Structural Materials Commons^™

Physical Properties Of Copper Niobium Nanolamellar Composites Fabricated By Accumulative Roll Bonding, Jared Justice

Nuclear Engineering ETDs

Nanolamellar composites with high interface density have increased strength due to interfaces serving as barriers to dislocation movement and high radiation damage resistance. However, these interfaces also serve as barriers to electron motion, reducing the electrical resistivity and thermal conductivity. This work seeks to understand the inherent tradeoff between strength and physical properties of nanolamellar composites produced by accumulative roll bonding with layer thickness ranging from 25 nm to 193 nm. The electrical resistivity was investigated over temperatures ranging from 2 K to 300 K. The effect of longitudinal rolling and cross rolling was also investigated. Electrical resistivity results were …

Mechanical Characterization Of Functionally Graded M300 Maraging Steel Cellular Structures, Bradley Jay Sampson

Theses and Dissertations

Traditional methods for increasing the energy absorption of a structure involve using a stronger material or increasing the volume of the structure, resulting in a higher cost or additional weight. Additive manufacturing (AM) can be used to maximize the energy absorption of materials with the ability to create complex geometries such as cellular structures. Previous work has shown that the energy absorption of additively manufactured parts can be improved through functionally graded cellular structures; however, this strategy has not been applied to ultra-high strength steel materials. This work characterizes the effect of multiple functional-grading strategies (e.g. uniform, rod-graded, size-graded) on …

A Review On Ship Recycling Industry In Bangladesh From Global Perspective, Ahammad Abdullah, Zobair Ibn Awal, M Ziauddin Alamgir, Md. Jobayer Mia, Farihatul Mim, Utpal K. Dhar

Journal of Ocean and Coastal Economics

At present, the global center of the ship breaking and recycling industry is in South Asia, specifically Bangladesh, India, and Pakistan. These three countries account for 70–80 percent of the international recycling market for ocean-going vessels, with China and Turkey covering most of the remaining market. Only about 5 percent of global volume is scrapped outside these five countries. Bangladesh has environmentally beneficial coastal region and affordable labor that make the shipbreaking and recycling business as a potential sector for the country. In addition, ship recycling and its related businesses are helping to solve our nation’s unemployment issues at all …

Structural Performance And Resiliency Of Reinforced Concrete Bridge Pier Columns, Multi-Column Piers, And Bridge Systems Subjected To Multiple Hazards – Fire, Collision, And Air Blast, Qusai Abdulkarim Alomari

Dissertations and Doctoral Documents, University of Nebraska-Lincoln, 2023–

Given their close proximity to traffic and improper employment of protective systems, bridges and bridge piers are vulnerable to multi-hazard events triggered by vehicle collisions coupled with correlated and cascading events, such as explosions and fires. Despite recent catastrophic incidents that have highlighted the profound consequences of these extreme demands, including substantial damage, adverse economic impact, and loss of life, there has been a notable lack of research investigating the performance of bridges and bridge structural components under the aforementioned multi-hazards. Furthermore, current bridge design codes do not address these events assuming that, after these destructive events, replacement of the …

Cfrp Delamination Density Propagation Analysis By Magnetostriction Theory, Brandon Eugene Williams

All Dissertations

While Carbon Fiber Reinforced Polymers (CFRPs) have exceptional mechanical properties concerning their overall weight, their failure profile in demanding high-stress environments raises reliability concerns in structural applications. Two crucial limiting factors in CFRP reliability are low-strain material degradation and low fracture toughness. Due to CFRP’s low strain degradation characteristics, a wide variety of interlaminar damage can be sustained without any appreciable change to the physical structure itself. This damage suffered by the energy transfer from high- stress levels appears in the form of microporosity, crazes, microcracks, and delamination in the matrix material before any severe laminate damage is observed. This …

Thermo-Mechanical Instabilities In Next-Generation Friction Materials In High-Speed Sliding Systems, Kingsford Koranteng

Electronic Theses and Dissertations

For centuries, the manufacturing industry has incorporated metals like copper into friction materials to enhance thermal properties and minimize thermo-mechanical instabilities (TMI) in high-speed sliding systems. Unfortunately, these metals have adverse environmental effects due to the emission of hazardous particulate matter. As a result, there is a growing movement towards adopting next-generation friction materials as an alternative solution.

