“力学动态”文摘2013年第24卷第6期

    中国科学院和中国工程院2013年院士增选工作均已顺利结束。
    根据《中国科学院院士章程》和《中国科学院院士增选工作实施细则》的规定，2013年中国科学院选举产生了53名中国科学院院士和9名中国科学院外籍院士。
    在中国工程院主席团领导下，各学部严格按照《中国工程院章程》和《中国工程院院士增选工作实施办法》的规定，坚持公平、公正的原则，通过科学、严谨的评审程序，选举产生了51名新院士。
    北京大学陈十一、方岱宁教授分别当选中国科学院数学物理学部和技术科学部院士。

附件：
1、2013年中国科学院院士增选和外籍院士选举结果

2、中国工程院2013年院士增选结果

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北京国际力学中心第一届亚太地区青年联谊会在新加坡举办

（摘自中国力学学会网站）

    2013年12月13至14日，“北京国际力学中心第一届亚太地区青年联谊会”在新加坡举办，清华大学冯西桥教授（北京国际力学中心秘书长）担任会议主席。来自清华大学、北京交通大学、北京航空航天大学、同济大学、复旦大学、苏州大学、西安交通大学、湖南大学、重庆大学、天津大学、昆士兰理工大学、悉尼大学、高丽大学、新加坡高性能计算研究所、香港城市大学等多家国内外大学和研究机构的40余位青年学者参加会议。
    此次活动由北京国际力学中心和中国力学学会主办，旨在推动不同国家地区青年学者之间的认识与合作，吸引和吸收亚太地区青年学者积极参与北京国际力学中心组织开展的学术交流活动。
    活动开幕式由冯西桥主持，他首先向参加联谊会的代表表示欢迎，并简要介绍了北京国际力学中心的背景：北京国际力学中心是中国力学学会在北京构建的国际力学交流平台，旨在促进亚太地区的力学学科发展。“中心”已于2010年成为国际力学联盟（IUTAM）关联所属组织，成为IUTAM继1970年在意大利设立欧洲国际力学中心之后，在全球设立的第二个国际力学中心。 “中心”自成立以来已组织开展专题研讨会、暑期学校和讲习班等学术交流活动40余次，接待客座访问教授50多位，年均参与“中心”活动的国内外学者近700人次。
    随后，联谊会安排了11个精彩的学术报告，涵盖了计算力学、生物力学、材料力学、固体力学等多个学科，不同国家地区的研究团队分享了他们近期的科研成果，进行了全面的内容阐述，大家相互交流讨论，气氛热烈。

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第三届中国磁流体力学学术研讨会在湖南湘潭召开

（摘自中国力学学会网站）

    2013年11月29-12月2日，由中国力学学会主办，湘潭大学 “科学工程计算与数值仿真”湖南省重点实验室、湘潭大学数学与计算科学学院、北京交通大学磁性液体研究所和中国科学院大学物理科学学院共同承办，北京大学工学院，北京科技大学数理学院和西安交通大学理学院共同协办的"第三届中国磁流体力学学术研讨会"在湘潭大学召开，共有70余位数学、物理、机械、能源和力学等学科领域的专家学者参加会议。
    大会开幕式在湘潭大学松涛山庄学术报告厅举行，湘潭大学“杰出青年基金”获得者黄云清副校长作为本届会议荣誉主席致辞，他介绍了湘潭大学及湘潭大学数学与计算科学学院的基本概况。本届会议主席北京交通大学“长江学者”李德才教授致开幕词，会议开幕式由湘潭大学数学与计算科学学院李明军教授主持。
    会议围绕“磁流体力学”这一共同主题开展报告和讨论。日本工程院院士Hiroshi Yamaguchi，北京交通大学“长江学者”李德才，前两届会议主席中国科学院大学 “百人计划”倪明玖，重庆大学“青年千人计划”徐立伟，上海大学“长江学者”任忠鸣，西安交通大学徐忠锋，北京科技大学特聘教授郑连存，中国科学院力学所“百人计划”刘谋斌，西安交通大学“天山学者”何银年和湘潭大学“百人计划”牛小东等10位教授作大会特邀报告，中国科学院电工所彭燕，太原科技大学王建梅，河南理工大学原保全和云南师范大学化存才等教授担任分会主席。
    最后，经学术委员会讨论，达成了如下共识：1、2014年“第四届中国磁流体力学研讨会”由上海大学牵头承办；2、选送4-5篇综述报告发表在Theoretical & Applied Mechanics Letters上；3、2015年中国力学大会“磁流体力学专题研讨会”以学生学术报告为主，按录用论文数的10%评选优秀论文，并推荐在学术期刊发表；4、同意支持积极申办“磁流体国际会议”。

