Local Strengthening Research Articles

Investigation of tensile deformation behavior of a TWIP/TRIP metastable β titanium alloy at typical temperature part Ⅱ: 20 K

The tensile behavior and deformation mechanism of Ti-10Mo alloy at liquid hydrogen temperature (20 K) were investigated. The results showed that Ti-10Mo alloy has a high UTS of 1553 MPa and a high YS of 1497 MPa at 20 K, as well as an excellent elongation after fracture of 11 %. This is due to the simultaneous activation of {332}<113> twin twins and SIM α“ transformation during deformation, that is, the combination of TWIP and TRIP effects. The activation sequence of different deformation mechanisms is as follows: the primary SIM α” and {332}<113> twins are first activated simultaneously. With the increase of strain, multiple variants of SIM α“ and {332}<113> twins can be activated in a grain. Then the primary SIM α” can be further transformed into {130}<310>α“ twins. With the further increase of strain, some {130}<310>α” twins can continue to be transformed into secondary {332}<113>β twin and some primary {332}<113> twins can also produce secondary α“ to continue the deformation. When necking, a large number of {111}α” twins are activated to further coordinate the plastic deformation. In addition, the multiple necking phenomenon is due to the further activation of {332}<113> twins and SIM α“ during the necking of a certain area due to stress concentration during the stretching process, which causes local strengthening and resulting in the stop of necking. Finally, the serrations on the stress–strain curve may be caused by multiple necking.

Gradient structured Al alloy with a synergistic improvement of strength-ductility obtained by friction stir processing

One Al 6061 with gradient microstructure is prepared by friction stir processing (FSP). Microscopic characterization indicates that the regulation of grain size gradient could be achieved by adjusting the process parameters of FSP. The mechanical property test indicates that one gradient Al 6061 combines an ultimate tensile strength of 266 MPa with a uniform elongation of 27 %, and the other comes 258 MPa with 29 %, which provides an excellent combination of strength and ductility. Moreover, the molecular dynamics (MD) method is employed to reconstruct and simulate the mechanical behavior of the gradient region and the dynamic evolution of the microstructure. When the stacking faults (SFs) with antisymbolic Burgers vector meet and detwinning occurs, grain refinement will induce localized strengthening. When the Shockley partials occur cross-slip, numerous sessile dislocations obstruct the dislocation motion more facilitate strain hardening. Meanwhile, a unique interaction mechanism between shear bands (SBs) and intergranular cracks in Al 6061 is discovered in plastic deformation. The coarse net-like SBs in the small-grain region are highly susceptible to catastrophic fracture of the material, and the large cracks formed within the severely band-like SBs in the large-grain region weaken the strength substantially. However, the formation of sessile dislocations in the gradient region effectively mitigates strain localization and inhibits the nucleation of large cracks. The results interpret the dynamic evolution process of gradient microstructure prepared by FSP and the mechanism of strengthening and toughening and provide process and theoretical references for the research and development of new engineering materials.

Local reinforcement of adhesively bonded square shape aluminum energy absorber with CFRP under quasi-static axial loading: An experimental and numerical study

This study presents experimental and numerical investigations on the effects of composite ply angle, thickness and number of layers on energy absorption behavior of adhesively bonded carbon fiber-reinforced plastic/aluminum hybrid structure under quasi-static axial loading. This paper aims to use the advantages of adhesive bonding for the local strengthening of a square shaped aluminum energy absorber by composite and as a result achieving desirable energy absorption behavior prior to failure in the connection and without heterogeneous deformation of the structure while reducing the weight of the structure and usage of material and at the same time obtaining favorable results compared to the traditional ways like reinforcing the aluminum structure with composite globally. For this purpose, two models were made and analyzed; one reinforced with four L-shaped composites adhesively bonded using Araldite 2015 to four outside corners of the aluminum square and the other reinforced locally to four corners from within the square. Finite element model was developed for analysis of these hybrid structures. Five different ply angles for composite and multiple number of composite layers varied from 2 to 8 layers under the same and different thicknesses were investigated. Moreover an alpha factor has been determined to measure the importance of local reinforement of the square shape aluminum energy absorber by L-shaped composites. The results showed that compared to aluminum and aluminum with global composite reinforcement energy absorbers, due to the adhesive connection between aluminum and composite in the locally reinforced CFRP/aluminum specimen, the composite had better energy absorption by following the collapse pattern of aluminum and creating a continuous collapse and failure modes. The results indicated good coordination and agreement between the simulated models and the experimental tests. The findings from this experiment demonstrates significant potential for local reinforcement of structures employing adhesives. Utilizing such connections and the ability to strengthen specific areas based on arbitrary geometry and strengthening location could offer substantial opportunities in constructing lightweight structures with high energy absorption across diverse applications.

