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• Effect of minimal surface-lattice core topological features on the impact properties of a sandwich structure. • Cell size and relative density of minimal surface-lattice core show exponential growth with impact properties of sandwich structures. • The high shear resistance of periodic primitive TPMS topology contributed to improved perforation limit. • Stochastic and spinodoid-based lattice sandwich panels are damage tolerant. Recent advancements in 3D printing technologies have made it possible to fabricate intricate lattice architectures with high precision. These lattices can now be utilized to design lightweight sandwich structures that serve multiple functions. To enhance the impact loading performance of these structures, it is crucial to understand how the lattice's topological properties, particularly those with minimal surface attributes like periodic or stochastic Primitive and Gyroid triply periodic minimal surfaces (TPMS) and spinodal-like stochastic cellular materials, associate with the mechanical properties of sandwich structures while keeping the skin thickness fixed. Thus, this paper explores the low-velocity impact behavior of various sheet/shell-based minimal surface-latticed cores of sandwich structures with woven composite skins. The elasto-plastic-damage numerical simulations consider lattice core periodicity, randomness, and anisotropy while keeping the relative density constant. Core lattice randomness and anisotropy are designed using the Gaussian Random Field (GRF) method for spinodal-based stochastic cellular materials and stochastic TPMS. The simulation results showed that the periodic Primitive-lattice core exhibits high out-of-plane shearing strength, enabling the sandwich structure to demonstrate the highest perforation limit. GRF spinodal-based core achieved the highest peak load due to its anisotropic mechanical properties. However, the post-yielding bending of the lattice sheet limited its ability to resist perforation, and absorb and dissipated energy. Interestingly, the stochastic Gyroid TPMS topology, with its inherent densely-distributed microstructure, showed high sensitivity to loading rate, resulting in enhanced energy absorption and dissipation of the sandwich structure. These findings offer valuable insights for optimizing multifunctional sandwich structures with superior impact performance and their design for additive manufacturing. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • Pyramidal lattice structures (PLS) with I-shaped struts were 3D printed via DLP. • The utilization of I-shaped struts led to an increase in energy absorption of up to 68%. • Lateral buckling of the lattice struts was observed in the tailored PLS. • The measurements and observed collapse modes were in good agreement with FE predictions. • Specific cross-sectional designs can achieve enhancements in strength of up to 93%. This study examines the compressive response of geometrically tailored pyramidal lattice structures composed of struts with I-shaped cross-sections. Geometrically tailored pyramidal lattices with micro-scale features are 3D printed using the Digital Light Processing (DLP) technique, and their effective elastic modulus, collapse strength and energy absorption capacity are experimentally evaluated under quasi-static compressive loading. Furthermore, detailed non-linear finite element (FE) calculations are performed to examine underlying collapse mechanisms and explore the vast design space offered by the proposed geometrical tailoring scheme. Both the experimental and numerical results show that the geometrically tailored lattice structures outperform conventional pyramidal lattices of equal weight in terms of elastic modulus (+24 %), collapse strength (+21 %) and energy absorption (+68 %). Notably, these strength improvements are attributed to lateral buckling that prompts the I-shaped struts to bend sideways during collapse. Specific cross-sectional designs demonstrate remarkable enhancements in strength and energy absorption, reaching up to 93 % and 161 %, respectively, differentiating them significantly from conventional designs. [ABSTRACT FROM AUTHOR]