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教育部：高校科研评价不再过分依赖论文

（摘自科学网）

    今后，在高校科技评价及教师评聘、收入分配中，科技项目与经费数量过分指标化、目标化，过分依赖论文、项目专利等指标的情况或将得到改变。近日，教育部官网发布《关于深化高等学校科技评价改革的意见》（以下简称《意见》）中明确提出，对高校、教师的科研评价，将实施分类评价，不搞一刀切。

■新政
>>现状
高校科技评价短视轻质

    《意见》指出，高校长期以来形成的以统一、量化为特征的科技评价机制，面对全面提高质量和创新驱动发展的时代要求，问题日益显现。
    其中，重数轻质、重形式轻内容、重短期轻长远的现象依然存在；评价指标单一化、评价标准定量化、评价方法简单化、评价结果功利化等倾向没有得到根本扭转；分类评价实施不到位，对科技成果转化、科学普及等工作激励不足；科技支撑教学和创新人才培养的导向不够；开放评价、长效评价机制不够健全。
    这些问题将严重影响高校科技工作的持续健康发展，改革任务十分紧迫。

>>改革
减少科研与利益过度挂钩

    《意见》提出，全面改革教育系统各类科技项目、人才项目和科技奖励的评审办法。提高科技奖励质量，减少数量，适当延长报奖成果的应用年限。地方教育行政部门也要对各类科技项目、人才项目和科技奖励做相应改革。
    教育部要求各高校要改变考核评价中将科技项目与经费数量过分指标化、目标化的做法。要改变在教师评聘、收入分配中过分依赖和不合理使用论文、专利、项目和经费数量等科技指标的做法，减少科技评价结果与利益分配过度关联。
    教育部要求，建立开放评价机制。基础研究以同行评价为主，大力加强国际同行评价。加强开放、多元的国内外专家数据库建设和共享。

>>评价
按不同对象实施分类评价

《意见》提出，实行分类评价，改变考核评价中将科技项目与经费数量过分指标化、目标化的做法，针对科技活动人员、创新团队、平台基地、科研项目等不同对象，按照基础研究、应用研究、技术转移、成果转化等不同工作的特点，分别建立涵盖科研诚信和学风、创新质量与贡献、科教结合支撑人才培养、科学传播与普及、机制创新与开放共享等内容，科学合理、各有侧重的评价标准。
同时，建立长效评价机制，避免频繁评价。科技活动人员的评价周期原则上不少于3年，对青年科技人员实施聘期评价，创新团队和平台基地的评价周期原则上不少于5年，根据绩效情况可减少、减免评价。加强评价结果共享，避免重复评价。

>>专家点评
改革利于遏制科研腐败

    昨天，中国教育科学研究院研究员储朝晖表示，高校科研院所存在很大的问题，很多人已经利用科研作为一种腐败的手段。教育部在此时对科研评价体系进行改革，有利于打破统一量化的评价机制，有利于科学研究。
    储朝晖说，高校科研目前最大的问题是科研评价由行政部门进行，很多行政部门并不懂科研，所以才会存在单一的量化论文数量，出现数论文的情况。一直以来，我国的评价机制是一年一评，这使得科研很自然地与领导政绩挂钩，与老师奖金挂钩。特别是此次提出的团队挂名问题，其实，很多论文、科研成果都是给领导挂名，这种“包工头”式的科研方式弊病很多。他认为，此次教育部提出不同科研方向人员的评价重点是进步，但更多的应该建立独立第三方的评价方式，解决“由谁来评”的问题。
    储朝晖认为，论文与科研经费挂钩是现在高校的普遍现象，因此才有跑项目等情况出现。真正的专业评价机制建立起来，才会对这种现象有本质的解决。此外，延长评价周期起码3年一评，他认为这项措施对功利心较强的年轻老师影响较大，对于安身立命做研究的老师则不存在负面影响。

■分类评价
    对主要从事创新性研究的科技活动人员实行代表性成果为重点的评价。
    对基础研究人员的评价以有利于潜心研究、长期积累，催生重大原创性成果为重点。对应用研究人员的评价以聚焦需求，具有自主知识产权和重大技术突破为重点。对软科学研究人员的评价以服务决策需求，形成战略研究报告，支撑思想库智囊团建设为重点。
    对主要从事技术转移、科技服务和科学普及的科技活动人员实行经济社会效益和实际贡献为重点的评价。
    鼓励高校按照国家相关规定，完善职务聘任和岗位聘用机制，面向市场和产业需求，把科技转化为现实生产力;加强协同创新，强化企业在技术创新中的主体地位;积极开展科学普及活动，提高全民科学素养;创新人才培养模式，提高创新创业人才培养质量。
    对从事技术支撑和服务的科技活动人员实行以服务质量与实际效果为重点的评价。
    鼓励高校加强职务聘任和岗位聘用的引导，提高技术支撑人员服务技能，加强自主开发仪器设备。
    对高校创新团队实行以解决重大科技问题能力与合作机制为重点的整体性评价。
    围绕团队自身建设、代表性成果、科教结合、机制文化等方面开展评价。要认可团队科技成果所有参与者的实际贡献，同时反对无实质贡献的虚假挂名。
    对高校创新平台（机构、基地）实行以综合绩效和开放共享为重点的评价。
    围绕创新质量、服务贡献、科教结合、人才队伍、机制文化等方面开展评价。鼓励创新平台深化科教结合，注重创新成果转化、技术服务和科学普及。鼓励接受国内外访问学者。科研基础设施依照规定应该开放的一律对社会开放。