Investigation of the H2 dissociation and strengthening mechanism in vacancy-induced graphene

Atomic vacancies play a crucial role in hydrogen storage and local strengthening of a substance with a mechanism that is elusive. First-principles examinations of monolayer graphene unveiled the following: (i) the neighboring carbon atoms move radially away from the vacancy center with a 3–10% C–C bond contraction, generating a circumferential density ribbon of energy and electrons; (ii) the dense electrons within the ribbon polarize the edge atoms into dipoles pointing to the center; (iii) the polarized electrons coupled together to for the vacancy dipole, resulting in the Dirac-Fermion resonant peak at Fermi energy and the energy density gai raise the local strength; and (iv) the vacancy dipole induces the adsorbed H2 molecule into H+-H- dipole to stabilize H2 adsorption. The findings of vacancy reinforcement, dipole formation, and stable H2 adsorption should provide a promising mechanism contributing to the advancement of hydrogen storage theory.

Role of Commodity Market in Economic Development: A Study of Major Markets of Bagamati Province

Market usually plays a vigorous role fulfilled peoples demand and also strengthen the capacity of trade management system, always support the national economy of the country. Supply system and demands maintain the requirement and functional operations in a market. This study aims to analysis the role of commodity markets in the positive economic development in context of Nepal. The major markets such as Narayanghat, Nuwakot, and Banepa from the Bagamati Province were chosen representative purposively samples. The study was further executed through the primary and secondary research mode as well as consultative meetings and Key Informant Interview were conducted. The study revealed that Paddy, wheat and maize cereals are the topmost commodities in the area. Paddy is high in demands due to consumption. The local producers sufficient for some 2-3 months during season, for the rest of the months,’ supply from neighbor’s district, Terai region and India playing a leading role to fill the demand, agent booking is another mode of supply, India and Terai region are the major sources of supply management. Some 60 % local production are available for 2-3 months in the local market making income and contributing the national economy. Study concluded, as local production played a vital role in the economy of the nations due to comprehensive farm gate price and ongoing supply. Local production strengthening is advised.

Localized phase transformation strengthening in CoNi-based superalloys

Segregation processes during high-temperature deformation can be either detrimental or beneficial in γ′-strengthened superalloys depending on which elements segregate. In intermediate CoNi-based superalloys only softening due to extensive microtwinning was observed so far. By analyzing the creep behavior of a Ta-free and a Ta-containing CoNi-based superalloy at 750 °C and 620 MPa, we show that strengthening segregation behaviors along various planar defects, including microtwinning, can be achieved in this alloy class. While both alloys deformed under planar fault formation, the Ta-containing alloy outperformed the Ta-free alloy. Atomic-scale energy dispersive spectroscopy investigations revealed strengthening effects by local phase transformations along superlattice intrinsic and extrinsic stacking faults in both alloys. However, microtwinning is enhanced in the Ta-free alloy, while it is impeded in the Ta-containing alloy. Given the faster diffusivity of Ta compared to W, kinetic effects on localized phase transformation strengthening and their subsequent influence on the creep behavior are discussed.

The multi-stage plasticity in the aggression circuit underlying the winner effect.

Winning increases the readiness to attack and the probability of winning, a widespread phenomenon known as the "winner effect". Here, we reveal a transition from target-specific to generalized aggression enhancement over 10 days of winning in male mice, which is supported by three stages of plasticity in the ventrolateral part of the ventromedial hypothalamus (VMHvl), a critical node for aggression. Over 10-day winning, VMHvl cells experience monotonic potentiation of long-range excitatory inputs, a transient local connectivity strengthening, and a delayed excitability increase. These plasticity events are causally linked. Optogenetically coactivating the posterior amygdala (PA) terminals and VMHvl cells potentiates the PA-VMHvl pathway and triggers the cascade of plasticity events as those during repeated winning. Optogenetically blocking PA-VMHvl synaptic potentiation eliminates all winning-induced plasticity. These results reveal the complex Hebbian synaptic and excitability plasticity in the aggression circuit during winning that ultimately leads to an increase in "aggressiveness" in repeated winners.