Sulfide stress cracking (SSC) is a leading cause of failure in sour service environments, where the presence of wet hydrogen sulfide (H 2 S) causes hydrogen embrittlement and significantly influences the performance and lifespan of casing and tubing pipes. This work presents a numerical investigation on predicting the onset and growth of SSC in a sour environment using a coupled deformation–diffusion phase-field finite element framework, which incorporates the role of sub-surface hydrogen concentration due to H 2 S exposure and mechanical loading effects on the crack growth response. The numerical results agree with the experimental data from the notched slow strain rate testing performed on high-strength low alloy steel (HSLA) in a sour environment at room temperature. Recently, the oil and gas industry has been heading towards unconventional gas well applications that expose crucial parts of a well construction, such as production casings, to high internal pressures and a sour environment. To simulate such conditions, a numerical study is conducted that examines the onset and growth of SSC in pre-notched pressurized pipes subjected to H 2 S exposure. The geometry and boundary conditions used for the pre-notched pipes adhere to the API 579 standard for fitness for a service assessment of equipment containing identified flaws or damage. The findings of this comprehensive numerical investigation provide valuable insights into the effectiveness of a coupled phase-field approach for SSC and demonstrate its potential as an engineering tool for structural integrity assessments that consider environmental effects. • Application of a deformation-diffusion phase-field approach to predict SSC. • Accurate prediction of strength reduction due to SSC. • Influence of H 2 S exposure on crack growth response. [ABSTRACT FROM AUTHOR]

To create a human-like skin for a robotic application, current touch sensor technologies have a few drawbacks. Electrical Impedance Tomography (EIT) is a candidate for this application due to its applicability over complex geometries; nevertheless, it has accuracy concerns. This study employs artificial neural networks (ANNs) to investigate the accuracy and capability of EIT-based touch sensors. A finite element (FE) model is utilized to solve the forward EIT problem while simultaneously determining the system's comprehensive mechanical response. The FE model is comprised of a polyurethane (PU) foam domain, a conductive spray layer and a set of sixteen electrodes. To replicate the process of touching the sensor body, a punch of varying diameters and touch forces is utilized. The mechanical response of the sensor body is modeled using the hyperfoam material model calibrated through experimental uniaxial and shear test data, while the electric conductivity of the sprayed skin surface is obtained experimentally as function of applied strain. The viscoelastic behavior of the PU foam material is also obtained experimentally. These experimental data were implemented in the FE model through user subroutines to model the mechanical and electrical properties of the sensor in the EIT forward problem. The traditional EIT inverse problem image reconstruction was replaced utilizing ANNs as an alternative to extract mechanics based parameters. The ANNs were created to predict the spatial coordinates of the touch point, and they were proven to be extremely accurate. Using the EIT voltage readings as input, the ANNs were utilized to forecast the system's mechanical behavior such as contact pressure, contact area, indentation depth, and touching force. • Coupled electro-mechanical finite element model for solving the EIT forward problem. • Representative material model for Polyurethane (PU) foam based on compression and shear tests. • Relation between mechanical stretch and electrical conductivity incorporated in the FE model. • Detailed mechanical behavior of the sensor obtained through the model for multiple touch scenarios. • Artificial Neural Networks (ANNs) used to predict touch location and mechanical behaviors. [ABSTRACT FROM AUTHOR]

• An initial yield surface is established and proposed for cellular materials. • Five loading cases are considered to evaluate the performance of the yield surface. • Five sheet-based triply periodic minimal surface lattices are investigated. • The proposed yield criterion shows accurate yielding predictions for all cases. Triply periodic minimal surfaces (TPMS), which are a class of architected cellular materials, have attracted significant attention lately, due to their prevailing mechanical, electrical and chemical properties, to name a few, and due to the advancements in additive manufacturing technologies that make it possible to print such materials. However, simulating the elastic-plastic mechanical behavior of structural systems (e.g., beams, plates, cores of sandwich panels, structural systems with various levels of geometric complexity) that are latticed with thousands of TPMS lattices are computationally expensive to model explicitly, and hence the need to develop accurate yield surfaces in order to capture their plastic behavior in a homogenized approach. In this work, a generalized initial yield criterion is proposed for sheet-based TPMS lattices, which incorporates the Lode parameter L. The initial yielding of five different sheet-based TPMS lattices are investigated in five different loading conditions. These lattices are Schoen's I-WP (IWP-s), Gyroid (GYR-s), Diamond (DIA-s), F-RD (FRD-s) and Primitive (PRIM-s). The proposed yield criterion accurately predicts the initial yielding of all these lattices in all the loading conditions considered, outperforming other yield criteria currently proposed in literature. [Display omitted] [ABSTRACT FROM AUTHOR]