>>相关新闻
    国家科技经费使用弱化论文数量指标
    昨天，在中国国际经济交流中心主办的中国经济年会上，国家发改委副主任张晓强提出，要改革国家科技经费使用的绩效评价体系，弱化发表学术论文数量、院士数量、科技成果奖数量等指标，突出发明专利授权、技术成果转化率、促进产业技术进步等方面的考核。
    张晓强表示，为提高科技资源使用效率，要改革国家对科技资源的管理体制机制，解决好多单位分蛋糕、抢课题等重复浪费的顽症，解决好科研单位与高校存在的大批高端科研装备不开放、不共享、低利用率的突出问题。“创新驱动发展战略的有效实施，从某种意义上讲，最迫切的不是增大科技投入，也不能就科技创新谈科技创新，而是要加快科技体制改革步伐，破除体制机制障碍。”张晓强说。

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学术会议

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Minisymposium on Mechanics and Physics of Soft Matter Materials

（Michigan State University, East Lansing, Michigan，June 15-20, 2014）

As part of USNCTAM2014 (17th U.S. National Congress on Theoretical & Applied Mechanics) to be held at Michigan State University, East Lansing, Michigan from June 15-20, 2014, we are organizing a Minisymposium entitled Mechanics and Physics of Soft Matter Materials within the Mechanics of Solids and Structures Technical Track. Detailed information on the conference is available at http://www.usnctam2014.org
We invite you to submit abstracts to this Minisymposium at https://www.egr.msu.edu/conference/. The extended deadline for the abstract submission is January 6, 2014.
The following selected keywords serve exemplarily as guideline for potential contributions:

            Development of physical models, experiments and numerical techniques for soft matter materials
            Modeling micromechanical mechanisms in soft matter engineered materials like polymers, foams, nonwoven fabrics, granular materials, or gels
            Modeling micromechanical mechanisms in soft matter natural materials like cells, biological tissues, or muscles
            Modeling microstructural driven large deformations in soft matter materials
            Multiphysical coupling aspects (mechanical, thermal, electrical, magnetical, chemical)
            Failure in soft matter materials
            Advanced simulation techniques at various length and time scales through finite element methods, meshfree methods, atomistic simulations, or electronic structure calculations
            Coupling of length- and time-scales through advanced homogenization techniques
            Multidisciplinary contributions focusing on applications in material systems like shape memory and conductive polymers, dielectric elastomers, or soft active structures and devices

        Minisymposium organizers: Christian Linder (Stanford), Katia Bertoldi (Harvard), Rui Huang (UT Austin), Oscar Lopez-Pamies (UIUC), and Stephan Rudykh (MIT)
　

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The 2014 International Conference on Advances in Micromechanics of Materials

（Rzeszów University of Technology, Rzeszów, Poland, 8-11 July 2014）

MICROMECH2014:
Micromechanics of materials is rapidly growing interdisciplinary field of engineering science. It is developed by specialists in solid mechanics, applied mathematics and materials science. Micromechanics studies materials that can be generally characterized as multiphase mixtures. Perhaps, the most important class of them can be described as a matrix containing various inhomogeneities, like pores, microcracks, fibers, foreign particles. Another example is given by polycrystalline aggregates (like metals), consisting of crystallites of diverse orientations. Such materials may be man-made (composites, metals, foams) and may occur in nature (cracked or porous rocks, ice, bones). The goal of micromechanics is to relate the physical behavior (mechanical, conductive, etc.) to the ‘‘microstructure” – properties and geometrical arrangement of the constituents.
MICROMECH2014 is the premiere forum for the presentation of new advances and research results in the fields of analytical, computational and experimental micromechanics as well as on various applications of micromechanical modeling to problems of materials science, biomechanics, geomechanics etc. The conference will bring together leading researchers, engineers and scientists in this domain of interest from around the world.