Evaluation of the Strengthening Effects on Prestressed Carbon-Fiber-Reinforced-Polymer-Strengthened Steel Beam Bridges Using Macro-Strain Influence Lines

Effectively evaluating the effectiveness of bridge strengthening is a necessary means to ensure the normal operation of existing strengthened bridges, especially when evaluating the effectiveness of bridge strengthening without interrupting normal traffic. Based on a distributed long-gauge Fiber Bragg Grating (FBG) sensor, this paper derived the macro-strain influence line (MSIL) formula for a simply supported beam bridge under a moving vehicle load, studied the changes in the MSIL at the bottom of the beam under the vehicle load before and after the prestressed CFRP plate strengthening, and proposed a rapid evaluation method for the strengthening effect based on the amplitude of the MSIL as the evaluation index for the strengthening effect. Finally, the prestressed CFRP-strengthened steel beam was tested under the moving vehicle load. The theoretical analysis and the experimental results confirm that under the load of moving vehicles, the macro-strain–time history amplitude of the strengthened steel beams under different prestressed tensioning conditions is different. The amplitude of the macro-strain time history of the strengthened bridge is reduced compared to before strengthening, and the local strengthening effect of the bridge can be monitored by the amplitude change in a single sensor. The change in global stiffness can be evaluated by monitoring the MSIL obtained from multiple long-gauge strain sensors.

Effect of thermal treatments on the microstructure and local mechanical behaviour of a laser beam welded CoCuFeMnNi high-entropy alloy

An equiatomic CoCuFeMnNi high entropy alloy was subjected to laser beam welding and the effect of two post-weld thermal treatments (i.e. solution treatment and direct ageing) was studied. Multiple characterisation techniques were implemented to correlate the local mechanical behaviour (evaluated by direct image correlation) to the microstructural evolution, induced by welding and thermal treatments across the melted zone, the heat affected zone, and the base material. This in turn provided an understanding of the macroscopic mechanical behaviour of welded CoCuFeMnNi plates. Ageing treatment induces strengthening through a nanometric, maze-like structure resulting from spinodal decomposition, without affecting the grain structure. The dendritic microstructure is dissolved by solution treatment, which also activates the recrystallization of the melted zone, thus reducing the residual stresses caused by solidification. The local strengthening produced by spinodal decomposition, and the improved strain hardening capability resulting from grain refinement allow the melted zone to stand out in directly aged and solution-treated conditions, respectively.

Seismic upgrade of a non-code compliant multi-storey steel building: A case study

This study aims to develop a step-by-step design procedure for the seismic upgrade of existing steel buildings based on local strengthening interventions of the connections and the use of conventional X-concentrically bracings (X-CBFs), which are designed to account for both architectural and time/cost-saving constraints. The proposed procedure is applied to an existing non-code-compliant six-storey steel building, which is located in Naples (Italy). Both local and global numerical analyses are performed to investigate the effectiveness of the proposed procedure. The obtained results show that it is possible to decrease by up to 25 % the resistance and stiffness of new X-CBFs if the beam-to-column connections are strengthened to resist the flexural capacity of the connected beams. The pushover-based seismic fragility of as-built and upgraded structures is compared, and the seismic risk reduction is further quantified according to the Italian guidelines for the risk classification of constructions. The variation of seismic risk class induced by designed interventions is evaluated, thus confirming substantial risk mitigation of the upgraded building.

