Mechanical Analysis Research Articles

Applicability investigation on failure assessment diagram of ASME code section XI - Appendix H for ferritic nuclear piping

The failure assessment diagram (FAD) is a widely used tool for evaluating the fracture acceptance of structural components. In addition to linear elastic fracture mechanics, elastic-plastic fracture mechanics, and limit load analysis, the ASME Code incorporated FAD as an alternative safety evaluation method for flaws in nuclear pipes starting from 2004 edition. This paper conducts a series of finite element elastic-plastic fracture mechanics analyses to establish the specific –based FAD curves considering various loading and geometry conditions for ferritic pipes containing various circumferential flaws. By comparing with the suggested FAD of ASME Code Section XI - Appendix H, it is found that the radius-to-thickness ratio of pipes and the flaw depth influence the applicability of FAD, but with minor effects of crack length. In addition, the effects of material properties between base metal and weld materials on FAD are also discussed. The result of this work could be a reference when applying the FAD to evaluate the flawed piping for nuclear power plants.

Structural Design and Mechanical Analysis of HTS CICC Made From Twisted Stack Slotted-Core Cable

Structural Design and Mechanical Analysis of HTS CICC Made From Twisted Stack Slotted-Core Cable

Does “Going Global” help to restrain enterprises’ financialization: The Belt and Road initiative as a quasi-natural experiment

This paper employs the difference-in-differences (DID) to investigate the impact of “going global” on enterprises' financialization. Baseline estimation shows that the degree of financialization of enterprises participating in the Belt and Road Initiative was lower compared with those not participating in the Initiative. Mechanism analysis reveals that “going global” through Belt and Road Initiative has improved enterprises' profitability of real sector investment and inhibited their motivation of financialization. These findings provide new perspectives for more effectively promoting enterprises to participate in the Belt and Road construction and helping inhibit enterprises’ financialization.

Impact of industrial robot on labour productivity: Empirical study based on industry panel data

This empirical analysis explores the impact of industrial robots on labour productivity using panel data of 17 Chinese industries from 2006 to 2021. The results reveal that the development of industrial robots significantly improves labour productivity; a series of robustness tests validate this outcome. However, the impact of industrial robots on labour productivity varies across industry types. The influence coefficient of the low-density robotics industry is larger than that of the high-density robotics industry. Furthermore, although the scale of industrial robot usage before 2012 was smaller than that after 2012, its effect on labour productivity was more significant. Our findings indicate the possibility of diminishing marginal effect of industrial robots in promoting labour productivity. The mechanism analysis demonstrates that human capital level has a complete intermediating effect between industrial robots and labour productivity. Thus, industrial robot applications can contribute to labour productivity by optimising human capital structure. These findings provide crucial insights for governments and policy makers to improve labour productivity and economic growth.

Molecular basis of hereditary cardiomyopathy: A systematic review

Hereditary cardiomyopathies include a diverse spectrum of myocardial disorders characterized by mechanical and electrical abnormalities, among which hypertrophic cardiomyopathy (HCM) and dilated cardiomyopathy (DCM) are distinguished. This paper dives into the genetic foundations of these conditions, with a focus on mutations in genes encoding sarcomere proteins, thin filament proteins, and calcium homeostasis regulators. The familial aggregation of cardiomyopathies underscores the substantial genetic component, with autosomal dominant inheritance patterns predominant in some cases. Genetic testing and counseling emerge as pivotal tools for early diagnosis, risk assessment, and the formulation of personalized treatment strategies. The integration of genetic insights into clinical management holds promise for improving patient outcomes and reducing disease burden. Further analysis of the molecular mechanisms underlying hereditary cardiomyopathies is critical for identifying novel therapeutic targets and advancing precision medicine approaches. By comprehensively exploring the genetic underpinnings of cardiomyopathies, this paper contributes to our understanding of these complex diseases and highlights the potential for innovative interventions to enhance patient care in the field of cardiovascular medicine.

Adding mechanobiological cell features to finite element analysis of an immediately loaded dental implant.

Finite element analysis (FEA) has been used to analyze the behavior of dental materials, mainly in implantology. However, FEA is a mechanical analysis and few studies have tried to simulate the biological characteristics of the healing process of loaded implants. This study used the rule of mixtures to simulate the biological healing process of immediate implants in an alveolus socket and bone-implant junction interface through FEA. Three-dimensional geometric models of the structures were obtained, and material properties were derived from the literature. The rule of mixtures was used to simulate the healing periods-immediate and early loading, in which the concentration of each cell type, based on in vivo studies, influenced the final elastic moduli. A 100 N occlusal load was simulated in axial and oblique directions. The models were evaluated for maximum and minimum principal strains, and the bone overload was assessed through Frost's mechanostat. There was a higher strain concentration in the healing regions and cortical bone tissue near the cervical portion. The bone overload was higher in the immediate load condition. The method used in this study may help to simulate the biological healing process and could be useful to relate FEA results to clinical practice.