Conference topics:
Fundamental aspects of micromechanics:
Microstructure-property relations
Effect of inhomogeneities’ shapes on overall properties
Cross-property relations
Theory of homogenization
Inverse problems of micromechanics
Computational micromechanics:
Multi-scale simulations of microstructure materials
Damage and fracture analysis
Deformation at microscale
Applied micromechanics:
Mechanics of composite materials
Micromechanical aspects of biomechanics
Micromechanical modeling in geomechanics
Applications of micromechanics to materials science

FURTHER INFORMATION
Deadline for abstract submission: 1 February 2014
Notification of acceptance: 1 March 2014
Grants supporting young researchers are available on application
MICROMECH2014 registration and other details:
http://fp7.imaps.aber.ac.uk/micromech2014/

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招生招聘
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天津大学力学系招聘启事

（天津大学丁千教授供稿）

天津大学力学系教学和科研岗位诚聘海内外杰出人才。天津大学力学专业现有专任教师50余人。主要研究领域包括：非线性动力学、振动与振动控制理论及应用，高速流动稳定性与层流-湍流转捩、环境与工业流体力学、计算流体力学，断裂与疲劳和界面力学、微纳米和生物力学，高性能计算与数值方法、实验力学等。近年来承担多项重要科研项目，希望加强和扩展以上研究领域。应聘者应具有力学及相关专业博士学位，以与以上领域相关的研究方向和兴趣，能够承担本科生和研究生课程的教学工作。
近期招聘讲师1名，有意应聘者请联系: muxx@tju.edu.cn或登录天津大学人事处招聘系统报名。有其他意向的应聘者也可与我们联系，优秀应聘者还可申报天津大学“北洋学者-海外杰出青年人才引进计划”项目(oplan@tju.edu.cn)。

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Postdoctoral Opening: Granular Physics (Experiment)
　

Applications are invited for one postdoctoral position in Experimental Granular Physics with the Collective Interactions Unit at the Okinawa Institute of Science and Technology (OIST). Our group is broadly interested in experimental softmatter physics, continuum mechanics, and applied mathematics, and their application to biologically inspired questions. Our current emphasis is on interfacial fluid dynamics, disordered granular solids, and biomechanics of the human foot. For further details about our group, please visit https://groups.oist.jp/ciu/

The current opening is for an experimental program in disordered granular solids with specific focus towards friction-induced hysteresis with analytical approaches borrowed from condensed matter physics and rock geophysics. Candidates should have a Ph. D. in experimental physics, mechanical/chemical engineering, geophysics or a related discipline, be comfortable working in English, and have demonstrated a creative and independent minded approach to research. The following technical skills are deemed essential for this position:

- Experimental Continuum Mechanics or Condensed Matter Physics

- Optics, Imaging and Image Analysis techniques

- Programming in C, C++, Matlab or equivalent

    - Hardware interfacing and analog electronics

    OIST offers an attractive package of remuneration and benefits, including support for relocation in Japan. The position can be taken up any time after February 1, 2014 (actual start date is negotiable), with an initial appointment for one year, and renewable for up to 3 years.
    Letters of application, with a CV, a short statement of research interests and contact details for a minimum of two (preferably three) referees should be sent to Mahesh Bandi [Email: bandi@oist.jp]. You are requested to seek your referees' consent prior to sharing their contact details. Applications will be reviewed as received, with the position remaining open until filled.
    OIST is an ambitious English language graduate university in Japan, with a strong international and interdisciplinary ethos. We are located in a coastal natural reserve, on the sub-tropical island of Okinawa, with a unique culture, breathtaking natural beauty, and easy and direct access to major destinations in Japan, China and Korea.

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学术期刊

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《SCIENCE CHINA Physics, Mechanics & Astronomy》

Special Topic: Airworthiness and Fatigue
(2014, Volume 57, Issue 1)

http://phys.scichina.com:8083/sciGe/EN/volumn/volumn_6444.shtml

http://link.springer.com/journal/11433/57/1/page/1

Foreword PDF (249KB)

Cite | SIH George C., HONG YouShi. Foreword. SCIENCE CHINA Physics, Mechanics & Astronomy, 2014, 57 (1): 1-1.

Adhesive bonding of composite aircraft structures：Challenges and recent developments PDF (1080KB)

Cite | PANTELAKIS Sp., TSERPES K. I.. Adhesive bonding of composite aircraft structures：Challenges and recent developments. SCIENCE CHINA Physics, Mechanics & Astronomy, 2014, 57 (1): 2-11.

Abstract: In this review paper, the challenges and some recent developments of adhesive bonding technology in composite aircraft structures are discussed. The durability of bonded joints is defined and presented for parameters that may influence bonding quality. Presented is also, a numerical design approach for composite joining profiles used to realize adhesive bonding. It is shown that environmental ageing and pre-bond contamination of bonding surfaces may degrade significantly fracture toughness of bonded joints. Moreover, it is obvious that additional research is needed in order to design joining profiles that will enable load transfer through shearing of the bondline. These findings, together with the limited capabilities of existing non-destructive testing techniques, can partially explain the confined use of adhesive bonding in primary composite aircraft structural parts.

