材料力学科技实践题目

序材料力学科技实践活动的目的在于对材料力学的教学模式进行改革，目标是把学生被动的学习变为主动学习，给学生留出充分的创造性思维空间，锻炼学生动手能力，训练学生科学的观察、思考及总结的方法，并从中学到课本以外的知识，提高学生的综合素质。

具体方式：首先，在传统的授课计划内抽出一定学时，在大学二年级学生可以按时完成工作的前提下，以科研工作的形式要求同学分组选定研究题目。

课题的内容覆盖材料力学基本知识点，使用钢铁、有机玻璃、黄铜、铝合金、PVC、塑料、复合材料、混凝土等材料来完成剪切、挤压、拉伸、压缩、弯曲、扭转、结构失稳、冲击和应力腐蚀等项实验。

由于这些材料的机械性质各有差异（有些是目前工程上越来越多使用的新材料），力学响应的规律也不同。

目前使用的大部分材力教材没有详细介绍，课堂上也不讲实验中的现象，学生不知道实验的结果。

学生在教师的指导下自主选择实验方案，设计实验步骤和数值计算模型。

在研究过程中观察各种现象、采集处理实验数据。

根据在课堂教学中所学的知识点，学生通过文献检索对研究内容有基本认识。

在实验室里，由老师监督安全，可以较好完成实践动手的环节。

其次，为进行数值计算，预先给同学补充有限元的基本概念与使用方法。

要求结合有限元软件的教学穿插介绍相关的力学知识和基本理论, 但讲解以形象化、结论化为主, 舍弃大的理论推导过程。

结合实际工程间题, 提出计算分析的一般步骤，建立合理的计算模型, 实现有效的有限元模拟。

在使用有限元程序时，要求学生熟练掌握软件系统的有关操作内容，如图形界面、操作过程、功能块等。

学生自主完成数值模拟工作，最后写出研究报告。

研究报告内容渋及文献综述、方案描述、制备试样、试验方法和数据采集分析和数值模拟结果讨论等内容。

最后，以科技报告答辩会的形式完成。

在研究报告撰写中，即有写作格式要求，也给学生留下思考的空间。

学生通过分工查找资料，对实验现象和计算结果做出比较合理的解释。

Odeh Engineers, a local company led by David Odeh'93 has a number of projects.1、One involves the Tabernacle, a historic structure on Marth's Vineyard. They are involved inrehabilitating the structure, and need a nonlinear stress analysis for wind loading. The structure consists of various wrought-iron (or possibly a mix of wrought iron and cast iron) steel arches (similar to the Eiffel tower on a much smaller scale). They are getting some material samples tested over the next couple of weeks. Building plans would be used to model some of the structural elements to try to establish an ultimate strength interaction surface (P-M diagram) using the tensile test results.2、The company is also doing a couple of existing historic structures that require seismic retrofit. Often, we try to justify capacity for lateral load resistance in the structure using existing unreinforced brick masonry walls. There are various models for the behavior of these walls (e.g. equivalent strut), usually obtained through curve fitting of empirical test data. It would be useful to study the shear and bending characteristics of typical walls in historic buildings in RI, such as mill buildings, when subjected to lateral seismic forces. The project could aim to model the force/deflection and moment/rotation curves for typical cantilever shear walls (such as a simple brick masonry bearing wall and an "infill" masonry wall within a concrete beam/column frame). It would require research into test data for these wall types to determine models for material behavior.3、Another project is an investigation of the pullout strength of steel anchor bolts in concrete foundations. There are often uplift loads on building columns, which induces tension in anchor bolts at foundations. It would be interesting to study the stress distribution of a headed anchor bolt embedded in a concrete substrate to try to determine the ultimate strength in pullout for different conditions (e.g. vary bolt embedment depth, vary concrete substrate area and thickness, vary bolt diameter and/or bolt head size).4、Finally, one could look into modeling of cyclic loads on welded moment-resisting connections between steel beams/columns. These types of connections are hotly debated right now among structural engineers because many of them failed in the Northridge earthquake due to weld embrittlement and stress concentration at notches in the flange connections. Although alot of research has already been done in this area, it would be an interesting project to model the welded connection and try to mimic the failure modes exhibited in the Northridge quake.5、Professor Freund and Dr. Pradeep Guru are investigating the mechanical aspects of a very small condenser microphone. The design uses a thin low-stress polycrystalline silicon diaphragm suspended above a p+ perforated back plate. The microphone is fabricated using a combination of surface and bulk micromachining techniques in a single wafer process without the need of wafer bonding. Finite element analysis of the microphone is needed to assess its manufacturability and performance..6、Mike Joseph and James Peverill presented a number of potential topics that would contribute to the work of the Brown Formula SAE Car Project. The car components will ultimately be designed and built based on the results of the FEM studies. The project report can become part of the FSAE team's presentation at the 2002 competition and would considerably strengthen Brown's entry. Here are their suggestions.