Strengthening-Durable Trade-Off and Self-Healing, Recyclable Shape Memory Polyurethanes Enabled by Dynamic Boron-Urethane Bonds.

Addressing the demand for integrating strength and durability reinforcement in shape memory polyurethane (SMPU) for diverse applications remains a significant challenge. Here we synthesized a series of SMPUs with ultra-high strength, self-healing and recyclability, and excellent shape memory properties through introducing dynamic boron-urethane bonds. The introducing of boric acid (BA) to polyurethane leading to the formation of dynamic covalent bonds (DCB) boron-urethane, that confer a robust cross-linking structure on the SMPUs led to the formation of ordered stable hydrogen-bonding network within the SMPUs. The flexible crosslinking with DCB represents a novel strategy for balancing the trade-off between strength and durability, with their strengths reaching up to 82.2MPa while also addressing the issue of durability in prolonged usage through the provision of self-healing and recyclability. The self-healing and recyclability of SMPU were demonstrated through rapid dynamic exchange reaction of boron-urethane bonds, systematically investigated by dynamic mechanical analysis (DMA). This study sheds light on the essential role of such PU with self-healing and recyclability, contributing to the extension of the PU's service life. The findings of this work provide a general strategy for overcoming traditional trade-offs in preparing SMPUs with both high strength and good durability. This article is protected by copyright. All rights reserved.

Design Method of Cam Steering Mechanism Based on Path Fitting

In order to improve the accuracy of a solar-powered punch card car’s movement on a designated route and reduce positional deviations during its operation, a solar-powered punch card car with a single cam as the steering guidance mechanism was designed. The car adopts a three-wheel structure. The transmission mechanism, steering mechanism, driving mechanism, and regulating mechanism of the car were analyzed. The kinematics model of the car was established and the motion characteristics of the car were obtained. By analyzing the relationship between the steering angle of the car and the curvature radius of its travel route, the front wheel angle of the car at each position was calculated using MATLAB R2020a. This allowed us to establish the relationship between the front wheel angle and the displacement of the steering push rod, which was further converted into the theoretical contour line of the cam. Subsequently, the theoretical contour line of the cam was completed and envelope correction was performed. Finally, through mechanical analysis and experimental verification using a prototype, the results indicated that the single-cam steering guidance mechanism calculated using this fast path fitting method exhibited excellent mechanical performance and a smooth and accurate trajectory, and the traveling path of the theoretical cam contour curve was basically consistent with the actual trajectory route.

Influence of Supercritical CO2 Fracturing Fluid on the Permeability of Shale Reservoir and Mechanism Analysis

Influence of Supercritical CO₂ Fracturing Fluid on the Permeability of Shale Reservoir and Mechanism Analysis

Mechanism Matters: Differential benefits of cold-stored whole blood for trauma resuscitation from a prospective multicenter study.

Resuscitation with cold-stored low-titre whole blood (LTOWB) has increased despite the paucity of robust civilian data. Most studies are in predominately blunt trauma and lack analysis of specific subgroups or mechanism of injury. We sought to compare outcomes between patients receiving LTOWB vs. balanced component therapy (BCT) after blunt (BL) and penetrating (PN) trauma. Secondary analysis of a prospective multicenter study of patients receiving either LTWOB-containing or BCT resuscitation was performed. Patients were grouped by mechanism of injury (BL vs PN). A generalized estimated equations model using inverse probability of treatment weighting was employed. Primary outcome was mortality and secondary outcomes were acute kidney injury, venous thromboembolism, pulmonary complications, and bleeding complications. Additional analyses were performed on non-traumatic brain injury (TBI), severe torso injury, and LTOWB-only resuscitation patients. 1617 patients (BL 47% vs PN 54%) were identified; 1175 (73%) of which received LTOWB. PN trauma patients receiving LTOWB demonstrated improved survival compared to BCT (77% vs. 56%; p<0.01). Interval survival was higher at 6 hrs (95% vs. 88%), 12 hrs (93% vs. 80%) and 24 hrs (88% vs. 57%) (all p<0.05). The survival benefit following LTOWB was also seen across PN non-TBI (83% vs. 52%), and severe torso injuries (75% vs. 43%) (all p <0.05). After controlling for age, sex, injury severity, and trauma center, LTWOB was associated with decreased odds of death (OR .31, p<.05) in PN trauma. However, no difference in overall mortality was seen across the BL groups. Both PN and BL patients receiving LTOWB had more frequent AKI compared to BCT (19% vs. 7% and 12% vs 6%, respectively; p<0.05). LTOWB resuscitation was independently associated with decreased mortality following PN trauma, but not BL trauma. Further analysis in BL trauma is required to identify subgroups that may demonstrate survival benefit. Therapeutic/Care Management, III.