Application of supersonic particle deposition to enhance the structural integrity of aircraft structures PDF (946KB)

Cite | Matthews N., Jones R., Sih G.C. Application of supersonic particle deposition to enhance the structural integrity of aircraft structures. SCIENCE CHINA Physics, Mechanics & Astronomy, 2014, 57 (1): 12-18.

Abstract: Aircraft metal components and structures are susceptible to environmental degradation throughout their original design life and in many cases their extended lives. This paper summarizes the results of an experimental program to evaluate the ability of Supersonic Particle Deposition (SPD), also known as cold spray, to extend the limit of validity (LOV) of aircraft structural components and to restore the structural integrity of corroded panels. In this study the potential for the SPD to seal the mechanically fastened joints and for this seal to remain intact even in the presence of multi-site damage (MSD) has been evaluated. By sealing the joint the onset of corrosion damage in the joint can be significantly retarded, possibly even eliminated, thereby dramatically extending the LOV of mechanically fastened joints. The study also shows that SPD can dramatically increase the damage tolerance of badly corroded wing skins.

Very-High-Cycle-Fatigue of in-service air-engine blades, compressor and turbine PDF (1100KB)

Cite | SHANYAVSKIY A A. Very-High-Cycle-Fatigue of in-service air-engine blades, compressor and turbine. SCIENCE CHINA Physics, Mechanics & Astronomy, 2014, 57 (1): 19-29.

Abstract: In-service Very-High-Cycle-Fatigue (VHCF) regime of compressor vane and turbine rotor blades of the Al-based alloy VD-17 and superalloy GS6K, respectively, was considered. Surface crack origination occurred at the lifetime more than 1500 hours for vanes and after 550 hours for turbine blades. Performed fractographic investigations have shown that subsurface crack origination in vanes took place inspite of corrosion pittings on the blade surface. This material behavior reflected lifetime limit that was reached by the criterion VHCF. In superalloy GS6K subsurface fatigue cracking took place with the appearance of flat facet. This phenomenon was discussed and compared with specimens cracking of the same superalloy but prepared by the powder technology. In turbine blades VHCF regime appeared because of resonance of blades under the influenced gas stream. Both cases of compressor-vanes and turbine blades in-service cracking were discussed with crack growth period and stress equivalent estimations. Recommendations to continue aircrafts airworthiness were made for in-service blades.

Fatigue strength of Al7075 notched plates based on the local SED averaged over a control volume PDF (902KB)

Cite | BERTO Filippo, LAZZARIN Paolo. Fatigue strength of Al7075 notched plates based on the local SED averaged over a control volume. SCIENCE CHINA Physics, Mechanics & Astronomy, 2014, 57 (1): 30-38.

Abstract: When pointed V-notches weaken structural components, local stresses are singular and their intensities are expressed in terms of the notch stress intensity factors (NSIFs). These parameters have been widely used for fatigue assessments of welded structures under high cycle fatigue and sharp notches in plates made of brittle materials subjected to static loading. Fine meshes are required to capture the asymptotic stress distributions ahead of the notch tip and evaluate the relevant NSIFs. On the other hand, when the aim is to determine the local Strain Energy Density (SED) averaged in a control volume embracing the point of stress singularity, refined meshes are, not at all, necessary. The SED can be evaluated from nodal displacements and regular coarse meshes provide accurate values for the averaged local SED. In the present contribution, the link between the SED and the NSIFs is discussed by considering some typical welded joints and sharp V-notches. The procedure based on the SED has been also proofed to be useful for determining theoretical stress concentration factors of blunt notches and holes. In the second part of this work an application of the strain energy density to the fatigue assessment of Al7075 notched plates is presented. The experimental data are taken from the recent literature and refer to notched specimens subjected to different shot peening treatments aimed to increase the notch fatigue strength with respect to the parent material.

From monoscale to multiscale modeling of fatigue crack growth：Stress and energy density factor PDF (1340KB)

Cite | SIH G.C. From monoscale to multiscale modeling of fatigue crack growth：Stress and energy density factor. SCIENCE CHINA Physics, Mechanics & Astronomy, 2014, 57 (1): 39-50.

Abstract: The formalism of the earlier fatigue crack growth models is retained to account for multiscaling of the fatigue process that involves the creation of macrocracks from the accumulation of micro damage. The effects of at least two scales, say micro to macro, must be accounted for. The same data can thus be reinterpreted by the invariancy of the transitional stress intensity factors such that the microcracking and macrocracking data would lie on a straight line. The threshold associated with the sigmoid curve disappears. Scale segmentation is shown to be a necessity for addressing multiscale energy dissipative processes such as fatigue and creep. Path independency and energy release rate are monoscale criteria that can lead to unphysical results, violating the first principles. Application of monoscale failure or fracture criteria to nanomaterials is taking toll at the expense of manufacturing super strength and light materials and structural components. This brief view is offered in the spirit of much needed additional research for the reinforcement of materials by creating nanoscale interfaces with sustainable time in service. The step by step consideraton at the different scales may offer a better understanding of the test data and their limitations with reference to space and time.

