著提高。这项工作展示了通过战略性几何各向异性设计来设计具有定制机械性能和变形模式的各向异性细胞材料的潜力。
Simulating the effects of geometric imperfections on the buckling of axially compressed cylindrical shells through reducing localized stiffness
Wenguang Gu, Haigui Fan, Yihang Hou
doi:10.1016/j.tws.2024.112410
通过降低局部刚度,模拟几何缺陷对轴向压缩圆柱壳屈曲的影响
Thin-walled cylindrical shells are prone to buckling under axial compression. The load-carrying capacity of the shells can thus be significantly reduced. It's well known that the buckling loads of axially compressed cylindrical shells are quite sensitive to the initial geometric imperfections. Even though the magnitudes of these imperfections are relatively small, the corresponding buckling loads can be significantly reduced compared to the perfect shells. In this paper, the effects of geometric imperfections on the buckling loads are equivalently simulated by reducing localized stiffness of the cylindrical shells. Firstly, the method for simulating the effects of geometric imperfections on the buckling loads of cylindrical shells is introduced in detail. Then, the proposed method is used to simulate the effects of single dimple imperfection and multiple dimple imperfections on the buckling loads of cylindrical shells. Results show that the buckling loads and load-displacement curves of the shells with single and multiple dimple imperfections can both be well simulated by the localized stiffness reduction method. Furthermore, the measured geometric imperfections from manufactured cylindrical shells are investigated. The numerical results simulated by the proposed method are also verified by the shell models with real measured geometric imperfections and the experimental results from the literature. The applicability and reliability of the proposed equivalent method in dealing with complex imperfection configurations can thus be validated. Results show that the proposed equivalent method is suitable for simulating various geometric imperfections of the cylindrical shells. It is promising to be applied as an efficient tool to quantify the imperfection sensitivity of buckling loads and provide a new solution for buckling analysis of cylindrical shells.
薄壁圆柱壳在轴向压缩下容易发生屈曲。因此,壳体的承载能力可以大大降低。众所周知,轴向压缩圆柱壳的屈曲载荷对初始几何缺陷非常敏感。尽管这些缺陷的大小相对较小,但与完美壳相比,相应的屈曲载荷可以显著降低。本文通过降低圆柱壳的局部刚度,等效模拟了几何缺陷对屈曲载荷的影响。首先,详细介绍了几何缺陷对圆柱壳屈曲载荷影响的模拟方法。然后,利用该方法模拟了单韧窝缺陷和多韧窝缺陷对圆柱壳屈曲载荷的影响。结果表明,采用局部刚度折减方法可以较好地模拟单个和多个韧窝缺陷壳的屈曲载荷和荷载-位移曲线。此外,还研究了所测圆柱壳的几何缺陷。本文方法的数值模拟结果也得到了实际测量几何缺陷壳模型和文献实验结果的验证。从而验证了所提出的等效方法在处理复杂缺陷构型时的适用性和可靠性。结果表明,所提出的等效方法适用于模拟圆柱壳的各种几何缺陷。它有望作为一种有效的工具来量化屈曲载荷的缺陷灵敏度,并为圆柱壳的屈曲分析提供一种新的解决方案。
In-plane mechanical behavior design of triangular gradient rib honeycombs
Guangxiang Wang, Fuyun Liu, Xiaolin Deng
doi:10.1016/j.tws.2024.112415
三角形梯度肋蜂窝的面内力学性能设计
Two types of triangular gradient rib honeycombs (Triangular gradient rib honeycomb-Type Z-AXBYs) were designed and proposed in this paper. A finite element numerical model was constructed using Abaqus/Explicit, with model accuracy verified, and a series of studies were conducted. Firstly, the mechanical properties of TCH, TGH, and two types of TGRH-Type Z-AXBYs under axial impact were analyzed. Results showed that the specific energy absorption (SEA) of TGH improved by 101.27% compared to TCH; TGRH-Type I-170°-AXBYs SEA improved by up to 77.21% compared to TGH; TGRH-Type II-180°-AXBYs SEA improved by up to 63.84% compared to TGH. Adding a layer with a larger angle at the bottom of the honeycomb effectively improved the impact resistance and energy absorption of the structure. The mechanical properties of two types of TGRH-Type Z-θ-AXBYs with different layers were studied, showing that TGRH-Type I-θ-AXBYs had the best mechanical properties. TGRH-Type I-θ-AXBYs SEA improved by a maximum of 23.57% compared to TGRH-Type II-θ-AXBYs and by a minimum of 13.71%. TGRH-Type I-θ-AXBYs SEA improved by a maximum of 74.95% and a minimum of 12.88% compared to TGRH-Type I-θ-6X. Finally, the effects of wall thickness and velocity on the two types of TGRH-Type Z-AXBYs were analyzed. Properly increasing the wall thickness effectively improved the impact resistance of the structure. This paper provides a feasible reference for introducing a gradient ribbed plate design into triangular honeycombs to enhance their in-plane mechanical properties.