The study begins by conducting experimental and numerical investigations to examine the instabilities found in metal-based friction materials. The primary objective is to utilize the insights gained from the investigations to computationally explore effective strategies for mitigating various instabilities that may arise …

Implementation Of Experimental Static Recrystallization Of High Strength Steel Into Computational Simulation Of Multi-Pass Slab Hot Rolling, S. K. Dasari, S. Ganguly, A. Abutunis, K. Chandrashekhara, M. F. Buchely, S. N. Lekakh, R. J. O'Malley, T. Natarajan

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Microstructural changes and softening due to static recrystallization have a critical influence on thermo-mechanical behavior of high strength steels during industrial multi-pass hot rolling. Numerical simulation using finite element analysis (FEA) can be used to accurately predict the softening behavior during the hot rolling process. Therefore, the implementation of an experimentally defined static recrystallization model into FEA is necessary to get realistic simulation prediction. in this study, the extent of softening during static recrystallization in Si and Mn alloyed high strength steel was measured using double hit tests. a Gleeble™ thermo-mechanical simulator was used to perform the double hit tests …

Evaluation Of Novel Jointless Engineered Cementitious Composites Ultrathin Whitetopping (Ecc-Utw), Ricardo Hungria

LSU Doctoral Dissertations

Ultrathin Whitetopping (UTW) is a rehabilitation technique that consists of placing a thin layer of concrete over a damaged asphalt pavement. While UTWs have demonstrated satisfactory performance in field tests, the inherent brittleness of concrete has led to the appearance of distresses. To address these distresses, Engineered Cementitious Composites (ECC) have been proposed for UTW applications, thanks to their exceptional attributes, including tensile ductility, flexural performance, and fatigue resistance. In this study, an ECC-UTW was constructed to investigate its potential as a viable solution. The project comprised two 18.3 m ECC sections with different thicknesses, namely 63.5 mm and 101.6 …

Feasibility Study Of Pavement Rutting Evaluation Method Based On Driving Vibration, Zhang Jinxi, Wang Peirong, Cao Dandan, Ceng Jingxiang

Journal of China & Foreign Highway

To explore the intelligent detection and monitoring methods of pavement performance, this paper utilized the self-developed driving data collection app to collect vibration acceleration and other data of the pavement during driving, and carried out the feasibility study of evaluating the pavement rutting by driving vibration. Firstly, the collected vibration acceleration data was processed for noise reduction, and the driving vibration characteristics in different working conditions were analyzed. Secondly, seven time domain indicators with high correlation between vibration acceleration and the rutting were extracted as the initial set of indicators, and the seven indicators were downscaled into two independent principal …

Influence Of Shear Deformation On Manufacturing And Erection Alignment, Wang Jin, Chen Changsong

Journal of China & Foreign Highway

This paper aims to study the effect of shear deformation on the manufacturing and erection alignment of main girders of free cantilever erection steel box girder bridges and better design the state of bridge formation state. To this end, it calculated the shear stress coefficient of uniformity of the steel box girder’s cross-section by adopting the finite element method and conducted comparison with the solid model of the plate and shell units of the steel box girder. The results show that the shear stress coefficient of uniformity calculated by finite element software is accurate and reliable. Additionally, simple modeling indicates …

Study On Temperature Gradient Of Long-Span Single-Box Double-Chamber Box Girder Bridge, Yang Wenbin

Journal of China & Foreign Highway

In view of the complex temperature effect of the single-box double-chamber box girders, this paper aimed to carry out the temperature gradient study of box girder cross-sections by employing a short-tower single-box double-chamber cable-stayed bridge with span arrangement of (120+120) m. 21 temperature sensors were installed at the cross-sections of large-mileage closure sections, with the set collection frequency of one time per hour and a wireless collection module for data collection. Meanwhile, temperature observation was carried out for a period of 171 d to obtain the distribution law of the temperature gradient in cross-sections of the closure sections. The study …

Experimental Study On The Influence Of Cantilevered Sidewalk On The Wind Resistance Of A Cable-Stayed Bridge With Pk Girder, Yu Zhenghua

Journal of China & Foreign Highway

Bilateral box steel main girders are widely employed in large-span double-plane cable-stayed bridges. These bridges are characterized by low frequency, small damping, and relatively light mass, and their wind resistance stability is a key problem to be solved in bridge construction. By taking the Pingnan super major cable-stayed bridge with a main span of 636 m on Pingrong Expressway under construction as the research project, this paper built a finite element spatial model of the bridge and analyzed the structural modal characteristics. Meanwhile, it carried out the main girder segmental model of elastically suspended vortex vibration and chatter vibration wind …