The Micro-Effect of Monetary Policy on the Misallocation of Credit

The structural effects of monetary policy and these effects impact on credit allocation are crucial facets of monetary policy research. This study initially estimates China’s monetary policy based on the GDP growth target and CPI target found in the Chinese Government’s Annual Work Report. Subsequently, it quantifies the extent of credit misallocation among Chinese firms using data from listed companies from the years 2013 to 2022. Finally, we empirically investigate the repercussions of expansionary monetary policy shocks on credit misallocation, focusing on micro-firms. Empirical findings reveal that expansionary monetary policy significantly exacerbates credit misallocation, particularly in underfinanced firms. Mechanistic analysis suggests that a preference for loan size in lending behavior constitutes a major factor contributing to credit misallocation among firms.

How housing burden damages residents’ health: evidence from Chinese cities

BackgroundCurrently, China is steadily pursuing high-quality development and promoting common prosperity, for which residents’ health is a precondition. However, high housing-price-to-income ratios and rent-to-income ratios have already triggered many social problems and have substantially affected people’s work and life. It is of practical significance to examine the relationship between housing burden and residents’ health.MethodsCombining city-level housing price-to-income ratio data and residents’ health data from the China Family Panel Studies, this study employs a binary logit model to investigate the impact and mechanism of housing burden on residents’ physical and psychological health.ResultsOverall, a 1% increase in the housing-price-to-income ratio leads to a 1.2% decrease in physical health and a 1.9% decrease in psychological health. In terms of different psychological state indicators, a 1% increase in the housing price-to-income ratio leads to a 1.1% increase in depression, 1.1% increase in nervousness, 1.4% increase in relentlessness, 1.4% increase in hopelessness, 1.0% increase in a sense of incapability, and 1.4% increase in meaninglessness. According to mechanistic analyses, a 1% increase in the housing-price-to-income ratio leads to increases of 0.6 and 0.7% in the smoking rate and late sleep rate, respectively, while it leads to a 0.9% decrease in the noon nap rate.ConclusionA growing housing burden significantly negatively impacts both the physical and psychological health of residents and increases the possibility of negative emotions. Further investigation revealed that the housing burden damages residents’ health by increasing their likelihood of smoking and sleeping late and decreasing their likelihood of taking a nap at noon, while exercise alleviates the negative impacts of the housing burden on residents’ physical and psychological health. Finally, we also find that housing burdens’ impacts on physical and psychological health differ significantly in terms of gender, age, and educational attainment. From the perspective of improving livelihoods, governments should consider the relationship between housing burdens and residents’ health when formulating livelihood policies. Location-specific and targeted policies should be followed. Additionally, efforts should be made to promote exercise among citizens.

The Nexus between Green Finance and Carbon Emissions: Evidence from Maturity Mismatch in China

Green finance has been widely acknowledged as a pivotal instrument for mitigating carbon emissions. However, few studies have focused on the role of maturity mismatches in promoting carbon emission reduction through green finance. This study aims to develop a composite criterion for green finance and examine the mechanism of how green finance affects carbon emissions via the new perspective of maturity mismatch. It is accomplished by applying a two-way fixed effects model which incorporates provincial data spanning from 2010 to 2020. The empirical evidence suggests green finance plays a significant role in carbon emission reduction, a result that remains robust even after undergoing other tests such as using instrumental variables and alternating econometric models. Furthermore, this effect is particularly pronounced in regions with high degrees of green finance and low energy consumption. Mechanism analysis documents that green finance reduces carbon emissions by addressing maturity mismatch issues faced by green enterprises. Further research finds that green finance can promote the synergy of pollution and carbon reduction; in particular, the effect of maturity mismatch on SO2 reduction is more obvious. Consequently, this study offers practical recommendations for governments, financial institutions, and other relevant policymakers to further propel the advancement of green finance.

