Essential Mechanical Properties Research Articles

Sustainable High-Performance Concrete Using Zeolite Powder: Mechanical and Carbon Footprint Analyses

This study investigates environmentally friendly high-performance concrete (HPC) by partially replacing cement and silica sand with zeolite powder. The replacement levels included 10%, 20%, and 30% for cement and up to 50% for silica sand. The optimal mix achieved 85 MPa compressive strength, 6 MPa tensile strength, and 7.8 MPa flexural strength with a 30% cement replacement, reducing the carbon footprint to approximately 659.72 kg CO2/m3. These findings demonstrate the potential of zeolite powder to enhance sustainability in HPC without compromising essential mechanical properties, promoting eco-friendly practices in construction.

Optimizing Sheet Metal Formation through Advanced Hydroforming Simulation Technique

In this study, we investigate into the simulation of sheet metal hydroforming for crafting the cap of the axle-hub of a tip trailer within our manufacturing facility. This cap serves a crucial role in safeguarding wheel bearings from the detrimental effects of dust, sand, and dirt. The motivation for this work arises from the challenges encountered during the fixation of a conventional dust cap, which often falls off when subjected to pressure or threading, particularly when the tractor is in motion. The innovative approach pursued in this research involves the utilization of lightweight aluminum sheet metal for cap production, owing to its facile formability. The cap design incorporates four evenly distributed holes around its circumference and secures to the flange using screws. Prior to the manufacturing phase, a simulation of the cap-forming process was conducted using ANSYS Model 15, a computer-aided engineering program. The necessary models were crafted in CATIA, a computer-aided design program, streamlining the entire process to enhance efficiency, reduce costs, and minimize manpower requirements. The simulation encompassed three different thicknesses (1 mm, 2 mm, and 3 mm) for two distinct aluminum alloys, namely 1100 and 5652. The objective was to discern the optimal alloy for the forming process. Essential mechanical properties, including ultimate tensile strength, modulus of elasticity, and yield stress, were input into the ANSYS program to accurately reflect the materials' behavior during forming. The outcomes of our investigation revealed that aluminum alloy 5652 outperformed 1100 in terms of formability. The former exhibited a forming pressure of 300.2 MPa, while the latter required 298.3 MPa for the same forming depth (40 mm) across all three thickness variations. Additionally, the study demonstrated that 5652 is not only more efficient but also safer and more resilient than 1100.

Mechanical properties and global warming potential predictions for high-performance concrete through machine learning models integrated with meta-heuristic algorithms

Recent developments in high-performance concrete (HPC) have made it a high-tech material with enhanced durability and properties, and it is a more ecological material with a longer life cycle. Conventional approaches to assessing HPC properties and environmental effects may lack precision in predicting the effects of additional cementitious materials. Adaptive Boosting Algorithm (ADA) and Stochastic Gradient Boosting (SGB) have emerged as promising approaches for predicting HPC properties and environmental effects, offering more accurate and efficient alternative methods. In this study, the ADA and SBG models have been employed to predict the two essential HPC mechanical properties, including compressive and tensile strengths (CS and TS) and Global Warming Potential (GWP) by coupling with meta-heuristic algorithms, namely Stadium Spectators Optimizer (SSO), Golden Jackal Algorithm (GJA), Brown-bear Optimization Algorithm (BOA), and Golf Optimization Algorithm (GOA)‎ for developing hybrid and ensemble prediction approaches. The study assessed the effectiveness of different models for predicting HPC properties and GWP by employing various metrics. The SGSBGG framework showcased remarkable precision and performance compared to other models in the prediction of CS, TS, and GWP. It outshone its counterparts by achieving the highest prediction accuracy, securing R2 values of 0.994, 0.994, and 0.995 for CS, TS, and GWP predictions, respectively. Additionally, it demonstrated unparalleled accuracy with the lowest modeling errors, registering an RMSE of 1.306 for CS, 0.097 for TS, and 4.469 for GWP. Despite the clear superiority of the SGSBGG model, it is noteworthy that the SGSO, as a hybrid model, delivered notably compatible results.