Multiscale approach to micro/macro fatigue crack growth in 2024-T3 aluminum panel PDF (732KB)

Cite | SIH G.C. Multiscale approach to micro/macro fatigue crack growth in 2024-T3 aluminum panel. SCIENCE CHINA Physics, Mechanics & Astronomy, 2014, 57 (1): 51-58.

Abstract: When two contacting solid surfaces are tightly closed and invisible to the naked eye, the discontinuity is said to be microscopic regardless of whether its length is short or long. By this definition, it is not sufficient to distinguish the difference between a micro-and macro-crack by using the length parameter. Microcracks in high strength metal alloys have been known to be several centimeters or longer. Considered in this work is a dual scale fatigue crack growth model where the main crack can be micro or macro but there prevails an inherent microscopic tip region that is damaged depending on the irregularities of the microstructure. This region is referred to as the "micro-tip" and can be simulated by a sharp wedge with different angles in addition to mixed boundary conditions. The combination is sufficient to model microscopic entities in the form of voids, inclusions, precipitations, interfaces, in addition to subgrain imperfections, or cluster of dislocations. This is accomplished by using the method of "singularity representation" such that closed form asymptotic solutions can be obtained for the development of fatigue crack growth rate relations with three parameters. They include: (1) the crack surface tightness δ^* represented by δ_o/δ_∞ = 0.3-0.5 for short cracks in region Ⅰ, and 0.1-0.2 for long cracks in region Ⅱ, (2) the micro/macro material properties reflected by the shear modulus ratio μ^* (=μ_micro/μ_macro varying between 2 and 5) and (3) the most sensitive parameter d^* being the micro-tip characteristic length d^* (=d/d_o) whose magnitude decreases in the direction of region Ⅰ→Ⅱ. The existing fatigue crack growth data for 2024-T3 and 7075-T6 aluminum sheets are used to reinterpret the two-parameter da/dN=C(ΔK)ⁿrelation where ΔK has now been re-derived for a microcrack with surfaces tightly in contact. The contact force will depend on the mean stress sm or mean stress ratio R as the primary parameter and on the stress amplitude σ_a as the secondary parameter.

Application of aluminum foil for “strain sensing” at fatigue damage evaluation of carbon fiber composite PDF (722KB)

Cite | PANIN Sergey, BURKOV Mikhail, LYUBUTIN Pavel, ALTUKHOV Yurii. Application of aluminum foil for “strain sensing” at fatigue damage evaluation of carbon fiber composite. SCIENCE CHINA Physics, Mechanics & Astronomy, 2014, 57 (1): 59-64.

Abstract: Surface layer of a loaded solid is an individual structural level of deformation that was shown numerously within concept of physical mesomechanics. This gives rise to advance in its deformation development under loading as well as allows using this phenomenon to sense the strain induced structure changes. It is of specific importance for composite materials since they are highly heterogeneous while estimating their mechanical state is a topical applied problem. Fatigue tests of carbon fiber composite specimens were carried out for cyclic deformation estimation with the use of strain sensors made of thin (80 μm) aluminum foil glued to the specimen's surface. The surface images were captured by DSLR camera mounted onto an optical microscope. Strain relief to form during cyclic loading was numerically estimated using different parameters: dispersion, mean square error, universal image quality index, fractal dimension and energy of Fourier spectrum. The results are discussed in view of deformation mismatch in thin foil and bulk specimen and are offered to be applied for the development of Structural Health Monitoring (SHM) approach.

Study of methods for evaluating the probability of multiple site damage occurrences PDF (836KB)

Cite | ZHANG JianPing, ZHANG JianYu, BAO Rui, ZHENG XiaoLing. Study of methods for evaluating the probability of multiple site damage occurrences. SCIENCE CHINA Physics, Mechanics & Astronomy, 2014, 57 (1): 65-73.

Abstract: Two methods currently available for evaluating the probability of Multiple Site Damage (MSD) occurrence were studied in this paper. One of the methods is a probabilistic analysis approach based on the statistical theory and fatigue characteristics of each structural detail, and the other is an approach which defines the initial damage scenario by means of Monte-Carlo simulation, and multiple initial crack scenarios are randomly generated. A modified method based on the Monte-Carlo simulation was proposed in this paper, in which the random fluctuation of the stress was considered to give more accurate evaluation results. In the presented method, the probability of MSD occurrence in a structural element containing multiple details was calculated based on the Monte-Carlo simulation and the p-S-N curve of a single structural detail. Fatigue tests were accomplished using specimens containing 21-similar-details to obtain the fatigue life corresponding to MSD occurrence. Tests on single-detail specimens and static calibration tests were also conducted to get the basic fatigue properties of the material and the degree of stress fluctuation. The aforementioned three methods were compared and validated via the test results. The influence of the stress random fluctuation degree on the probability of MSD occurrence and influence of the distribution types on evaluating the MSD occurrence probability were discussed.

