冰球和钨珠非正冲击下T800-CFRP层合板损伤特性的研究

通过试验和仿真相结合的方法研究了T800碳纤维增强复合材料(CFRP)层合板在冰球和钨珠非正冲击作用下的损伤特性。首先开展了冰球和钨珠在给定工况下高速撞击T800-CFRP层合板试验,以此对仿真模型的有效性进行验证;然后讨论了T800-CFRP层合板在两种冲击体以不同冲击能量与冲击角度作用下的损伤特性及其差异性。研究表明:钨珠在冲击能量较低时就能对层合板造成穿孔损伤,但随着冲击能量增大层合板的损伤程度呈下降趋势;冰球对层合板造成损伤的冲击能量阈值与钨珠的相比要高很多,且随着冲击能量的增加损伤程度明显加剧;钨珠在冲击角度为45°和60°时造成的损伤与正冲击的情况相比要更加严重,而冲击角度为30°时造成的损伤却小于正冲击的情况;冰球冲击时,层合板的损伤程度随冲击角度的增加而减小。该研究有助于深化对T800-CFRP层合板在冲击载荷作用下的损伤与破坏行为的认识,具有重要的科学意义和工程应用价值。

喷丸强化对预变形CP800复相钢疲劳性能的影响

喷丸强化可以提高CP800复相钢的抗疲劳性能.采用低(0.15 mmA)、中(0.3 mmA)、高(0.5 mmA)3种喷丸强度对5%预拉伸变形后的CP800复相钢进行表面喷丸处理,研究了喷丸后材料的表面形貌和表面残余应力,并通过拉压疲劳试验分析了疲劳断口.研究发现:2 mm板厚的CP800复相钢更适合采用低喷丸强度,疲劳寿命约为未喷丸试样的3倍;疲劳寿命的提升归因于表层发生塑性变形、位错密度提高,且残余压应力可抑制裂纹萌生;喷丸后材料表面粗糙度增大;喷丸强度过高易造成表面缺陷增多,尤其在高喷丸强度下,试样表面会出现分层损伤现象,对疲劳性能有不利影响.

国产T800级碳纤维本征特性研究进展

综述了近年来对国产T800级碳纤维本征特性的相关研究进展,包括纤维的力学性能、微观物理特性和表面化学特性等,并与东丽T800碳纤维对比,指出了国产T800级碳纤维性能上存在的一些问题。

800 V充电平台中SiC材料的应用及发展趋势

SiC功率器件具有优异的性能,已经成为高端新能源汽车的核心部件,并随着应用成本的降低在逐步取代传统的Si基器件。然而,SiC单晶生长的参数可控性差、成本高、扩径难度大,它的市场渗透受到制约。当前对于SiC材料的投资非常火热,国内也有大量产业项目开展,但是实际投产却相对较少,半导体材料行业准入门槛较高,也需警惕重复建设的风险。山西烁科晶体有限公司实现了6英寸(1英寸=25.4 mm)SiC衬底产业化,并推出了8英寸产品,计划在十四五期间内将年产能扩充至150万片以满足市场巨大的需求,同时不断提升产品的良率及性能,助力第三代半导体行业的发展,在实现“碳达峰碳中和”的目标道路上贡献力量。

基于刀具结构的T800-CFRP铣削刀具磨损抑制和加工质量优化

碳纤维增强树脂基复合材料(Carbon Fiber Reinforced Polymer,CFRP)因其比强度高、抗疲劳和耐腐蚀等优异性能在航空航天领域得到了广泛应用。然而,CFRP材料的非均质性和各向异性使其加工过程与传统金属相比更为复杂,容易产生表面缺陷,且由于碳纤维以及碳纤维粉末的高硬度,使得刀具磨损剧烈,加工效率低。为此,以PCD刀具铣削T800-CFRP多向层合板为研究对象,综合仿真分析和铣削试验,从刀具磨损、已加工表面粗糙度和毛刺因子等方面研究分析了铣削该类材料时的刀具结构对刀具寿命及加工表面质量的影响。基于刀具磨损和表面质量试验结果,以刀具后刀面磨损带宽、表面粗糙度、毛刺因子为优化目标,建立了后刀面磨损带宽VB、表面粗糙度Sa、毛刺因子Fb关于刀具齿数、前角和后角的映射关系模型和综合评价模型,进而通过鲸鱼优化算法,获得了最优的刀具结构参数,并通过试验验证,刀具磨损减小了16.95%,表面粗糙度减小了32.41%,毛刺因子减小了52.93%。

