Integral bridge abutment with composite dowels: structural scheme and failure patterns

This paper presents a novel integral abutment design incorporating a composite dowel girder and H-shaped steel pile abutments to enhance load-bearing capacity and construction efficiency. Numerical analysis is conducted to investigate the failure modes, load-transfer mechanisms, and ultimate bearing capacity of the integrated abutment joint. A parametric study examines the influence of key factors, including steel girder web thickness and the reinforcement ratio of the deck and abutment, on structural performance. Results indicate that abutment failure is primarily attributed to concrete compression failure beneath the steel girder. Based on the findings, a formula for predicting the ultimate bearing capacity of the integrated abutment joint is proposed. Under the same steel girder depth and bottom plate width, the steel consumption of the integral abutment proposed in this work is reduced while the section has a slightly higher bearing capacity compared that of the traditional I-shaped steel girder

Influence of Silicon Nanosheet (SiNS) on the Toughness of Biphasic Calcium Phosphate (BCP) Composites

Recent developments in the field of replacing and generating human tissues have led to a renewed interest in finding alternative materials or composites that enhance the development of these technologies. Therefore, the main goal of the current study was to investigate the effect of adding a nanomaterial with a two-dimensional structure called silicene, which is also known as silicon nanosheet (SiNS) on among the best leaders in biomaterials which are HA and TCP. This investigation has examined the fracture toughness property and flexural strength to explore the importance of adopting the nanomaterials. Through this paper, silicene has been synthesised using chemical reactions and added in various weight ratios of (1,3, and 5) % to BCP composites which are produced with various weight ratios of HA and TCP. Based on the findings, adding SiNS by a percentage ranging from 1% to 3% to the BCP composites increased their toughness, and flexural strength from 33 to 87.64 %, and 15 to 60 % respectively. However, as some percentages climbed and others fell in toughness or flexural strength, the results of the samples containing 5% of SiNS started to differ somewhat. This is due to that the filler (SiNS) has the capacity to prevent cracks from growing while also preserving crystalline tissue, which makes it a crucial defence against fracture propagation. This increase gave sufficient motivation to adopt this composition and addition in biomedical applications

Experimental and theoretical study of used GFRP I-profile composite columns

Glass Fiber Reinforced Polymer (GFRP) is a promising alternative to steel due to its high strength, lightweight properties, corrosion resistance, and low maintenance requirements. This study examines the effect of internal GFRP I-sections on the axial load capacity and fire resistance of reinforced concrete (RC) columns. The experimental program consisted of two groups: the first group, conventional RC columns, with one exposed to 500°C for 90 minutes and the other unheated, and the second group, GFRP I-section reinforced columns, similarly tested under fire and control conditions. Results show that GFRP-reinforced columns exhibited a 17% higher axial capacity than conventional RC columns. However, fire exposure reduced the axial strength of GFRP-reinforced columns by 39% compared to unheated specimens and by 14% compared to conventional RC columns. Theoretical axial load capacities were calculated using design codes, and finite element analysis (FEA) validated the experimental results. Additional parameters, including concrete strength, steel yield strength, reinforcement ratio, and GFRP section properties, were analyzed. The strong correlation between experimental, theoretical, and numerical results provides a foundation for developing practical design guidelines for GFRP-reinforced composite columns

Application of perforated PEEK framework for improving strength of a bases of removable complete denture for maxilla

The paper presents the results of computer simulation of a hybrid removable complete dentures (RCD) of a maxilla and analysis of its stress–strain states (SSSs) under typical operational loads. For improving their strength and stiffness, it was proposed to reinforce a base made of polymethylmethacrylate (PMMA) with a perforated framework (technological holes for enhancing adhesion) made of polyetheretherketone (PEEK). In total, the SSS for 10 different models were analyzed, simulating the presence or absence of a reinforcing framework as well as its perforation, location in the base, adhesion between the components, and the deformation of the alveolar ridge. The key difference of the conducted computer simulation was the application of a virtual support of the RCD. Its deformation imitated changes in the alveolar ridge height, as well as the presence of more rigid areas corresponding directly to both alveolar ridge and a torus. The SSSs for the FE-models were calculated by the finite element method using the ‘ABAQUS’ software package. The effect of the PEEK framework position on the mechanical properties of the RСD was assessed. It was shown that the main reason for the base’s failure was its bending under the applied loads. However, the load-bearing capacity of the RСD could be increased by 20–40% by embedding of the PEEK framework as an additional layer of the base dome. The effect of variation in the base support conditions, simulating the degradation of the alveolar ridge caused by the bone tissue resorption, was analyzed. It was found that the load-bearing capacity of the RСD could vary within 10% in such cases. The perforation in the PEEK framework did not reduce significantly the mechanical properties of the RСD, but its adhesion to the PMMA base exerted a decisive effect on the operational performance

Flood-induced load effects on real-scale structures: a 3D multilevel dynamic analysis

In this work, the structural behavior of masonry buildings under flash flood actions is analyzed by using a novel 3D multilevel fluid/structure model. The proposed numerical framework consists of a macro-scale model based on the computational fluid dynamic, able to simulate the dynamic free-stream flow of a fluid impacting rigid solids and a meso-scale structural model that employs a coupled damage-plasticity approach to describe the nonlinear behavior of the masonry buildings, subjected to the fluid dynamic pressure extracted by the macro-scale fluid analysis. The integrated model was employed to assess the fluid-structure interaction effects on the global structural response, in terms of load-carrying capacity and damage patterns, of a real-scale masonry structure subjected to flood-induced loading conditions. Finally, a parametric analysis is performed in order to understand the influence of the fluid inlet velocity and water depth on the failure mechanisms of the structure. The results highlight the good numerical capabilities of the proposed multilevel model, establishing it as a valuable numerical tool for the structural vulnerability assessments under flood actions