Effects of loading condition on very-high-cycle fatigue behaviour and dominant variable analysis PDF (923KB)

Cite | LEI ZhengQiang, XIE JiJia, SUN ChengQi, HONG YouShi. Effects of loading condition on very-high-cycle fatigue behaviour and dominant variable analysis. SCIENCE CHINA Physics, Mechanics & Astronomy, 2014, 57 (1): 74-82.

Abstract: The specimens of a high carbon chromium steel were quenched and tempered at 150℃, 180℃ and 300℃. Such specimens were tested via rotating bending and a push-pull type of axial loading to investigate the influences of loading condition on the behaviour of very-high-cycle fatigue (VHCF). Experimental results show the different influences of inclusion size on the fatigue life for the two loading conditions. Predominant factors and mechanism for the fine-granular-area (FGA) of crack origin were discussed. In addition, a reliability analysis based on a modified Tanaka-Mura model was carried out to evaluate the sensitivity of inclusion size, stress, and ΔK_FGA to the life of VHCF crack initiation.

Fatigue crack growth in fiber-metal laminates PDF (827KB)

Cite | MA YuE, XIA ZhongChun, XIONG XiaoFeng. Fatigue crack growth in fiber-metal laminates. SCIENCE CHINA Physics, Mechanics & Astronomy, 2014, 57 (1): 83-89.

Abstract: Fiber-metal laminates (FMLs) consist of three layers of aluminum alloy 2024-T3 and two layers of glass/epoxy prepreg, and it (it means FMLs) is laminated by Al alloy and fiber alternatively. Fatigue crack growth rates in notched fiber-metal laminates under constant amplitude fatigue loading were studied experimentally and numerically and were compared with them in monolithic 2024-T3 Al alloy plates. It is shown that the fatigue life of FMLs is about 17 times longer than monolithic 2024-T3 Al alloy plate; and crack growth rates in FMLs panels remain constant mostly even when the crack is long, unlike in the monolithic 2024-T3 Al alloy plates. The formula to calculate bridge stress profiles of FMLs was derived based on the fracture theory. A program by Matlab was developed to calculate the distribution of bridge stress in FMLs, and then fatigue growth lives were obtained. Finite element models of FMLs were built and meshed finely to analyze the stress distributions. Both results were compared with the experimental results. They agree well with each other.

Scatter of fatigue data owing to material microscopic effects PDF (814KB)

Cite | TANG XueSong. Scatter of fatigue data owing to material microscopic effects. SCIENCE CHINA Physics, Mechanics & Astronomy, 2014, 57 (1): 90-97.

Abstract: A common phenomenon of fatigue test data reported in the open literature such as S-N curves exhibits the scatter of points for a group of same specimens under the same loading condition. The reason is well known that the microstructure is different from specimen to specimen even in the same group. Specifically, a fatigue failure process is a multi-scale problem so that a fatigue failure model should have the ability to take the microscopic effect into account. A physically-based trans-scale crack model is established and the analytical solution is obtained by coupling the micro-and macro-scale. Obtained is the trans-scale stress intensity factor as well as the trans-scale strain energy density (SED) factor. By taking this trans-scale SEDF as a key controlling parameter for the fatigue crack propagation from micro-to macro-scale, a trans-scale fatigue crack growth model is proposed in this work which can reflect the microscopic effect and scale transition in a fatigue process. The fatigue test data of aluminum alloy LY12 plate specimens is chosen to check the model. Two S-N experimental curves for cyclic stress ratio R=0.02 and R=0.6 are selected. The scattering test data points and two S-N curves for both R=0.02 and R=0.6 are exactly re-produced by application of the proposed model. It is demonstrated that the proposed model is able to reflect the multiscaling effect in a fatigue process. The result also shows that the microscopic effect has a pronounced influence on the fatigue life of specimens.

Fatigue damage rule of LY12CZ aluminium alloy under sequential biaxial loading PDF (585KB)

Cite | WANG YingYu, ZHANG DaChuan, YAO WeiXing. Fatigue damage rule of LY12CZ aluminium alloy under sequential biaxial loading. SCIENCE CHINA Physics, Mechanics & Astronomy, 2014, 57 (1): 98-103.