Orthogonal Analysis Of Influential Factors In Construction Of Portal Pier Foundations Adjacent To Existing Railway, Li Minghua, Feng Jiahui, Han Wenjing

Journal of China & Foreign Highway

To study the influencing factors of portal pier foundation construction adjacent to existing railway, this paper adopted the orthogonal test method based on numerical simulation to study the influence of five factors on the existing railway, including the length of bored piles, construction sequence of bored piles, excavation depth of foundation pits of the bearing platform, length of steel sheet piles, and number of steel sheet piles. The results show that during the bored pile construction stage, the most important factor is the construction sequence of bored piles. Meanwhile, during the stage of foundation pit excavation and substructure construction, the …

Optimization Design Of Highway Tunnel Inner Contour Based On Simu Lated Annealing Algorithm, Zhang Qingwei

Journal of China & Foreign Highway

To optimize the inner contour design of road tunnels, this paper regarded the inner contour design of a road tunnel as an optimization problem in certain conditions. By taking the area optimization as the objective, it introduced the simulated annealing algorithm to solve the problem based on the calculation model building of the inner contour of a single-centered circle with an inverted arch, with a program written for verification and analysis. The results show that the optimization design scheme is feasible and can provide an idea way for the inner contour design of road tunnels.

Comparison Of Specifications For Highway Safety Audi Ts Of China ， The United States ， And Australia, Li Jie, Han Huanhuan, Li Jia, Ren Yabo, Gong Ruiming

Journal of China & Foreign Highway

Traffic safety is one of the three major problems of transportation. To build a transportation power, China has proposed the call of “facilitating the transportation development from pursuing the speed and scale to paying more attention to quality and safety”, and improving the audit specifications of road safety is an important basis for increasing the transportation safety level. This paper firstly introduced the background where China, the United States and Australia issued the audit specifications of road safety, and then compared the differences between the three countries in the aspects of the audit process for road safety, audit indexes and …

Research On A Hub Interchange Scheme Under Special Terrain Conditions, Wang Jie, He Yajun

Journal of China & Foreign Highway

By combining the study process and conclusion of the interchange scheme of the Lugao hub as an important node of G4216 Jinyang-Ningnan Expressway Project, this paper discussed the ideas and methods of selecting the hub interchange shape under complex terrains and high functional requirements. It aimed to provide certain references for the design of hub interchange schemes in special Y-shaped terrain conditions. The Lugao hub interchange location is deeply cut by the Jinsha River and its branches, with narrow valley bottoms, extremely steep cross slopes, and harsh engineering construction conditions. Meanwhile, in the limited space, the specific requirements of the …

Structure Design Of Platform For Construction Of Inclined Pile Foundation On The Water Under Complex Hydrogeology Conditions, Cheng Tao, Fu Su, Deng Songtao

Journal of China & Foreign Highway

Based on the design of the pile foundation construction platform for the Yushan water intake in Daishan Port, this paper introduced the adoption of the support system combining the steel pile casing and steel pipe piles in complex hydrogeological conditions. Most of the pile foundations feature small embedded length and are inclined piles with weak lateral rigidity, and they cannot resist the horizontal loads such as wind-wave-current during the typhoon period. Therefore, this paper introduced several measures taken to improve the overall lateral stability of the platform. The first measure is to improve the boundary conditions of pile foundations by …

Study On Stability Analysis And Treatment Of A Expressway Landslide, Huang Hongchao

Journal of China & Foreign Highway

In highway construction of mountainous areas, landslides are easily triggered due to the complex geological conditions, thereby causing serious economic loss and even casualties. Therefore, the study of landslide treatment schemes has caught increasingly more attention from scholars. By taking the giant landslide treatment on a highway of southeastern Yunnan as an example, this paper analyzed the process and cause of giant landslide formation, and then conducted inverse calculations to determine the stability analysis parameters of landslides via combining the topography and geology and slope state before and after slope excavation. Finally, according to the calculation results of the residual …

Discussion On Treatment Scheme Of Soft Foundation Based On Cooperative Deformation Of Roadbed And Frame Structure, Liu Jizhong, Chen Kai, Yang Fengyu