An Experimental Study of the Properties of Carbon Fiber/Epoxy Composites Mixed with Rubber Granules

In this research work, the mechanical properties of hybrid composites reinforced with woven carbon fiber mats particulated with natural rubber powders as fillers in the epoxy resin matrix were investigated. The specimens were prepared by the hand-layup process followed by a vacuum bag moulding process. The vacuum moulding reduces the voids or cavities in the hybrid composites. The natural rubber powder was added in different weight proportions (5%, 10%, 15%, and 20%), and carbon fiber is added in 20% for all the specimens. Experiments such as tension testing, flexural testing, water absorption/acid corrosion/base corrosion tests, dynamic mechanical analysis (DMA), and scanning electron microscopic (SEM) analysis were conducted to evaluate the epoxy carbon rubber (ECR) composites. The tensile and flexural test findings demonstrated that the addition of 10% natural rubber particles gave better results as compared with other proportions. The water/acid/base absorption test findings reveal that the ECR composites are not affected by water/acid/base. The DMA teat findings show that ECR composites having 10% natural rubber have higher damping factor, storage, and loss modulus. The SEM analysis shows that ECR hybrid composites with 10% rubber particles contained a uniform distribution of rubber particles over reinforcement, and also, there were no cracks and voids. According to this research findings, ECR hybrid composites with 10% natural rubber particles prepared during the vacuum bag moulding process can be used to prepare aerospace interior components.

Curing characteristics and performance of a bio-based polyurethane engineered sealant with high bonding strength: Effect of R value and chain extender content

Polyurethane (PU) engineering sealants can be used to fill construction joints and pavement cracks with excellent practical results. However, traditional engineering sealants have the disadvantages of poor strength and raw materials that are not environmentally friendly. In this paper, a novel composition system of bio-based polyurethane engineering sealant was developed. The effects of the isocyanate/macroglycol molar ratio (nNCO/nOH, R value) for component A and the contents of amine chain extender (AME) on the curing characteristics and properties of the PU sealant were investigated using a series of experiments. Firstly, the curing process of the sealant was studied by Fourier transform infrared spectroscopy (FTIR) test, surface drying time test and gel time experiments. Secondly, the basic physical properties of the sealant were studied by tensile and hardness tests. And the water resistance of the sealant was judged. Then, the characteristics of molecular movement of polyurethane sealant were analyzed by dynamic mechanical analysis (DMA). The tensile cross-sections of the specimens were observed by scanning electron microscopy (SEM). Finally, the thermal stability of sealants was studied by thermogravimetric (TG) analysis. The results indicated that the material developed in this research can be used as a high-performance engineering sealant in actual projects. The increase in the R value and the decrease in AME content resulted in a longer curing process of the sealant. The rise of R value and AME content was able to raise the tensile strength, bonding strength and hardness of the sealant. The water resistance of the sealant was better. Also, the glass transition temperature (Tg) and storage modulus could also be increased and the thermal stability of the previous stage could be reduced by increasing the R value and AME content. Considering both the performance and construction requirements, the optimum R value and AME contents are recommended to be 2.1 and 1.4%, respectively.

Predictive Modeling for Microchannel Flow Boiling Heat Transfer under the Dual Effect of Gravity and Surface Modification

This paper investigates the heat transfer performance of flow boiling in microchannels under the dual effect of gravity and surface modification through both experimental studies and mechanistic analysis. Utilizing a test bench with microchannels featuring surfaces of varying wettability levels and adjustable flow directions, multiple experiments on R134-a flow boiling heat transfer under the effects of gravity and surface modification were conducted, resulting in 1220 sets of experimental data. The mass flux ranged from 735 kg/m2s to 1271 kg/m2s, and the heating heat flux density ranged from 9 × 103 W/m2 to 46 × 103 W/m2. The experimental results revealed the differences in the influence of different gravity and surface modification conditions on heat transfer performance. It was found that the heat transfer performance of super-hydrophilic surfaces in horizontal flow is optimal and more stable heat transfer performance is observed when gravity is aligned with the flow direction. And the impact of gravity and surface modification on heat transfer has been explained through mechanistic analysis. Therefore, two new dimensionless numbers, Fa and Conew, were introduced to characterize the dual effects of gravity and surface modification on heat transfer. A new heat transfer model was developed based on these effects, and the prediction error of the heat transfer coefficient was reduced by 12–15% compared to existing models, significantly improving the prediction accuracy and expanding its application scope. The applicability and accuracy of the new model were also validated with other experimental data.