(1). Front axle(2). Rear axle (deDion)(3). Steering system(4). Braking system(5). Safety/Crashworthiness study involving chassis (frame)(6). Drivetrain study(7). Modeling tire behavior(8). Pedal system analysis(9). Thermal modeling of Cooling system(10). Model of entire vehicle during dynamic conditions7、 It appears as though the pedestrian overpass connecting the Fox Point Neighborhood of Providence with India Point Park has a fundamental natural frequency at or close to the typical cadence of people walking at a normal pace. Large-amplitude vibrations were noted when the bridge was crowded during the reason Heritage Festival at the park. An FEM analysis of the foot bridge could yield the natural frequencies and mode shapes for the bridge. A relation between computed stress field and vibration amplitude can predict levels of vibrations that the bridge may safely sustain. Added mass, dampers, or other retro-fit repairs could be investigated to alter the natural frequency or other dynamic response factors.8、Aeroastro, an aerospace company founded and led by Brown alumni. Has a contract to build a Carrier Spacecraft to be launched from an Ariane rocket. This carrier will in turn take a Sail craft out of the earth's orbit, deploy the sail and photograph the event. The sail itself will carry artifacts from humanity into deep space. Customers will pay in order to have their photographs, messages, and biological signatures launched into space. More about the project can be found at.FEM analysis of the carrier is needed as part of the design process.9、The August issue of the Brown Alumni Magazine calls attention to a recent study done by Brown Medical School Researchers on the danger of digging deep holes in dry sand at the beach. The authors looked into news reports of deaths due to hole collapse at beaches, and concluded that such deaths occur frequently enough to merit efforts to educate the public. The letter to the Journal of the American Medical Associsation. provides sccant information about the sizes of the collapsed holes and nature of the surrounding sand. A finite element study of sand holes of various sizes could lead to very specific information on the geometries most likely to lead to collapse in a particular sand type. The utility of such data to hole-diggers and lifeguards is obvious. The results of such a study could be submitted to the JAMA.10、Sierra Designs, a manufacturer of high-technology tents, is in the process of designing a new ultra light two-person tent. A pair of arching tent poles cross, and a rigid joint is being considered. In typical tent designs the poles cross but are not linked together by anything more constraining than a lose clip. The company is interested in FEM analyses of the proposed rigid connector.11、Analysis of dental restorations: implants, crowns, and bridges. For example, ceramic crowns have a 35% failure rate in the molar regions during the first three years after installation. The brittle nature of dental ceramics, the large magnitude of biting forces and improper crown designs can usually be blamed for failures. Is there a particular combination of the two dentist-controlled features, crown thickness and bonding material, that leads to better performance?12、Analysis of full-mouth dental implant systems. To replace all teeth, a dentist would insert titanium hollow-screw implants in the jaw, allow the bones to fuse with the screws. The implants are then uncovered and posts are attached to the head of the implants. This system is the foundation on which a one-piece set of molded teeth is set. The posts implants, and teeth are designed to handle compressive loads. depinding upon the fit of the tooth-piece and the location of the posts, chewing on the back, cantilevered molars may induce bending in the tooth piece and tension in some of the implants. Finite element studies can quantify these effects.13、Finite