Three-dimensional finite element simulation and reconstruction of jointed rock masses for bench blasting

During the numerical simulation of blasting in jointed rock masses, the accuracy of joint geometric parameters is one of the key factors affecting the numerical results. To facilitate the numerical simulation, most of the previous studies on blasting in jointed rock masses were conducted on regular jointed rocks, which is not conducive to fully revealing the dynamic responses and blast-induced damage characteristics of jointed rock mass. In this study, scanline sampling and borehole sampling were employed to obtain the surface and internal joint structures of the rock bench. To represent the joint geometry, a reconstruction technique for three-dimensional (3D) jointed rock masses in LS-DYNA was proposed utilizing MATLAB code. In the process, the elements on joint surfaces were identified and assigned mechanical parameters of joints to construct the 3D jointed rock model, where the geometrical properties of generated joints obey the statistical distribution obtained from the scanline survey. Taking an open-pit limestone mine as an example, a statistical analysis of the 3D distribution of joints was carried out and used to construct a 3D jointed rock numerical model for bench blasting. Comparisons between the bench slope extracted from the numerical model and the actual joint trace mapping from a rock exposure are performed, and the similarity between the two contour plots of joint orientations reaches 91.6 %. For comparison tests, the bench blasting was simulated by an intact rock model and the jointed rock model. The results indicate that the dynamic responses and blast-induced damage characteristics of jointed rocks are significantly affected by the geometry of joints. Compared with the intact rock model, the presence of joints causes stress concentration and local strengthening of rock damage between adjacent joints, which results in a 30.5 % increase in the damage volume. Furthermore, a field blasting test was conducted to analyze the accuracy of the jointed rock model. The results show that the fragment size distributions obtained from the jointed rock numerical model and the filed test are generally consistent, and the error between them in the proportion of rock fragments with a size of 0 ∼ 100 mm is only 12.8 %. These findings indicate that the proposed reconstruction method of the jointed rock model is considerably robust for characterizing the joint geometry of in situ rock masses and simulating the bench blasting in jointed rock masses.

Decadal‐Scale Variability in the Surface Flow of the Gulf of Maine Coastal Current: The Impact of Changing Climate Conditions on Coastal Circulation

AbstractThe Gulf of Maine (GOM) is one of the most productive and ecologically important marine environments on the planet. The Gulf of Maine Coastal Current (GMCC), which stretches along the western side of the GOM from the Bay of Fundy to Cape Cod, plays an important role in supporting this productivity by transporting nutrients, larvae and dinoflagellates southwestward along the Canadian and New England coastlines. Climate change has led to alterations in GOM ecosystems in recent years: GOM water temperatures have warmed and distributions of marine species have shifted. However, the impacts of the changing climate on the circulation within the GOM, including the path and velocity of the GMCC, have remained unclear. Here, we examine data collected by satellite tracked surface drifters and velocity data collected by the NERACOOS buoy array in order to investigate inter‐decadal changes to the flow of the GMCC. We find that over inter‐decadal timescales, the alongshore surface flow of the GMCC has slowed, particularly in the region southwest of Penobscot Bay. The slowdown observed in the GMCC surface flow is most likely attributed to a local strengthening of the southwesterly winds over the time period of interest.

Effects of V on the microstructure and mechanical properties of HfNbTaTiVx refractory multi-principle element alloys: A combined experimental and computational study

Refractory multi-principle element alloys (RMPEAs) represent a promising class of high-temperature structural materials due to their excellent high-temperature mechanical properties. An important challenge in the application of RMPEAs is achieving a suitable balance between high strength and ambient ductility. Previous investigations have suggested that vanadium (V) element plays a key role in maintaining the high strength and ductility of RMPEAs. Nevertheless, the fundamental mechanisms by which V influences the strength and ductility of RMPEAs remain unclear. To address this issue, a series of HfNbTaTiVx (x = 0.00–1.00) alloys were designed to investigate the effects of V content on the microstructural and mechanical properties of RMPEAs. The results demonstrate that the prepared HfNbTaTiVx alloys are single-phase body-centered cubic (BCC) solid solutions. V addition helps to improve the tensile yield strength of the alloys while concurrently preserving their ductility. The tensile yield strength increases from 729 MPa (x = 0.00) to 997 MPa (x = 1.00) with the increase of V. Impressively, the HfNbTaTiV0.25 alloy exhibits a tensile fracture plastic strain of 21.9%, which surpasses most existing RMPEAs. The increase in yield strength mainly comes from the intensification of local lattice distortion and solid solution strengthening caused by the introduction of V. Furthermore, the addition of V helps to decrease the elastic anisotropy of the alloys, which is advantageous for their processing quality. Overall, this study not only elucidates the role of V in conferring strength and ductility to RMPEAs but also provides valuable insights for the development and industrial application of RMPEAs.