本文设计并提出了两种三角形梯度肋蜂窝(Z-AXBYs型三角形梯度肋蜂窝)。利用Abaqus/Explicit软件建立了有限元数值模型,验证了模型的精度,并进行了一系列研究。首先,分析了TCH、TGH和两种tgrh型Z-AXBYs在轴向冲击下的力学性能。结果表明:TGH比能量吸收(SEA)比TCH提高101.27%;与TGH相比,TGRH-Type I-170°-AXBYs SEA提高了77.21%;与TGH相比,TGRH-Type II-180°-AXBYs SEA提高了63.84%。在蜂窝底部添加角度较大的层,有效提高了结构的抗冲击性和吸能性。对两种不同层数的tgrh - Z-θ-AXBYs的力学性能进行了研究,结果表明,tgrh - I-θ-AXBYs的力学性能最好。与tgrh - II型-θ-AXBYs相比,tgrh - I型-θ-AXBYs的SEA改善幅度最大为23.57%,最小为13.71%。与tgrh - I-θ-6X型相比,tgrh - I-θ-AXBYs的SEA改善幅度最大为74.95%,最小为12.88%。最后,分析了壁厚和速度对两种tgrh型Z-AXBYs的影响。适当增加壁厚可有效提高结构的抗冲击性能。本文为在三角蜂窝结构中引入梯度肋板设计以提高其面内力学性能提供了可行的参考。
Study on the preparation and mechanical behavior of carbon fiber reinforced aluminum matrix composites stator blade
Yunfeng Bai, Jiming Zhou, Kangdi Zhong, Xinkai Wang, Lehua Qi
doi:10.1016/j.tws.2024.112418
碳纤维增强铝基复合材料定子叶片的制备及其力学性能研究
The advancement of high-performance stator blades stands as a critical avenue for enhancing the efficacy of aero engines. This study aims to prepare carbon fiber reinforced aluminum matrix (CF/Al) composite stator blades with high-quality shapes and properties, optimize the lay-up design using Fibersim software, and investigate the effect of extrusion temperature on the forming quality. The mechanical properties and damage behavior were systematically analyzed by tensile, compression, and interlaminar shear tests. In addition, the vibration mode simulation reveals the force state under the 1st to 8th-order vibration modes. Results indicate that the [0°/+45°/0°/-45°/90°/-45°/0°/+45°/0°] lay-up parameters were optimal, achieving excellent shape and performance of curved preforms after curing. Composite blades fabricated at an extrusion temperature of 680°C exhibited clear contours, consistent dimensions, and no macro defects. SEM and EDS analyses showed uniform impregnation in all regions of the blade, high density, and good densification. Compared with the matrix alloy, the tensile strength of the composite blade was improved by 64.94%, the compressive strength by 35.7%, and the interlayer shear strength was as low as 72.6 MPa. The vibration mode simulation verified the applicability of the blade in the first-order vibration mode, which provides strong support for the application of composite materials in the aerospace field.
高性能静叶的发展是提高航空发动机效能的重要途径。本研究旨在制备具有高质量形状和性能的碳纤维增强铝基(CF/Al)复合静叶,并利用Fibersim软件优化铺层设计,研究挤压温度对成形质量的影响。通过拉伸、压缩和层间剪切试验系统地分析了材料的力学性能和损伤行为。此外,振动模态仿真揭示了1 ~ 8阶振动模态下的受力状态。结果表明:[0°/+45°/0°/-45°/90°/-45°/0°/+45°/0°]铺层参数最优,可获得良好的弯曲预制件形状和性能。在680℃的挤压温度下制备的复合叶片轮廓清晰,尺寸一致,无宏观缺陷。SEM和EDS分析表明,叶片各区域浸渍均匀,密度高,致密化良好。与基体合金相比,复合叶片抗拉强度提高了64.94%,抗压强度提高了35.7%,层间抗剪强度低至72.6 MPa。振动模态仿真验证了叶片在一阶振动模态下的适用性,为复合材料在航空航天领域的应用提供了有力支撑。
Omni-directional wavenumber dictionary modified imaging method for orthotropic composites damage detection using ultrasonic guided waves
Jikang Yue, Xiaobin Hong, Bin Cui, Ruimou Cai, Guochen Xu, Weiguo Chen
doi:10.1016/j.tws.2024.112419
正交异性复合材料超声导波损伤检测的全向波数字典修正成像方法
The sparse reconstruction imaging method is promising for detecting damage in isotropic and quasi-isotropic materials. However, its effectiveness relies on an accurate dictionary. When applied to orthotropic materials without accounting for wavenumber directionality, the accuracy of the dictionary degrades, leading to inaccurate damage localization. To address this limitation, this paper presents an omnidirectional wavenumber dictionary modified imaging method for orthotropic composites damage detection. The omni-directional wavenumber dispersion curve of ultrasonic guided waves is calculated numerically by converting of elastic stiffness coefficient of orthotropic composites at various propagation angles. A modified propagation model, informed by the omni-directional wavenumber dispersion curve, enhances the precision of the acoustic field dictionary. Utilizing a coherent matched field processor, the method compares the scattered signal's envelope with the acoustic field dictionary's envelope to generate an ambiguity function, which in turn forms a damage image. Simulation and experimental results confirm the method's superiority in resolving damage localization inaccuracies and artifacts typically associated with orthotropic composites. The proposed method exhibits enhanced signal-to-noise ratio and lower positioning error, facilitating precise multi-damage detection in orthotropic composites compared to existing methods.
稀疏重建成像方法在各向同性和准各向同性材料损伤检测中具有广阔的应用前景。然而,它的有效性依赖于一个准确的字典。当应用于正交异性材料而不考虑波数方向性时,字典的精度会降低,导致不准确的损伤定位。针对这一缺陷,本文提出了一种全向波数字典修正的正交各向异性复合材料损伤检测成像方法。通过变换正交异性复合材料在不同传播角下的弹性刚度系数,数值计算了超声导波的全向波数色散曲线。基于全向波数色散曲线的改进传播模型提高了声场字典的精度。该方法利用相干匹配场处理器,将散射信号的包络与声场字典的包络进行比较,生成模糊函数,从而形成损伤图像。仿真和实验结果证实了该方法在解决正交异性复合材料损伤定位误差和典型伪像方面的优越性。与现有方法相比,该方法具有更高的信噪比和更小的定位误差,可实现正交异性复合材料多损伤的精确检测。