Multi-Objective Robust Design Optimization for Crashworthiness Enhancement of Hybrid 2D Triaxially Braided Composite Tube Using Evolutionary Algorithms.

An innovative optimal design framework is developed aiming at enhancing the crashworthiness while ensuring the lightweight design of a hybrid two-dimensional triaxial braided composite (2DTBC) tube, drawing insights from the mesostructure of the composite material. To achieve these goals, we first compile the essential mechanical properties of the 2DTBC using a concentric cylinder model (CCM) and an analytical laminate model. Subsequently, a kriging surrogate model to elucidate the intricate relationship between design variables and macroscopic crashworthiness is developed and validated. Finally, employing multi-objective evolutionary optimization, we identify Pareto optimal solutions, highlighting that reducing the total fiber volume and increasing the glass fiber content in the total fiber volume are crucial for optimal crashworthiness and the lightweight design of the hybrid 2DTBC tube. By integrating advanced predictive modeling techniques with multi-objective evolutionary optimization, the proposed approach not only sheds light on the fundamental principles governing the crashworthiness of hybrid 2DTBC but also provides valuable insights for the design of robust and lightweight composite structures.

Influence of amine chain extenders on morphology and performances of poly(dimethylsiloxane) based poly(urea‐urethane) elastomers

AbstractThe structure, morphology, and performance of polyurethanes are greatly influenced by the structure of chain extenders. In this study, two types of amine chain extenders, 1,3‐bis(3‐aminopropyl)‐1,1,3,3‐tetramethyldisiloxane (BAPD) and isophorone diamine (IPDA), were utilized in the synthesis of poly(dimethylsiloxane) (PDMS)‐based poly(urea‐urethane) elastomers (PDMS‐PUUs). The mechanical properties, morphology, and in vitro oxidative stability of the as‐prepared elastomers were controlled by altering the ratio of BAPD and IPDA. The results indicate that the overall phase mixing of PDMS‐PUUs improves after incorporating of BAPD into the hard segments. The hard segment, composed of IPDA with a rigid structure, plays a crucial role in maintaining the essential mechanical properties of the PDMS‐PUUs. Furthermore, PDMS‐PUUs based on mixed chain extenders exhibit relatively high boundary diffuseness and boundary thickness. Especially, the PDMS‐PUU sample synthesized from BAPD and IPDA with a molar ratio of 1/1 features the highest boundary diffuseness (0.094) and boundary thickness (0.395 nm), consequently displaying some remarkable properties, including enhanced cyclic tensile properties, superior strain recovery (92.6%), a low modulus (8.6 MPa), and high tensile strength (20.3 MPa). PDMS‐PUUs also exhibit good oxidative stability and biocompatibility, implying that the as‐prepared PDMS‐PUUs are proven to be biostable and capable of long‐term implantation.

Assessment of Some Physical and Mechanical Properties of Ecballium Elaterium (L.) Seeds Grown in Natural Environment

In this study, Several essential physical and mechanical properties of the seeds of the Ecballium elaterium (L.) plant, which grows naturally in Balıkesir province of Turkey and has some medicinal properties, were determined for product processing and similar processes. All properties were evaluated at different moisture states ranging from 11.48% to 22%, and the changes of these properties according to moisture were observed. At an initial moisture content of 11.48%, Ecballium seeds had a length of 4.72 mm, a width of 2.85 mm, a thickness of 2.09 mm, an arithmetic mean diameter of 3.22 mm, a geometric mean diameter of 3.04 mm, a sphericity of 64.45%, and a thousand grain weight of 13.61 g. As a result of measurements conducted on Ecballium seed re-wetted to moisture levels between 11.48% and 22%, it was observed that its bulk density decreased from 501.00 kg m-³ to 468.5 kg m-³ its true density decreased from 965.67 kg m-³ to 870 kg m-³ its projected area increased from 10.60 mm² to 11.51 mm², its rupture strength decreased from 5.08 N/mm-² to 2.98 N/mm-², and its terminal velocity increased from 2.69 m s-1 to 3.06 m s-1.