Element analysis of turtle (or other similar Animals) shells. A lab at Brown's Evolutionary Biology department is studying the phenomenon of hypoxia in turtle. Many species of turtles hibernate in iced-over water for long periods of time. Under these conditions, the mechanical properties of the shells are changed. How does this change affect the turtle's self-protective abilities? What is the effect of shell geometry on the mechanical response to various loads imparted by predators. Several students can be involved in this project, each modelling the geometry and properties for a different species of turtle. Live turtles and empty shells are available for measurement.14、Analysis of a 40-foot extension ladder. These ladders must be able to withstand a variety of loads in various combinations of extension and tilt angle. The dynamic properties are of particular importance. The ladder's natural frequencies must not coincide with the frequency of motion of a typically person climbing the ladder or working (hammering, scraping, etc) in various positions.15、Analysis of a bicycle brake. What are the stresses induced in brakes during braking in various road conditions? If several students are involved, a comparison of side-pull, center-pull, and V-type brakes could be made.16、Another important part of a bicycle's braking system is the brake shoe/pad assembly. These are subject to compressive and shear forces while in contact with the rim. The tread configuration, angle subtended by the brake and rim, and material properties all effect the stress distribution.17、Bike frames have changed greatly over the years. Compare the stress distributions in various frame geometries. Perhaps a comparison of men's and women's frames would interest you, or an analysis ofone of the new style suspension mountain bikes. You could study the frame of a tandem bicycle. The dynamic properties of tandem and suspension bikes are important; natural frequencies of the frames may be close to the cadence of the pedaling.18、The arch in the new addition to Barus Holley building is concave, and often significant winds blow up the walkway and attack the arch at various angles. How does the arch respond? The curved glass sliding doors may be vulnerable to breakage. What winds can be sustained? Are such winds likely to occur?19、Remember EN4, and that lab comparing the efficiency of various bows? You could do an FEM analysis of any of the three bows. A static analysis would show the stress distribution in the bow and could give the bow's natural frequencies. The ambitious can try dynamic analyses.20、This may sound silly to you, but the mechanics of food are very important. Consider, for example, Nabisco Animal Crackers. For these to be a successful and profitable product, the cookies must arrive in the consumer's hands largely unbroken. The combination of material properties and geometry must be just right in order for this to occur. Other types of food (crackers, chips, etc, etc) have the same problem.21、The mechanical properties of packaging: boxes, bottles, cans, are of extreme importance. The goal in package design is to minimize weight and production costs while maintaining adequate structural integrity and thermal response. Moreover, the package must be efficiently stored, and appealing to the consumer.22、Some species of spiders spin their webs with as many as 7 silks with differing elastic properties. The static response to wind, rain, and insects of various webs could be explored. The natural frequencies of vibration and vibrational modes of webs are also of interest; spiders are thought to sense the location of their prey by the vibration of their web.23、How have trees adapted to their environment? What are the mechanical constraints placed on a tree's trucnk, root, and branch systems? What role do wind and soil conditions play in these constraints?24、连接销钉在不同排列方式下的剪切失效分析25、挤压件在不同接触方式下的挤压应力分布，变形与失效分析26、具有不同形状孔洞的结构物在拉伸条件下的应力分布及失效分析27、不同形状的结构物在压缩条件下的失稳模式及失效分析28、不同截面形状的结构物在扭转条件下的应力分布及失效分析29不同形状的结构物在冲击条件下的失效与断裂机理分析30、不同形状的结构物在预应力条件下的应力腐蚀行为机理分析31、不同形式的复合增强（如：颗粒增强、纤维增强、编织物增强、缝制增强、包裹增强等）结构物在复杂载荷条件下的失效机理分析。