Finite element analysis and optimization design of large vibrating screen based on equivalent static load method

Vibrating screens have wide applications in various industries, ranging from agriculture to coal mining. In recent years, improvement in production have put forward higher requirements on the efficiency of vibrating screens. However, these large screens are prone to fatigue damage, particularly crack formation, over time. The emergence of substantial dynamic inertial forces can be attributed to the considerable body mass of a large vibrating screen. This study analyzed the structural strength of the HZXZ200x300 large vibrating screen, employing finite element simulation to identify the maximum equivalent stress and primary stress distribution. The main frame model of the vibrating screen box was constructed by integrating the equivalent static load and submodule methods. The model transitioned from dynamic response to static optimization under equivalent static and dynamic loads, significantly reducing calculation scale and enhancing optimization efficiency. Equivalent static sub-models were employed for topology optimization, determining the optimal structure for material performance distribution. This process yielded an optimal conceptual model for reconstructing the actual model. The structural strength was further improved by comparing three-dimensional and dynamic local stress relationships post-topological optimization, followed by reinforcing the vibrating screen structure and introducing reinforced bars for increased stability. The study showed that lightweight topology optimization significantly decreased the stress levels and improved the fatigue durability of beams. Local strengthening, accomplished via topology optimization, effectively reduced the maximum equivalent stress to 76.487 MPa, a decrease of 46.8%. The vibrating screen mass also decreased by 225 kg, a reduction of 14.9%. In summary, this study employed structural analysis, topology optimization, and local reinforcement to mitigate stress levels, enhance the fatigue life of a vibrating screen, and reduce its weight. This study offers an effective solution to the dynamic optimization challenges of complex structures.

LOCAL POLITICAL DYNAMICS IN THE GENERAL ELECTION DIRECTLY CONDUCTED TO VOTE FOR DISTRICT HEADS (PILKADA) IN BADUNG REGENCY IN 2005

The general election directly conducted to vote for the regent and vice regent (Pemilihan Kepala Daerah, abbreviated to Pilkada) by the people in Badung Regency in 2005 was the first one. The people’s direct involvement in the local political life moved highly dynamically. The struggle for power by various strengths affected various dimensions of the people’s lives; therefore, it is interesting to investigate the local political dynamics in the Pilkada directly conducted in Badung Regency in 2005 in the perspective of cultural studies. There are three problems formulated in this study. They are (1) what was the dynamics of the Pilkada directly conducted in Badung Regency in 2005 like?; (2) how the relation of strengths affected the local political dynamics in the Pilkada directly conducted in Badung Regency in 2005?; (3) what were the implications and meanings of the local political dynamics of the Pilkada directly conducted in Badung Regency in 2005?&#x0D; The results of the study show that fluctuative changes took place continuously with regard to the form and functions of societal structure. Culturally, the people’s ideology changed from being mono centric into being multi centric. The relation of strengths became segmented into three main strengths forming a new formation of strength referred to as trisula. This led to an institutional configuration, differentiation of power and locality sedimentation, and provided meanings to competition and tolerance, emancipatory, political comodification, adaptive leadership and local democratic cultural strengthening.&#x0D; Keywords: dynamics, local politics, and direct pilkada in Badung Regency

문화도시 사업의 사회적 효과 분석

Korea's cultural city project has been promoted since 2019 by the Ministry of Culture, Sports and Tourism. Although this project has been in progress for four years, there is little empirical analysis of performance or effectiveness. Chuncheon City was selected as a preliminary cultural city in 2019 and then designated as a cultural city in 2020. The purpose of this study is to empirically analyze the social effects of the Chuncheon Cultural City project “Dosiga Salon”. This study established factors at the individual level(cultural enjoyment, happiness, domiciliation factors, awareness of exchange, connectedness), regional level(social capital), and project level(recognition of program effectiveness). In addition, the effect was estimated based on the accumulated experience of the program(frequency or period of program participation). The survey was conducted on 260 space owners, professionals, and residents who participated in this project, and social effects were analyzed through independent sample T-Test and one-way ANOVA. As a result of the analysis, the group that participated in this project frequently or for a long time generally had a higher average score than the group that did not participate, and the results were statistically significant. These results show that the cultural city project is leading to positive changes in local residents. The results were consistent with the goals of the cultural city project: ‘expanding the enjoyment of culture by local residents’ and ‘creating a local cultural foundation and strengthening capabilities’. Based on these results, we proposed the need to establish a mid-term plan for this project, develop community programs, and build social capital.