高温暴晒和火灾服役条件下高强钢DP800的力学性能变化规律

为了揭示极端高温暴晒服役条件和火灾服役条件下DP800钢的力学性能,采用“加热-保温-空冷”与“加热-保温-水冷”方法分别模拟两种高温服役条件,通过显微组织观测和静载拉伸试验研究高温服役后DP800钢的微观组织形貌特征和力学性能变化规律。结果表明:不同高温空冷条件下(室温~200℃),DP800钢的组织均为铁素体和分布在其晶界上的岛状马氏体,随着服役温度的升高和时间的增加,其力学性能得到明显改善;高温水冷对DP800钢的微观组织和力学性能影响显著,随着服役温度的不断升高,两种保温时间下DP800钢的微观组织均经历了“马氏体铁素体化(300~700℃)→铁素体+马氏体双相组织(700~900℃)”的变化规律,其抗拉强度和屈服强度均呈现出“不断下降(300~700℃)→持续增大(700~850℃)→再次下降(850~900℃)”的变化规律。采用非线性回归法,构建了服役时间不超过60 min时高温水冷条件下DP800钢的抗拉强度、屈服强度随服役温度变化的经验预测模型,最大预测误差仅为7.88%,该模型可为高温服役后DP800钢力学性能变化评价提供理论参考。

Goodrive800变频器在高线主轧机的应用

轧钢主传动是轧线上轧机及大型相关设备的电动机驱动系统,是生产线上的关键构成,其主要特点是功率大、动作指标要求严格扥。在轧钢生产过程中,要求电机的调速范围较宽、转矩动态响应高、调速性能好,并对轧制时的冲击负荷,要求过载倍数高。西门子变频器在冶金行业应用广泛,并有着举足轻重的地位。但由于其存在一定的缺陷,现阶段西门子变频器也面临更新换代,因此传动变频器国产化势在必行。文章主要介绍国产变频器无缝替换西门子系列变频器在高线主轧机传动负载的应用。

Experimental Study on Vortex-Induced Vibration of Rough Risers Coupling with Interference Effect in Tandem Arrangement

In order to study the response law of vortex-induced vibration(VIV)of marine risers under the combined action of roughness and interference effects,and to reveal the coupling mechanism of roughness and interference effects on the riser,a VIV experiment of rough risers in tandem arrangement was conducted in a wave−current combined flume.The experiment characterized the risers’roughness by arranging different specifications of attachments on the surface of the risers.Three rough risers with different roughness and smooth risers were arranged in tandem arrangement,with the rough risers arranged downstream.The experimental results indicate that the suppression of the attachments on the downstream risers’vibration are more significant both in the CF and IL directions as the reduced velocity increases.For the downstream riser,the amplitude response of rough riser is more significantly weakened compared with the smooth one at high reduced velocity.For the upstream risers,changes in the roughness and spacing ratio have an impact on their‘lock-in’region.When the roughness of downstream risers is relatively large(0.1300)and the spacing between risers is small(S/D=4.0),the reduced velocity range of‘lock-in’region in the CF direction of upstream risers is obviously expanded,and the displacement in the‘lock-in’region is severer.

Shear behavior and off-fault damage of saw-cut smooth and tension-induced rough joints in granite