• The use of carbon allotropes-MXenes composites (CAMCs) as nanofillers in polymer coatings is surveyed. • CAMCs synergistically enhanced the nanofiller and reinforcement properties of carbon allotropes and MXenes. • CAMCs fill the surface micropores and cracks and avoid/delay the diffusion of corrosive species. • The CAMCs formulations manifest magnified durability as well as anticorrosive potential and excellent dispersibility. • CAMCs are chemically and thermally very stable and can be used for high-temperature practices. Carbon allotropes, especially CNTs and GO, and MXenes are well-known for their filler and reinforced properties in polymer coatings. They fill the surface micropores and cracks of rapture coating structures and avoid the diffusion of corrosive species. They also avoid the direct attack of corrosive species by delaying their diffusion rate. However, carbon allotropes and MXenes manifest poor dispersibility as well as interfacial interactions that limit their use. Recent studies suggest that a suitable combination of carbon allotropes and MXenes (CAMs), synergistically enhanced their reinforcement property. The CAMs formulations manifest magnified durability as well as anticorrosive potential. As CAMs are chemically and thermally very stable, they can be used to formulate effective anticorrosive polymer-based coatings for high temperature application. This article aims to describe the challenges and opportunities of using CAMs as fillers in polymer coatings. The mechanism of reinforcement has also been reported along with future directions. [ABSTRACT FROM AUTHOR]

Owing to the advancements in additive manufacturing and increased applications of additively manufactured structures, it is essential to fully understand both the elastic and plastic behavior of cellular materials, which include the mathematically-driven sheet lattices based on triply periodic minimal surface (TPMS) that have received significant attention recently. The compressive elastic and plastic behaviors have been well established for many TPMS latticed structures, but not under multiaxial loading. Furthermore, TPMS lattices are computationally expensive to model explicitly when used in latticing various structures for enhanced multi-functionality, and hence the need to develop accurate yield surfaces in order to capture their plastic behavior in a homogenized approach. The majority of previous yield surfaces developed for cellular materials originate from cellular foams, and limited attempts has been made to develop yield surfaces for TPMS lattices. In this study, a numerical modeling framework is proposed for developing the initial yield surface for cellular materials and is used to develop the initial yield surface for Schoen's IWP sheet-based TPMS cellular lattices. The effect of different loading conditions on the effective yield strength of the IWP sheet-based (IWP-s) TPMS lattice is numerically investigated, based on a single unit cell of IWP-s under fully periodic boundary conditions, assuming an elastic-perfectly plastic behavior of the base material, for relative densities (ρ ‾) ranging from 7% to 28%. In order to account for different loading conditions, the stress state is characterized in a generalized fashion through the Lode parameter (L). The effect of L is studied over a range of mean stress values (σ m) to understand the effect of both L and σ m on the effective yield strength. An initial yield surface is developed incorporating the effect of L , σ m and ρ ‾ , and is validated numerically showing rather good agreement. In the 3D principal stress space, the shape of the yield surface for the IWP-s lattice resembles the shape of a cocoa pod. [Display omitted] • Extensive numerical finite element simulations on Schoen's IWP triply periodic minimal surface. • An initial yield surface is established and proposed for cellular materials, accounting the third deviatoric stress invariant J 3 , through the incorporation of Lode parameter L. • The initial yield surface is validated at three different loading cases, and is compared to other three well established yield surface for cellular materials. • Proposed yield surface has predicts the initial yielding of IWP-TPMS markedly well. [ABSTRACT FROM AUTHOR]