Journal of China & Foreign Highway

In view of insufficient consideration of cooperative roadbed and structure deformation, by taking the soft foundation with frame structures in the fill roadbed as the research object, this paper adopted Midas GTS NX finite element analysis software to simulate the pavement settlement and plastic zone distribution of the soft foundation treated by cast-in-place piles. Considering that the stiffness difference between the roadbed and the frame structure can easily result in pavement cracking, a variable stiffness composite foundation treatment optimization scheme was proposed. This scheme coordinated the cooperative settlement and deformation of the roadbed and frame structure, and prevented the development …

Research On Effect Of Structural System On Static And Dyn Amic Stiffness Of Large-Span And Narrow Suspension Bridges, Song Songke, He Jiayong, Chen Qian, Du Taoming, Li Yongle, Yu Chuanjin

Journal of China & Foreign Highway

Large-span and narrow suspension bridges featuring flexible structures and low overall stiffness have prominent wind resistance problems. Structural static and dynamic stiffness is the basic parameter for wind resistance of long-span bridges. By taking a large-span and narrow suspension bridge as the research project, this paper comparatively analyzed the effects of parameters such as stiffened girder stiffness, main cable span ratio, main cable spacing, and lifting point width on the static and dynamic stiffness based on the theory of spatial cable segmental suspension lines and three-dimensional finite element models of bridges under multi-working condition systems. The results show that the …

Risk Assessment Calculation Of Layered Surrounding Rock Tunnel Based On Combination Weight-Eahp-Ncm Model Theory, Yang Yongbin, Wang Qing, Wang Yijun, Gao Weizheng, Li Yongliang

Journal of China & Foreign Highway

To accurately assess and calculate the structural stability of layered surrounding rock tunnels during construction, this paper firstly constructed a risk assessment index system for layered surrounding rock tunnels based on the consideration of factors of hydrogeology, structural surfaces, engineering, external forces, and topography and geomorphology. Based on the Delphi method (DELPHI) and entropy weight method (EWM), the combination of indicators was assigned. Based on the typical event samples and the mining of classical domains-joint domains of the assessment system, the extension analytic hierarchy process calculation model (EAHP) and normal cloud computing model (NCM) were built to assess the stability …

Study On Low Temperature Performance Of Asphalt Mixture Under Salt Freezing Condition, Song Yunlian, Gao Pan, Jiang Yu

Journal of China & Foreign Highway

To investigate the ice-melting ability of snow-melting agents and the effect of different salt freezing conditions on low temperature performance of asphalt mixtures, this paper carried out the ice-melting ability test, beam bending test and beam bending creep test. The results show that under the temperature of -20℃ and concentration 30% or more of the snow-melting agent, the ice can be melted. However, the melting ice quality is small. In terms of melting ice quality, the melting ability of the P-type snow-melting agent is better than that of the H-type snow-melting agent. Under the temperature of -10‒0℃, the recommended concentration …

Analysis Of Light Reflection And Automobile Exhaust Degradation Effect Of Asphalt Pavement Coating, Shang Wenyong, Zhou Zheng, Chen Jun

Journal of China & Foreign Highway

To compare the light reflection and exhaust degradation effect of common road coating fillers, this paper prepared three kinds of road surface coatings with Nano-TiO2, Nano-ZnO, and Micro-TiO2 as fillers respectively. Meanwhile, the reflectivity tests of the coatings with different mixing contents of fillers were conducted by adopting a self-developed light reflectivity tester to determine the optimal mixing content of fillers. Under the optimal mixing content of fillers, the reflectivity of three kinds of coating asphalt mixtures was tested to compare the light reflectivity effect of Nano-TiO2, Nano-ZnO and Micro-TiO2. Additionally, a self-developed exhaust concentration analyzer was utilized to test …

Study On Effect Of Nanomodified Additives On Properties Of Concrete Mixtures During Winter Season, Li Yulin, Liang Hongjie, Liang Junlin, Rong Hongliu, Yang Xiaolong

Journal of China & Foreign Highway

To solve the difficult placement of small structures on highways caused by the decreasing workability of cement concrete construction in winter seasons, this paper developed a nanomodified additive to investigate its effect on the performance of cement concrete. Sulfonate naphthaleneformaldehyde (SNF), nanoSiO2, rosin soap (WSR) and sodium nitrate (NaNO3) were formulated into a variety of additives in different ratios and mixing contents to prepare cement concrete, with the fluidity, segregation and compressive strength studied. The results show that the optimal ratio (mass) of nanomodified additives is SNF:0.4%, nanoSiO2:0.1%, WSR:0.05%, and NaNO3:4.0%. The fluidity, segregation and compressive strength of the concrete …