The damage of rock joints or fractures upon shear includes the surface damage occurring at the contact asperities and the damage beneath the shear surface within the host rock.The latter is commonly known as off-fault damage and has been much less investigated than the surface damage.The main contribution of this study is to compare the results of direct shear tests conducted on saw-cut planar joints and tension-induced rough granite joints under normal stresses ranging from 1 MPa to 50 MPa.The shear-induced off-fault damages are quantified and compared with the optical microscope observation.Our results clearly show that the planar joints slip stably under all the normal stresses except under 50 MPa,where some local fractures and regular stick-slip occur towards the end of the test.Both post-peak stress drop and stick-slip occur for all the rough joints.The residual shear strength envelopes for the rough joints and the peak shear strength envelope for the planar joints almost overlap.The root mean square(RMS)of asperity height for the rough joints decreases while it increases for the planar joint after shear,and a larger normal stress usually leads to a more significant decrease or increase in RMS.Besides,the extent of off-fault damage(or damage zone)increases with normal stress for both planar and rough joints,and it is restricted to a very thin layer with limited micro-cracks beneath the planar joint surface.In comparison,the thickness of the damage zone for the rough joints is about an order of magnitude larger than that of the planar joints,and the coalesced micro-cracks are generally inclined to the shear direction with acute angles.The findings obtained in this study contribute to a better understanding on the frictional behavior and damage characteristics of rock joints or fractures with different roughness.

Experimental Study on Vortex-Induced Vibration of Rough Risers with Coupling Interference Effect Under Side-by-Side Arrangement

A vortex-induced vibration(VIV)experiment of rough risers with coupling interference effect under a side-by-side arrangement was carried out in a wave-current combined flume.The roughness of the riser was characterized by arranging different specifications of surface attachments on the surface of the riser.Rough risers with three different roughnesses were arranged side by side with smooth risers to explore the VIV response of the riser under the combined action of roughness and interference effect,and to reveal the coupling mechanism between roughness and interference effect.The experimental results show that,compared with that of a smooth riser,the VIV of a rough riser under the coupling interference effect has a wider"lock-in"region,and the displacement decreases more significantly at a high reduced velocity,which is more likely to excite higher-order modes and frequency responses.In addition,the displacement response and frequency response of the smooth riser are not significantly affected by wake interference from the rough riser,which is caused by the decrease of the wake region due to the delay of the boundary layer separation point of the rough riser.

2250热轧产线800 MPa级汽车厢体钢的开发

介绍了某钢厂2250热轧产线800 MPa级汽车厢体钢的开发过程及关键技术。通过优化合金设计、调整热轧工艺参数及特殊的两段冷却控制,成功研制出满足汽车厢体结构强度要求的800MPa级高强度钢。详细阐述了合金元素的选择依据及其对钢材性能的影响,分析了热轧过程中温度、冷却模式及冷却速度对组织演变和力学性能的作用机制。研究结果表明,所开发的高强度钢具有良好的强度、韧性及成型性,能够满足汽车轻量化与安全性的双重需求。

Complex Decision Modeling Framework with Fairly Operators and Quaternion Numbers under Intuitionistic Fuzzy Rough Context

The main goal of informal computing is to overcome the limitations of hypersensitivity to defects and uncertainty while maintaining a balance between high accuracy,accessibility,and cost-effectiveness.This paper investigates the potential applications of intuitionistic fuzzy sets(IFS)with rough sets in the context of sparse data.When it comes to capture uncertain information emanating fromboth upper and lower approximations,these intuitionistic fuzzy rough numbers(IFRNs)are superior to intuitionistic fuzzy sets and pythagorean fuzzy sets,respectively.We use rough sets in conjunction with IFSs to develop several fairly aggregation operators and analyze their underlying properties.We present numerous impartial laws that incorporate the idea of proportionate dispersion in order to ensure that the membership and non-membership activities of IFRNs are treated equally within these principles.These operations lead to the development of the intuitionistic fuzzy rough weighted fairly aggregation operator(IFRWFA)and intuitionistic fuzzy rough ordered weighted fairly aggregation operator(IFRFOWA).These operators successfully adjust to membership and non-membership categories with fairness and subtlety.We highlight the unique qualities of these suggested aggregation operators and investigate their use in the multiattribute decision-making field.We use the intuitionistic fuzzy rough environment’s architecture to create a novel strategy in situation involving several decision-makers and non-weighted data.Additionally,we developed a novel technique by combining the IFSs with quaternion numbers.We establish a unique connection between alternatives and qualities by using intuitionistic fuzzy quaternion numbers(IFQNs).With the help of this framework,we can simulate uncertainty in real-world situations and address a number of decision-making problems.Using the examples we have released,we offer a sophisticated and systematically constructed illustrative scenario that is intricately woven with the complexity ofmedical evaluation in order to thoroughly assess the relevance and efficacy of the suggested methodology.