Assessment of mechanical, fracture and thermal properties of epoxy nanocomposites reinforced with low-concentration nano Boron Carbide (B4C)

This study investigates the effects of low concentration (0.1-0.4 wt.%) nano-boron carbide (B4C) reinforcement on the mechanical, thermal and fracture properties of epoxy nanocomposites. The nanocomposites were prepared via solution casting using ultrasonication to ensure proper dispersion of the nanofiller. The characterisation included Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), tensile, flexural, impact and fracture tests. Results showed significant enhancements in mechanical properties. Tensile strength peaked at 31.2 MPa (71% improvement) for 0.3 wt. % B4C, while modulus increased steadily to 1400 MPa (33% improvement). Flexural tests showed a progressive enhancement in bending strength, exhibiting 70.46 MPa (50% improvement) at 0.4 wt. % B4C. Impact strength surged by 62% at 0.4 wt. % and fracture toughness increased steadily, exhibiting 70% improvement. Thermal analysis revealed a higher glass transition temperature (Tg) and improved stability with B4C addition, attributed to restricted polymer chain mobility. SEM images showed improved fracture resistance, with rougher surfaces and smaller cleavage planes indicating effective energy absorption. Finite element (FE) simulations validated experimental tensile and flexural results, with variations within 15%. Statistical analysis confirmed all improvements were significant (p < 0.05)

Very High Cycle Fatigue (VHCF) of notched specimens: a review

A large number of mechanical components are subjected to fatigue loading beyond 106 cycles. The VHCF behaviour of smooth specimens has been extensively investigated in the recent years, even if more efforts are necessary to reveal the mecahnism governing failures. On the other hand, the influence of notches in the VHCF regime remains relatively unexplored. In the present review, the available studies on the VHCF behaviour of notched components have been analysed and compared. The review highlights that  multiple approaches for accounting for the stress concentration introduced by notches are available in the literature and that notches alter the failure mechanisms compared to smooth specimens. In general, a model for the design of complex structures against VHCF failures and with notches/geometric discontinuities is missing, and more experimental data for different materials are to be obtained to prove the validity of the approaches already available in the literature or employed for the High Cycle Fatigue (HCF) life range. Moreover, since the ultrasonic fatigue testing machines are mainly used for the tests, different definitions for the stress concentration factors have been found in the literature, since, with these types of tests, the stress distribution within the specimen depends on the wave propagation and on the resonance condition

Influence of contact interaction character on residual stresses arising over damaged area in composite plate

New data concerning the values of residual stresses that arise as a result of the contact interaction of a spherical indenter and a flat surface of composite plate have been obtained. The studies are performed for both static indentation and impact influence of a spherical indenter into a flat surface of coupons made of carbon fibre reinforced polymer with cross-ply stacking sequence. The high-quality interference fringe patterns, generated by through hole drilling in contact interaction zone, which are essential for residual stress deriving are visualized and quantitatively processed both inside and outside the contact dimple. The distributions of residual stresses obtained during static and impact contact interaction, which leads to the appearance of dimples of almost the same diameter, are compared. A comparison of the values of the principal residual stress components corresponding to the contact interaction of similar composite plates with a spherical impactor of different diameters for the same impact energy is presented. Several factors have been identified that relate the decrease in the residual strength of damaged specimens to the values of the residual stress components. Evaluation of the influence of coupon’s thickness as well as an impact energy level on the residual stress values inherent in the vicinity of contact dimple is presented

A study on the crack presence effect on dynamical behavior of higher-order Quasi-3D composite steel-polymer concrete box section beams via DQFEM

This paper presents a dynamic and critical buckling analysis of the presence of a crack of steel-polymer concrete composite beams modelled using a refined quasi 3D beam theory. The beam model is a hollow steel box section filled with a composite concrete material. The presence of the crack is assumed on both inner concrete core and outer steel layer box, incorporating its effects into the mechanical behavior of the beam. The governing equations for the box beam are derived using the Differential Quadrature Finite Element Method (DQFEM) combined with Lagrange’s principle. The study investigates the natural frequencies and critical buckling loads of steel-polymer concrete composite beams under various crack location and crack depth. Validation is performed by comparing the results with numerical methods and experimental results available in the literature, demonstrating high accuracy. The findings of this research provide valuable insights into the dynamic and stability behavior of box-section beam with composite infill, offering practical guidelines for the design of material-based structures in engineering applications

Predicting the strength of 3D-printed conductive composite under tensile load: A probabilistic modeling and experimental study

Conductive PLA is an innovative composite material that combines the ecological benefits of polylactic acid, a biodegradable thermoplastic, with electrical conductivity properties. Usually used in additive manufacturing for its ease of printing and low environmental impact, PLA remains an insulator, which limits its applications in the electrical field. To overcome this limitation, conductive fillers such as carbon nanotubes or carbon black are being added, opening the way to new functional uses. This study focuses on a specific composite: carbon black-filled PLA (PLA-CB). This material combines the qualities of traditional PLA with enhanced conductivity thanks to the carbon black particles. To assess its performance, a number of mechanical tests were carried out, including tensile tests on samples manufactured by 3D printing using the FFF process. The study focused in particular on the influence of crosshead speed and the impact of different notch shapes on the material's properties. To analyze the durability of PLA-CB, a probabilistic model based on the two-parameter Weibull distribution was used to assess the risk of failure under different conditions. Reliability curves were also established to better understand the tensile stress and strain at break of the material. This approach could also be applied to other 3D-printed polymers to refine their analytical and numerical modeling