Assessing Nutritional Characteristics and Bioactive Compound Distribution in Seeds, Oil, and Cake from Confectionary Sunflowers Cultivated in Serbia.

Sunflower seeds are key agricultural commodities due to their nutritional and industrial value. This study aimed to analyze the distribution of targeted bioactive compounds and assess the physical properties across 27 sunflower seed genotypes, including parental lines and F1 and F2 hybrids, cultivated in Serbia. Various analytical techniques were employed to determine the chemical composition and physical characteristics of the seeds. This research revealed significant genetic variability in fatty acid profiles, with differences in polyunsaturated and saturated fatty acid levels among the genotypes. Hybrid seeds displayed variations in 1000-seed weight and bulk density compared to parental lines, which exhibited higher essential fatty acid contents and mechanical properties advantageous for industrial processing. These insights highlight the potential for refining breeding strategies to improve seed quality for specific industrial purposes. Overall, this study emphasizes the critical role of genetic selection in enhancing the nutritional and processing qualities of sunflower seeds, offering valuable perspectives for advancing agricultural and breeding practices.

The method for the estimation of fracture toughness of thin-walled metallic tube considering the effect of crack orientation

Thin-walled metallic tubes are very susceptible to axial or circumferential cracks in harsh environments such as high temperature, high pressure, and severe corrosion, which seriously endangers the service safety of thin-walled tubes. Fracture toughness is an essential mechanical property index for evaluating the service safety of thin-walled metallic tubes, and its special thin-walled structure cannot be tested by using the specimens with standard configuration. In this work, based on the principle of energy density equivalence, the load–displacement and J-integral expressions of thin-walled metallic tubes with axial and circumferential cracks are proposed, and the fracture toughness test method of thin-walled metallic tubes with axial and circumferential cracks is established. Typical zircaloy cladding tubes were selected to complete the fracture test, and the influence of crack orientation on their fracture properties was investigated. The results show that the fracture toughness of circumferential cracks is lower than that of axial cracks, the circumferential cracks also face the risk of fracture failure, and the estimation of fracture properties of the cladding tubes with circumferential cracks cannot be simply replaced by axial cracks.

A review of the interfacial transition zones in concrete: Identification, physical characteristics, and mechanical properties

Interfacial Transition Zones (ITZ) with high porosity are easier pathways for damage initiation and propagation. However, their mechanical performance has hardly been examined owing to the length scale of the microregions, as well as the heterogeneous and opaque constituent properties, which have been increasingly studied in recent years. This study presents a comprehensive review of the ITZ, determining strategies at the meso-micro level, quantitative characterization, and physical features. It focuses on the effects of various casting and material composition factors on the microstructural and mechanical properties of the ITZ, including porosity, thickness, volume, and elastic modulus. The correlations between the microstructures and the essential mechanical properties are discussed in detail. The weak bonding properties of the ITZ can be tailored by the material composition, which changes its internal microstructure, enhances the adhesion of the paste to aggregates, and fills micropores in cement. Several approaches can be employed to achieve this, such as adding minerals, increasing the curing age, and adjusting the water-cement ratio and sand fineness. The content of the weak ITZ can be reduced by optimizing the size distribution and volume fraction of the aggregates. Furthermore, modelling the gradient distribution of the ITZ thickness and elastic modulus is crucial in numerical simulations to enable an accurate investigation of the damage accumulation process in concrete. This study also identifies the challenges in the mechanical behavior of ITZ and serves as an engineering design guide for more advanced fracture-resistant concrete structures.