Study On Theoretical Relationship Between Acceleration Of Vehicle Suspension And International Roughness Index, Lv Wenjiang, Zhang Zhen

Journal of China & Foreign Highway

The international roughness index (IIRI) has become one of the most widely employed indexes to characterize the surface roughness. However, there are still some problems in the current research on the calculation of this index by adopting vertical acceleration data of vehicles. For example, the influence of vehicle suspension parameters on the test results is not sufficiently taken into account, and the applicability of regression analysis equations between vehicle acceleration and this index is low. This paper studied a method of determining this road surface roughness index with the suspension parameters of the test vehicle considered. The actual road tests …

Study On Influence Of Different Subgrade Types On Low Temperature Shrinkage Performance Of Asphalt Pavement, Xu Yongli, Guo Yang, Sun Zhiqi

Journal of China & Foreign Highway

To study the influence of different subgrade types on the low-temperature shrinkage performance of asphalt pavement, this paper designed two kinds of asphalt pavement combination structures for the semi-rigid subgrade and flexible subgrade: AC-16+cement-stabilized gravel and AC-16+asphalt-stabilized gravel. Strain gauges were attached at the center of the sides of the two materials and at the characteristic positions of the interfaces between the layers, and the resistance strain gauge measurement method was employed to carry out the temperature shrinkage test of the combined structure and thus obtain the strain changes at each position during the cooling process, with the influence of …

Research On Design Method Of Anti-Overturning Stability Of Large Cantilever Steel Truss Beam Traverse Construction Based On Reliability Inversion Theory, Yang Shusheng, Cui Fengkun, Wang Jiansheng, Su Baozhong, Xu Shaoxia

Journal of China & Foreign Highway

To evaluate the safety of large cantilever steel truss beams in traverse construction, this paper proposed a method of evaluating the safety factor of anti-overturning stability of large cantilever steel truss beams based on the reliability inversion theory. Under the premise of giving the target reliability index and considering the randomness of the structural parameters, this method adopted the reliability inversion theory to solve the anti-overturning safety factor of large cantilever steel truss beams in traverse construction. Finally, the method was utilized to study the anti-overturning stability of the 82 m large cantilever steel truss beam of Weilai High-speed Railway …

Analysis Method And Evaluation Of Fatigue Life Of Welded Cable Clamp, Li Hongsheng, Zhang Zhixin, Xue Songling, Wang Zhicheng

Journal of China & Foreign Highway

In view of the practical application of welded cable clamps in Xintian Yangtze River Bridge, this paper adopted numerical calculation to analyze the fatigue performance of welded cable clamps and evaluate the fatigue life of the clamps. Firstly, a finite element model for Xintian Yangtze River Bridge was built to analyze the static characteristics of the bridge under constant and fatigue loads. Then, the geometric configuration of the welded cable clamps was analyzed and a numerical model of welded cable clamps was built, with the submodel technique adopted to analyze the mechanical properties of the clamps under different loads. Finally, …

Review Of Material Composition And P Erformance Evaluation Of Cold Patch Asphalt Mixture, Yang Yanhai, Zhu Guangxu, Yang Ye

Journal of China & Foreign Highway

To summarize the latest research achievements of cold patch asphalt mixtures at home and abroad, and to promote their development and application, this paper firstly introduced the development history of cold patch asphalt mixtures domestically and internationally, and focused on summarizing the classification and material selection of materials, as well as common mix ratio design methods. Secondly, it reviewed and analyzed the influencing factors of performance evaluation of the mixtures. Finally, such problems as the strength effect mechanism and the link between the material and performance, and the future research directions were combined to establish a unified and effective evaluation …

Study On Influence Factors Of Temperature Field Of Crc+Ac Composite Road Surface, Cheng Xiaoliang, Zhang Hao, Li Sheng

Journal of China & Foreign Highway

In view of the factors influencing the temperature field of CRC+AC composite road surfaces, this paper analyzed the temperature field distribution and influencing factors of CRC+AC composite road surface structures based on the meteorology and heat transfer theories, and conducted 3D solid modeling and numerical simulation by adopting Abaqus finite element software. The results show that in certain conditions, the deeper distance from the road surface leads to smaller temperature change of the road surface structure. When the depth exceeds 0.6 m, the temperature is almost unchanged and has little difference with the outside ambient temperature. By increasing the thermal …