Abstract: A series of biaxial two-level variable amplitude loading tests are conducted on smooth tubular specimens of LY12CZ aluminium alloy. The loading paths of 90° out-of-phase, 45° out-of-phase and 45° in-phase are utilized. The fatigue damage cumulative rules under two-level step loading of three loading paths are analyzed. By introducing a parameter a which is a function of the phase lag angle between the axial and the torsional loading, a new multiaxial nonlinear fatigue damage cumulative model is proposed. The proposed model is evaluated by the experimental data for two-level loading, multi-level loading of LY12CZ aluminium alloy, and multi-level loading of 45 steel. Fatigue lives predicted are within a factor of 2 scatter band.

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部分期刊近期目录

Acta Mechanica Sinica Vol.29 No.6 2013

Mechanics of Materials Volume 69 February 2014

Theoretical and Applied Mechanics Letters (Vol. 3 No. 6)

Journal of the Mechanics and Physics of Solids Volume 62, January 2014

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《科学》公布2013年度十大科学突破
展望2014年值得关注科研领域

（摘自科学网）

        12月20日出版的《科学》杂志公布了2013年度十大科学突破：
1、癌症免疫疗法：
        癌症研究界在2013年经历了一个巨变，因为一个酝酿了数十年的策略终于确立了它的潜力。从癌症免疫疗法的临床试验出现了令人鼓舞的结果，在癌症的免疫疗法中治疗的标靶是身体的免疫系统而不是直接针对肿瘤。这种新的治疗会促使T细胞和其它免疫细胞来对抗肿瘤——而《科学》杂志的编辑们认为这些做法正在展现足够的前景而让其能登上本年度最重要的科学突破的榜首。
2、 CRISPR:
        这种基因编辑技术是在细菌中被发现的，但研究人员现在将其作为一种外科手术刀而指向了个体基因。其普及性在今年出现飙升，因为有超过12个研究团队用它来操控多个植物、动物及人类细胞的基因组。
3、钙钛矿型太阳能电池:
        一种新世代的太阳能电池材料在过去的这一年中获得了大量的关注，它们比那些传统的硅电池要更便宜且更容易生产。钙钛矿电池还没有像商用太阳能电池那样有效，但它们正在快速不断地得到改善。
4、结构生物学指导疫苗设计:
        今年，研究人员利用某种抗体的结构来设计一种儿童期病毒的免疫原——这是疫苗中的主要成分；该病毒每年会导致数百万人住院。这是第一次由结构生物学得来的如此强有力的对抗疾病的工具。
5、 CLARITY:
        这种成像技术在2013年改变了研究人员观察大脑这种复杂器官的方式，该技术使得脑组织变得透明并让神经元（以及其它的脑细胞）得到了充分地展示。
6、迷你器官:
        研究人员今年在体外生长迷你人样“类器官”上取得了显著的进步。这些类器官包括肝芽、迷你肾及微型大脑。这些迷你化的人类器官或被证明是比动物要好得多的人类疾病模型。
7、宇宙射线可追溯到超新星的残余物:
        尽管最初是在100年前被检测到的，但科学家们一直不确定来自外太空的被称作宇宙射线的高能粒子来自何方。今年，他们终于将这些射线与超新星或爆炸中的恒星所遗留的碎片云联系在了一起。
8、人类的克隆胚胎:
        意识到咖啡因在易损的人类卵细胞中起到了稳定关键性分子的重要作用后，今年，研究人员成功地从克隆的人类胚胎中得到了干细胞。
9、我们为什么要睡觉:
        在小鼠中的研究显示，脑子会在睡眠时通过扩展神经元之间的通道让更多的脑脊液流过从而更加有效地进行自我清理。该发现提示，恢复和修复都属于睡眠的主要目的。
10、我们的微生物，我们的健康:
        对数万亿的以人类身体为家的细菌细胞所做的研究已经弄清了这些微生物对我们有多大的影响。“个性化”药物需要将这些微生物租客考虑在内才能有效。

        12月20日出版的《科学》杂志展望2014年值得关注的科研领域，共4项，分别如下：
1，中微子研究
    2013年，科学家首次探测到来自太阳系外中微子，接下来，科学家将验证它们是否能够作为探测宇宙的有用工具。
2，临床基因组
    2014年，越来越多的研究人员，甚至医生，会要求病人进行基因组测序，这将有助于诊断罕见疾病和确定癌症疗法。
3，探寻宇宙历史
    “普朗克”探测器在2009年8月至2013年10月期间采集了相关天文数据，通过分析这些数据，欧洲宇航局研究人员有望在未来数月内绘出宇宙全景偏振图。
4，黑猩猩退休
    黑猩猩正在陆续“离开”美国科研实验室。多家美国政府或科研机构以多种方式取消实验中使用黑猩猩。一些科学家将不得不转向其它实验动物，或者彻底放弃相关研究。

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