Impact of micro-indentation load/time and Zinc concentration on the thermo- mechanical characteristics of amorphous Se78Te20Sn2 alloy

We have performed hardness measurement experiments under different loads and loading times by performing micro-indentation marks in the present work. Chalcogenide glasses (ChGs) comprising Se78Te20Sn2 and Se78-xTe20Sn2Znx (where x = 0, 2, 4, & 6) alloys are the subject of micro-indentation tests in this work. We have utilized both micro-indentation and optical microscopic methods to determine Vickers hardness. Thermal glass transition phenomena have been identified through DSC techniques. The modulus of elasticity (E), an essential mechanical property, has been evaluated using established empirical equations. Further, we have studied other mechanical parameters [e.g., minimal micro-void formation energy (E h ), glass’s fragility index (m), micro-void volume (V h ), etc] and the covalent character of the glassy system. Additionally, various physical parameters, including density, molar volume, and compactness, have also been determined. The results emphasize that the different thermo-mechanical parameters investigated in this study achieve their most extreme values at the highest concentration of Zn. However, the energy of micro-void formation within the glassy network of quaternary glasses remains relatively unchanged after the introduction of Zn into the parent STS alloy;

A novel torque application method for tensegrity structures

The torsional resistance of the beam-like tensegrity structure is an essential mechanical property, but there is currently no systematic approach to applying torque to the structure using external force. This article presents a novel torque application strategy to analyze beam-like tensegrity structures. First, the torque that needs to be applied and the initial self-stable configuration are given. Second, the number of iteration steps is set, and the torque is gradually increased by using an arithmetic sequence, and the torque of each step is evenly distributed to the nodes of the acting surface. Third, the current external forces can be calculated by the nodal coordinates and torque, and the stable configuration under the obtained external force will be found based on the form-finding method. This process will be cycled until the specified torque is achieved. Finally, the equilibrium configuration under the set torque will be obtained, and the deformation analysis of the configuration will be carried out to study its mechanical properties. The elastic potential energy errors of the three-bar tensegrity prism unit and the class 2 tensegrity tower are corrected by 2.8198% and 66.9135%, respectively. This method has been proven to improve calculation precision.

Replicating Chromosomes in Whole-Cell Models of Bacteria.

Computational models of cells cannot be considered complete unless they include the most fundamental process of life, the replication of genetic material. In a recent study, we presented a computational framework to model systems of replicating bacterial chromosomes as polymers at 10 bp resolution with Brownian dynamics. This approach was used to investigate changes in chromosome organization during replication and extend the applicability of an existing whole-cell model (WCM) for a genetically minimal bacterium, JCVI-syn3A, to the entire cell cycle. To achieve cell-scale chromosome structures that are realistic, we modeled the chromosome as a self-avoiding homopolymer with bending and torsional stiffnesses that capture the essential mechanical properties of dsDNA in Syn3A. Additionally, the polymer interacts with ribosomes distributed according to cryo-electron tomograms of Syn3A. The polymer model was further augmented by computational models of loop extrusion by structural maintenance of chromosomes (SMC) protein complexes and topoisomerase action, and the modeling and analysis of multi-fork replication states.

Results of a clinical trial of humeral neck osteosynthesis with carbon – carbon composite material

The metals utilized in the production of various implants in traumatology possess all the required mechanical properties. However, these materials are susceptible to oxidation. Carbon-carbon composites, on the other hand, exhibit X-ray transparency and are easily machinable. Thanks to their intricate yet essential physical, mechanical, and chemical properties, they find effective application in osteosynthesis and endoprosthesis procedures for bone structures. The aim of this study is to comparative view of the treatment outcomes for patients with fractures of the proximal part of the humerus by carbon-carbon composite material plates and titanium plates. Materials and methods. In this study, a carbon-carbon composite material plate was conducted osteosynthesis of the proximal part of the shoulder. In the comparison group, a titanium plate was employed. The study group comprised 20 patients, while the comparison group included 15 patients. The analysis of the results was carried out utilizing the Constant–Murley scale and the Quick DASH questionnaire. Results. A comparative study of treatment outcomes between the main and comparison groups revealed a more significant positive treatment effect in the group that underwent osteosynthesis of the humeral neck by a carbon-carbon composite material plate. This effect was observed at the 3-month, 6-month, and 12-month evaluation points. It was characterized by reduced shoulder pain, alleviated dysfunction manifestations, enhanced daily activities, and improved overall quality of life among patients in this group. Conclusions. The analysis of long-term treatment outcomes for proximal humerus fractures, utilizing both carbon-carbon composite material plates and titanium plates, by the Constant–Murley scale and the Quick DASH questionnaire, demonstrated statistically confirmed improvements in shoulder joint function for both treatment methods.