高分散性活性剂SA-800在胎面胶中的应用

研究高分散性活性剂SA-800(简称SA-800)等氧化锌含量(简称等锌)或减氧化锌含量(简称减锌)替代普通氧化锌在胎面胶中的应用。结果表明:SA-800等锌替代普通氧化锌时,胎面胶的焦烧时间和正硫化时间延长,加工安全性好,其他性能基本相当,可在丁苯橡胶/顺丁橡胶/白炭黑胎面胶和天然橡胶/炭黑胎面胶中替代普通氧化锌;SA-800减锌替代普通氧化锌时,胎面胶的焦烧时间和正硫化时间与等锌替代时相比略有缩短,仍长于普通氧化锌胎面胶,其他性能变化不大,且与普通氧化锌胎面胶基本相当。使用SA-800可实现锌减量的目的。

Roughness characterization and shearing dislocation failure for rock-backfill interface

Shearing dislocation is a common failure type for rock–backfill interfaces because of backfill sedimentation and rock strata movement in backfill mining goaf.This paper designed a test method for rock–backfill shearing dislocation.Using digital image techno-logy and three-dimensional(3D)laser morphology scanning techniques,a set of 3D models with rough joint surfaces was established.Further,the mechanical behavior of rock–backfill shearing dislocation was investigated using a direct shear test.The effects of interface roughness on the shear–displacement curve and failure characteristics of rock–backfill specimens were considered.The 3D fractal dimen-sion,profile line joint roughness coefficient(JRC),profile line two-dimensional fractal dimension,and the surface curvature of the frac-tures were obtained.The correlation characterization of surface roughness was then analyzed,and the shear strength could be measured and calculated using JRC.The results showed the following:there were three failure threshold value points in rock–backfill shearing dis-location:30%–50%displacement before the peak,70%–90%displacement before the peak,and 100%displacement before the peak to post-peak,which could be a sign for rock–backfill shearing dislocation failure.The surface JRC could be used to judge the rock–backfill shearing dislocation failure,including post-peak sliding,uniform variations,and gradient change,corresponding to rock–backfill disloca-tion failure on the field site.The research reveals the damage mechanism for rock–backfill complexes based on the free joint surface,fills the gap of existing shearing theoretical systems for isomerism complexes,and provides a theoretical basis for the prevention and control of possible disasters in backfill mining.

Maximal operators of pseudo-differential operators with rough symbols

Consider a pseudo-differential operator T_(a)f(x)=∫_(R^(n))e^(ix,ζ)a(x,ζ)f(ζ)dζwhere the symbol a is in the rough Hormander class L^(∞)S_(ρ)^(m)with m∈R andρ∈[0,1].In this note,when 1≤p≤2,if n(ρ-1)/p and a∈L^(∞)S_(ρ)^(m),then for any f∈S(R^(n))and x∈R^(n),we prove that M(T_(a)f)(x)≤C(M(|f|^(p))(x))^(1/p) where M is the Hardy-Littlewood maximal operator.Our theorem improves the known results and the bound on m is sharp,in the sense that n(ρ-1)/p can not be replaced by a larger constant.

Influence of Surface Ice Roughness on the Aerodynamic Performance of Wind Turbines

The focus of this research was on the equivalent particle roughness height correction required to account for the presence of ice when determining the performances of wind turbines.In particular,two icing processes(frost ice and clear ice)were examined by combining the FENSAP-ICE and FLUENT analysis tools.The ice type on the blade surfaces was predicted by using a multi-time step method.Accordingly,the influence of variations in icing shape and ice surface roughness on the aerodynamic performance of blades during frost ice formation or clear ice formation was investigated.The results indicate that differences in blade surface roughness and heat flux lead to disparities in both ice formation rate and shape between frost ice and clear ice.Clear ice has a greater impact on aerodynamics compared to frost ice,while frost ice is significantly influenced by the roughness of its icy surface.