Mechanism Analysis and Optimization Design of Exoskeleton Robot with Non-Circular Gear–Pentabar Mechanism

To address the complex structure of existing rod mechanism exoskeleton robots and the difficulty in solving the motion trajectory of multi−rod mechanisms, an exoskeleton knee robot with a differential non−circular gear–pentarod mechanism is designed based on non−circular gears with arbitrary transmission ratios to constrain the degrees of freedom of the R-para-rod mechanism. In this study, the kinematic model of a non-circular gear–five−rod mechanism is established based on motion mapping theory by obtaining the normal motion positions of the human lower limb. An optimization design software for the non-circular gear–five−rod mechanism is developed using the MATLAB 2018b visualization platform, with the non−circular active gear as the sole input variable. A set of ideal parameters is obtained through parameter adjustment and optimal parameter selection, and the corresponding trajectories are compared with human trajectories. The three−dimensional model of the mechanism is established according to the obtained parameters, and the motion simulation of the non−circular gear–five−bar mechanism demonstrates that the mechanism can better reproduce the expected human knee joint motion posture, meeting the working requirements of an exoskeleton knee robot.

Dynamic tensile viscoelastic properties of porcine periodontal ligament.

The periodontal ligament plays a significant role in orthodontic and masticatory processes. To explicitly investigate the effects of dynamic force amplitude and frequency on the dynamic tensile properties of the periodontal ligament, in vitro tensile experiments were conducted using a dynamic mechanical analysis at various dynamic force amplitudes across a wide frequency range. Storage modulus, loss modulus, and loss factor values were measured. A Maxwell constitutive model based on modulus was established to describe the dynamic mechanical properties of the periodontal ligament. The results showed that the storage modulus ranged from 29.53MPa to 158.24MPa, the loss modulus ranged from 3.26MPa to 76.16MPa, and the loss factor values all increased with higher frequencies and higher dynamic force amplitudes. Based on the parameters obtained from the fitting results, it is evident that the short-term response has a more pronounced impact on the elastic response of the periodontal ligament than the long-term response. Increasing the dynamic force amplitude and its frequency amplified the viscous effects of the periodontal ligament and enhanced energy dissipation. The proposed constitutive model further demonstrated that the periodontal ligament acts as a viscoelastic biomaterial. These findings have implications for future research on the periodontal ligament.

Mechanical Analysis and Simulation of Wood Textile Composites

Wood Textile Composites (WTCs) represent a new and innovative class of materials in the field of natural fiber composites. Consisting of fabrics made from willow wood strips (Salix americana) and polypropylene (PP), this material appears to be particularly suitable for structural applications in lightweight construction. Since the threads of the fabric are significantly oversized compared to classic carbon or glass rovings, fundamental knowledge of the mechanical properties of the material is required. The aim of this study was to investigate whether WTCs exhibit classic behavior in terms of fiber composite theory and to classify them in relation to comparable composite materials. It was shown that WTCs meet all the necessary conditions for fiber-reinforced composites in tensile, bending, and compression tests and can be classified as natural-fiber-reinforced polypropylene composites. In addition, it was investigated whether delamination between the fiber and matrix can be simulated by using experimentally determined mechanical data as input. Using finite element analysis (FEA), it was shown that the shear stress components of a stress tensor in the area of the interface between the fiber and matrix are responsible for delamination in the composite material. It was also shown that the resistance to shear stress depends on the geometric conditions of the reinforcing fabric.

Exploring the Evolution Mechanisms of Social Risks Associated with Urban Renewal from the Perspective of Stakeholders

The urban renewal (UR) process involves various stakeholders and related activities, and the various risks arising from this endeavor can affect these stakeholders. Additionally, the impact of adverse factors such as policy discontinuity and inequitable distribution of benefits among stakeholders can easily result in collective tensions or conflicts, as well as the gradual emergence of potential social frictions and confrontations. These social risks (SRs) not only impede the smooth execution of urban renewal projects but also pose challenges to social harmony and stability. Hence, to mitigate and control the SRs in the UR process (URSRs) and ensure the successful implementation of effective and sustainable UR projects, it is of paramount importance to gain a comprehensive understanding of the occurrence and evolution mechanisms of these SRs. Although existing studies have touched upon the influence of stakeholder conflicts on URSRs, there remains a lack of systematic examination of the evolution mechanisms of these risks from the perspective of stakeholder theory. The resulting fragmented and specialized comprehension of URSRs has hindered the effectiveness of risk governance strategies. This study adopts stakeholder theory to analyze the potential sources of risk throughout the entire UR process. By considering the conflicts of interests among stakeholders, a systematic analysis of the evolution mechanisms of URSRs is explored and targeted governance recommendations for URSRs are proposed.