A Quantitative Method for Seismic Robustness of RC Frame Considering Resistance Vulnerability of Column and Storey Drift Ratios

The concept of seismic robustness is proposed by combining the concept of seismic performance and structural robustness. The existing qualitative, quantitative and evaluation methods of seismic robustness are all direct researched on the whole structure, and the influence mechanism of its internal components on the overall seismic robustness is still unclear. It is very important to establish a clear relationship between component design and structural seismic robustness for the structural design, reinforcement design and final evaluation of structural seismic robustness. Based on this, taking the column as the starting point, a quantitative method for the seismic robustness of RC frame by the seismic robustness index is proposed, which takes into account the resistance vulnerability of column and influence of column on the storey drift ratios (SDRs). In which, the resistance vulnerability is represented by the defined control vulnerability coefficient Pimax, and the influence on the SDRs are represented by the storey drift ratio importance coefficients (SDRCs) λ. The method not only reflects the essential mechanical properties of the column, but also reflects the effects brought about by different SALs. The feasibility of the method is demonstrated by numerical examples of two types of failures (assuming single column and two columns failure), and four optimization design proposals are proposed for it. The analysis shows that λ of the target columns to the floor where the target columns located are obviously greater than those on the remaining floors of the target frame. The seismic robustness index R decreases sharply with the increase of the seismic action level (SAL). R is different compare single column failure with two columns failure under 4 SALs. The most effective way to improve the R of the frame under a certain SAL is to retrofit its control column.

A study on improving the performance of cement-based mortar with silica fume, metakaolin, and coconut fibers

Cement mortar is the primary choice for construction due to its widespread usage. However, certain applications demand high-performance cement mortar. In this pioneering study, we explore using agriculture waste products, industrial by-products, and naturally occurring kaolinite clay as potential additives in composite cement. Our research aims to assess these materials' physical and mechanical attributes to ascertain their efficacy in elevating cement performance. To achieve this, we replaced 20% of the cement in the composite with silica-fume and metakaolin, following a precise mix design fraction of 1:1 (binding materials: sand) for the mortar composites. We successfully identified the optimum combination of metakaolin and silica fume through systematic experimentation that maximizes compression strength. Subsequently, we introduced various proportions of coir fibers (ranging from 3% to 15% by weight) into the cement composite to enhance its structural support capabilities. We carefully calibrated the ratio of the water-to-binding material (ranging from 0.35 to 0.6) to maintain the workability of the cement mixtures. Next, we subjected the cement composites to meticulous curing in water for 7 days, 14 days, and 28 days, respectively, to observe their performance over time. Our comprehensive study encompassed the investigation of critical parameters, including moisture content, density, and water absorption, as well as essential mechanical properties such as compressive strength and modulus of rupture. A total of 270 specimens underwent rigorous testing, yielding compelling results. The composite featuring a combination of 10% silica fume, 10% metakaolin, and 6% coconut fibers showcased superior mechanical and physical properties. SEM and EDX studies also showed dense and packed microstructure of mortar samples. These findings showcase the remarkable potential of this specific composite composition as an environmentally conscious and sustainable alternative to enhance cement performance in construction applications. This research advances eco-friendly construction practices by harnessing the strength of waste-derived materials and naturally occurring resources, supporting a more sustainable and resilient approach to infrastructure development.

Dynamics of chromosome organization in a minimal bacterial cell.