Innovation, competitiveness, and business ecosystem: determinants of local economic strengthening

This study aims to analyze the influence of innovation, competitiveness, and business ecosystem variables on strengthening the local economy. The development of small businesses as the basis of the people's economy is one of the strategic steps that need to be followed up with concrete steps to increase family productivity, improve the economy, and overcome the problems of poverty, and unemployment. Community business is one of the strengthening of the local economy. This research is field research with qualitative and quantitative approaches to provide a comprehensive explanation. The research sample was MSME business actors in Sukajadi Village, Muaraenim Regency using the purposive sampling method. Data collection techniques are used through surveys, documentation, and questionnaires using Likert scales to assess instruments. Multiple linear regression equations were utilized for the analysis of the data. The results showed that the variables of innovation, competitiveness, and business ecosystem partially or simultaneously affect the strengthening of the local economy. The independent variable affected the dependent variable by 51.2% while the remaining 48.8% was influenced by other variables not described in this study. Innovation, competitiveness, and business ecosystems play a crucial role in strengthening the local economy. These factors are interconnected and have a positive impact simultaneously and reinforce each other. By working together, innovation, competitiveness, and business ecosystems can create a strong sustainable, and inclusive local economic environment at the local level. This not only benefits local businesses but also for communities to become more resilient and able to access more opportunities. This condition supports the improvement of the welfare and quality of life of the community as a whole.

Research on integrated technology of integral aerial building formwork equipment and large tower crane

The integrated aerial building formwork equipment is an independently developed support apparatus by China, which is primarily and importance for the construction of concrete structures in ultra high buildings exceeding 200 m. The novelty of this paper focuses on optimizing and improving the load transmission system and its critical large bearing support structure connecting the tower crane through theoretical analysis and finite element numerical calculation. By obtaining the stress ratio and maximum deformation before and after integrated optimization design, a local strengthening scheme for the tower crane support tube is proposed to simplify the structural connection while significantly reducing self-weight and steel consumption without compromising mechanical performance requirements, thus improving the overall performance of the integrated formwork equipment for aerial building construction.

Methodological Approach to Identify and Expand the Volume of Antimicrobial Resistance (AMR) Data in the Human Health Sector in Low- and Middle-Income Countries in Asia: Implications for Local and Regional AMR Surveillance Systems Strengthening.

Antimicrobial resistance (AMR) is a multifaceted global health problem disproportionately affecting low- and middle-income countries (LMICs). The Capturing data on Antimicrobial resistance Patterns and Trends in Use in Regions of Asia (CAPTURA) project was tasked to expand the volume of AMR and antimicrobial use data in Asia. The CAPTURA project used 2 data-collection streams: facility data and project metadata. Project metadata constituted information collected to map out data sources and assess data quality, while facility data referred to the retrospective data collected from healthcare facilities. A down-selection process, labelled "the funnel approach" by the project, was adopted to use the project metadata in prioritizing and selecting laboratories for retrospective AMR data collection. Moreover, the metadata served as a guide for understanding the AMR data once they were collected. The findings from CAPTURA's metadata add to the current discourse on the limitation of AMR data in LMICs. There is generally a low volume of AMR data generated as there is a lack of microbiology laboratories with sufficient antimicrobial susceptibility testing capacity. Many laboratories in Asia are still capturing data on paper, resulting in scattered or unused data not readily accessible or shareable for analyses. There is also a lack of clinical and epidemiological data captured, impeding interpretation and in-depth understanding of the AMR data. CAPTURA's experience in Asia suggests that there is a wide spectrum of capacity and capability of microbiology laboratories within a country and region. As local AMR surveillance is a crucial instrument to inform context-specific measures to combat AMR, it is important to understand and assess current capacity-building needs while implementing activities to enhance surveillance systems.

Local Strengthening of Reinforced Concrete Frames Using Textile Reinforced Mortar Jackets under Gravity and Cyclic Loadings

Local Strengthening of Reinforced Concrete Frames Using Textile Reinforced Mortar Jackets under Gravity and Cyclic Loadings