RB-DEM Modeling and Simulation of Non-Persisting Rough Open Joints Based on the IFS-Enhanced Method

When the geological environment of rock masses is disturbed,numerous non-persisting open joints can appear within it.It is crucial to investigate the effect of open joints on the mechanical properties of rock mass.However,it has been challenging to generate realistic open joints in traditional experimental tests and numerical simulations.This paper presents a novel solution to solve the problem.By utilizing the stochastic distribution of joints and an enhanced-fractal interpolation system(IFS)method,rough curves with any orientation can be generated.The Douglas-Peucker algorithm is then applied to simplify these curves by removing unnecessary points while preserving their fundamental shape.Subsequently,open joints are created by connecting points that move to both sides of rough curves based on the aperture distribution.Mesh modeling is performed to construct the final mesh model.Finally,the RB-DEM method is applied to transform the mesh model into a discrete element model containing geometric information about these open joints.Furthermore,this study explores the impacts of rough open joint orientation,aperture,and number on rock fracture mechanics.This method provides a realistic and effective approach for modeling and simulating these non-persisting open joints.

High-order Bragg forward scattering and frequency shift of low-frequency underwater acoustic field by moving rough sea surface

Acoustic scattering modulation caused by an undulating sea surface on the space-time dimension seriously affects underwater detection and target recognition.Herein,underwater acoustic scattering modulation from a moving rough sea surface is studied based on integral equation and parabolic equation.And with the principles of grating and constructive interference,the mechanism of this acoustic scattering modulation is explained.The periodicity of the interference of moving rough sea surface will lead to the interference of the scattering field at a series of discrete angles,which will form comb-like and frequency-shift characteristics on the intensity and the frequency spectrum of the acoustic scattering field,respectively,which is a high-order Bragg scattering phenomenon.Unlike the conventional Doppler effect,the frequency shifts of the Bragg scattering phenomenon are multiples of the undulating sea surface frequency and are independent of the incident sound wave frequency.Therefore,even if a low-frequency underwater acoustic field is incident,it will produce obvious frequency shifts.Moreover,under the action of ideal sinusoidal waves,swells,fully grown wind waves,unsteady wind waves,or mixed waves,different moving rough sea surfaces create different acoustic scattering processes and possess different frequency shift characteristics.For the swell wave,which tends to be a single harmonic wave,the moving rough sea surface produces more obvious high-order scattering and frequency shifts.The same phenomena are observed on the sea surface under fully grown wind waves,however,the frequency shift slightly offsets the multiple peak frequencies of the wind wave spectrum.Comparing with the swell and fully-grown wind waves,the acoustic scattering and frequency shift are not obvious for the sea surface under unsteady wind waves.

On Multi-Granulation Rough Sets with Its Applications

Recently,much interest has been given tomulti-granulation rough sets (MGRS), and various types ofMGRSmodelshave been developed from different viewpoints. In this paper, we introduce two techniques for the classificationof MGRS. Firstly, we generate multi-topologies from multi-relations defined in the universe. Hence, a novelapproximation space is established by leveraging the underlying topological structure. The characteristics of thenewly proposed approximation space are discussed.We introduce an algorithmfor the reduction ofmulti-relations.Secondly, a new approach for the classification ofMGRS based on neighborhood concepts is introduced. Finally, areal-life application from medical records is introduced via our approach to the classification of MGRS.

Characteristics of proppant transport and placement within rough hydraulic fractures

A three-dimensional reconstruction of rough fracture surfaces of hydraulically fractured rock outcrops is carried out by casting process,a large-scale experimental setup for visualizing rough fractures is built to perform proppant transport experiments.The typical characteristics of proppant transport and placement in rough fractures and its intrinsic mechanisms are investigated,and the influences of fracture inclination,fracture width and fracturing fluid viscosity on proppant transport and placement in rough fractures are analyzed.The results show that the rough fractures cause variations in the shape of the flow channel and the fluid flow pattern,resulting in the bridging buildup during proppant transport to form unfilled zone,the emergence of multiple complex flow patterns such as channeling,reverse flow and bypassing of sand-carrying fluid,and the influence on the stability of the sand dune.The proppant has a higher placement rate in inclined rough fractures,with a maximum increase of 22.16 percentage points in the experiments compared to vertical fractures,but exhibits poor stability of the sand dune.Reduced fracture width aggravates the bridging of proppant and induces higher pumping pressure.Increasing the viscosity of the fracturing fluid can weaken the proppant bridging phenomenon caused by the rough fractures.