Computational models of cells cannot be considered complete unless they include the most fundamental process of life, the replication and inheritance of genetic material. By creating a computational framework to model systems of replicating bacterial chromosomes as polymers at 10bp resolution with Brownian dynamics, we investigate changes in chromosome organization during replication and extend the applicability of an existing whole-cell model (WCM) for a genetically minimal bacterium, JCVI-syn3A, to the entire cell-cycle. To achieve cell-scale chromosome structures that are realistic, we model the chromosome as a self-avoiding homopolymer with bending and torsional stiffnesses that capture the essential mechanical properties of dsDNA in Syn3A. In addition, the conformations of the circular DNA must avoid overlapping with ribosomes identitied in cryo-electron tomograms. While Syn3A lacks the complex regulatory systems known to orchestrate chromosome segregation in other bacteria, its minimized genome retains essential loop-extruding structural maintenance of chromosomes (SMC) protein complexes (SMC-scpAB) and topoisomerases. Through implementing the effects of these proteins in our simulations of replicating chromosomes, we find that they alone are sufficient for simultaneous chromosome segregation across all generations within nested theta structures. This supports previous studies suggesting loop-extrusion serves as a near-universal mechanism for chromosome organization within bacterial and eukaryotic cells. Furthermore, we analyze ribosome diffusion under the influence of the chromosome and calculate in silico chromosome contact maps that capture inter-daughter interactions. Finally, we present a methodology to map the polymer model of the chromosome to a Martini coarse-grained representation to prepare molecular dynamics models of entire Syn3A cells, which serves as an ultimate means of validation for cell states predicted by the WCM.

Reconstruction of Fibrocartilage with Fibrous Alignment of Type I Collagen in Scaffold-Free Manner.

For functional reconstruction of fibrocartilage, it is necessary to reproduce the essential mechanical property exhibited by natural fibrocartilage. The distinctive mechanical property of fibrocartilage is originated from the specific histological features of fibrocartilage composed of highly aligned type I collagen (Col I) and an abundant cartilaginous matrix. While the application of tensile stimulation induces highly aligned Col I, our study reveals that it also exerts an antichondrogenic effect on scaffold-free tissues constructed with meniscal chondrocytes (MCs) and induces downregulation of Sox-9 expression and attenuated glycosaminoglycan production. Modulation of mechanotransduction by blocking nuclear translocation of Yes-associated protein (YAP) ameliorated the antichondrogenic effect in the presence of tensile stimulation. Since MCs subjected to mechanical doses either by surface stiffness or tensile stimulation showed reversibility of YAP status even after a long-term exposure to mechanotransduction, fibrocartilage tissue was constructed by sequentially inducing tissue alignment by tensile stimulation followed by inducing cartilaginous matrix production in a tension-released state. The minimal tensile dose to constitute durable tissue alignment was screened by investigating the alignment of cytoskeleton and Col I after culturing the scaffold-free tissue constructs with various tensile doses (10% static tension for 1, 3, 7, and 10 days) followed by maintaining in a released state for 5 days. Fluorescence-conjugated phalloidin binding and immunofluorescence of Col I indicated that the duration of static tension for more than 7 days resulted in durable tissue alignment for at least 5 days in the tension-released state. The tissues subjected to tensile stimulation for 7 days followed by 14 days in a released state in chondrogenic media resulted in abundant cartilaginous matrix as well as uniaxial anisotropic alignment. Our results show that the optimized tensile dose can facilitate the successful reconstruction of fibrocartilage by modulating the characteristics of matrix production by MCs.

Thermal and physico-mechanical evaluation of some magmatic rocks at Homrit Waggat Area, Eastern Desert, Egypt: petrography and geochemistry

Egypt is characterized by a wide variety of granitic rocks, making it one of the most essential ten countries producing ornamental stones worldwide. The main objective of this article is to study the effect of the chemical and mineralogical variations of the granitic rocks on their thermal expansion behaviors and physico-mechanical properties for use as dimension stones. The assessment of these rocks was performed using two main parameters: the first dealt with the petrographic investigation and chemical analysis for mineralogical and geochemical characterization. The second dealt with some essential physical and mechanical properties (e.g., water absorption, bulk density, and apparent porosity, and compressive strength), and thermal behavior in terms of linear thermal expansion coefficient. Based on the petrographic description, the samples were classified into five types: syenogranite, alkali-feldspar granite, albitized granite, granodiorite, and tonalite. The mineralogical characterization exhibited variable proportions of quartz and feldspars (plagioclase and alkali-feldspar), in addition to accessory minerals such as titanite, zircon, rutile, and iron oxide-based minerals. The thermal investigation showed insignificant changes in the thermal coefficient values and the thermal strain up to 100 °C as it did not exceed 0.049%, which indicates that they can be installed in places of high-temperature conditions. The physico-mechanical properties revealed that the water absorption ranged from 0.14 to 0.52%, the bulk density ranged from 2590.42 to 2748.23 kg/m3, and the compressive strength ranged from 314.17 to 628.75 kg/cm2. These results indicate that the studied granites could be acceptable for interior (indoor) and light-duty exterior purposes such as building cladding.

Simulation of Load–Slip Capacity of Timber–Concrete Connections with Dowel-Type Fasteners

Quality assessment of stiffness and load-carrying capacity of composite connections is of great importance when it comes to designing timber–concrete composite structures. The new European regulation intended explicitly for timber–concrete structures has made a significant contribution to this field, considering that until today there was no adequate design standard. Due to the proposed general expressions for determining the stiffness and load-carrying capacity of composite connections made with dowel-type fasteners, which are incapable of describing most of the commonly applied fasteners, engineering, and scientific practice remained deprived of a quality assessment of the essential mechanical properties of the connection. In order to overcome this problem, this paper proposes a numerical model of the connection suitable for determining the whole load–slip curve, allowing it to estimate the stiffness and load-carrying capacity of the connection. The model was developed by considering the non-linear behavior of timber and fasteners, which is determined through simple experimental tests. For the numerical model validation, experimental tests were carried out at the level of the applied materials and on the models of the composite connection. Through numerical simulations, analysis of obtained results, and comparison with experimental values, it can be confirmed that it is possible to simulate the pronounced non-linear behavior of the timber–concrete connection using the proposed model. The estimated values of stiffness and load-carrying capacity are in agreement with the conducted experimental testing. At the same time, the deviations are much less than the ones obtained from recommendations given by the new regulation. Additionally, apart from evaluating the value and the simulation of the complete curve, it is possible to determine local effects, such as the crushing depth in timber and concrete, the fastener’s rotation, and the participation of forces in the final capacity of the connection.

Implementation of ensemble Artificial Neural Network and MEMS wireless sensors for In-Situ asphalt mixture dynamic modulus prediction

Dynamic modulus is an essential mechanical property for pavement structural condition assessment yet obtaining the in-situ dynamic modulus of asphalt mixture efficiently and accurately has never been easy. With the development of sensing technology, a type of Micro-Electromechanical Sensor (MEMS), SmartRock, has been applied in pavement monitoring because of its convenience and high efficiency; but interpreting the collected data as useful engineering information becomes a new challenge. This paper aims to present a data processing algorithm for sensing data in pavement engineering and develop a dynamic modulus predictive model based on the ensemble artificial neural network (ANN) model using SmartRock sensing data. Five asphalt mixtures were tested by the uniaxial dynamic modulus test, and one of the 5 mixes was also used in the third-scale model mobile load simulator (MMLS3) test. SmartRock sensors were installed in the specimens to collect the mechanical response during the tests. The empirical mode decomposition (EMD) method was used for data preprocessing. Dynamic modulus test data, in combination with a small portion of early-stage MMLS3 sensing data, were used as the training dataset, while the remaining MMLS3 data were used as the testing dataset. The results show that the ensemble ANN model is feasible and robust in predicting the dynamic modulus of the asphalt mixture in the MMLS3 test. The parametric analysis shows that the ensemble ANN model has reliable stability. Future studies are recommended to expand the database with more material variety and loading conditions for model verification.