• Enhanced flexural properties of four point bend (4 PB) beam specimens through relative density gradation and hybridization based on TPMS topologies. • Strategies for gradation and hybridization deduced through stress state in 4 PB beam. • Hybridization and relative density gradation schemes is accomplished based on level-set functions of stretching-dominated TPMS sheet-based lattices. • Numerical results are validated through 4 PB testing on additive manufactured beams. • Enhanced flexural stiffness achieved by combining relative density gradation and hybridization with several different TPMS topologies. Due to the recent boom in digital design for additive manufacturing and 3D printing, there has been a significantly growing interest in latticed structures for light design and improved mechanical properties. However, the focus in the literature has mostly been on compressive mechanical properties of uniformly latticed structures with little emphasis on flexural properties of latticed-beams that are functionally graded and hybridized with different lattice topologies. Therefore, this paper aims to explore the effect of lattice relative density gradation and hybridization on the specific flexural properties of prominent sheet-based triply periodic minimal surfaces (TPMS) cellular four-point loaded beams. First, the effective elastic properties of the cubic porous topologies are evaluated computationally to converge to certain sheet-based TPMS cellular structures capable of providing high flexural properties. Schwartz primitive (P) revealed high stiffness to shear loading, meanwhile, the F-Rhombic Dodecahedron (FRD) showed better resistance to uniaxial loading, and the Diamond (D) showed well-combined uniaxial and shear moduli. The selected four-point bend (4 PB) latticed-beams are functionally graded following a bilinear pattern and hybridized through the span of their length inspired by the shearing force and bending moment diagrams arising in the 4 PB beam, in view of the effective elastic properties of the TPMS topologies. The additively manufactured AlSi10Mg uniform, functionally-graded, and hybridized latticed-beams are tested in four-point bending and the results are compared with the finite element results. Both the experimental and numerical outcomes show good agreement within the elastic-plastic regime. From experimental results, it is found that functional grading and hybridization can considerably enhance the specific flexural modulus of sheet-based TPMS latticed-beams. Also, relative density gradation within the four-point bend specimens proved very essential in deflecting crack growth thereby retarding the final failure, meanwhile hybridization is conveyed to mitigate shear-band failure. Combination of functional gradation and hybridization on the latticed-beams resulted in a significant increase in the specific flexural stiffness. Therefore, this study provides guidelines on how to enhance the flexural properties of lightweight beams through lattice functional grading and hybridization. [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract: Ductile failure experiments on a double notched tube (DNT) specimen subjected to a combination of tensile load and torque that was applied at a fixed ratio is presented. The experimental results extend those in Barsoum and Faleskog (2007a) down to zero stress triaxiality. A new and robust evaluation procedure for such tests is proposed, and a simple relation for the equivalent plastic strain at failure for combined normal and shear deformation, respectively, is developed. Tests were carried out on the medium strength medium hardening steel Weldox 420, and the high strength low hardening steel Weldox 960. The experimental results unanimously show that ductile failure not only depends on stress triaxiality, but is also strongly affected by the type of deviatoric stress state that prevails, which can be quantified by a stress invariant that discriminates between axisymmetric stressing and shear dominated stressing, e.g., the Lode parameter. Additional experiments on round notch bar (RNB) specimens are recapitulated in order to give a comprehensive account on how ductile failure depends on stress triaxiality, ranging from zero to more than 1.6, and the type of stress state for the two materials tested. This provides an extensive experimental data base that will be used to explore an extension of the Gurson model that incorporates damage development in shear presented in Xue et al. (2013) (Part II). [Copyright &y& Elsevier]

Abstract: Experiments on double notched tube specimens subjected to tension and torsion were conducted by Barsoum and Faleskog (2007) [8,9]. In this study a complementary experimental investigation was conducted on tensile round circumferentially notched bar specimens. The results from the current study were compared with the results from the double circumferentially notched tube specimens with stress triaxiality larger than 0.7 in order to asses the influence of the Lode parameter on ductility in the moderate stress triaxiality regime. The effective plastic strain, the stress triaxiality T and the Lode parameter L were determined at the center of the notch up to the point of onset of failure by means of finite element. The influence of the Lode parameter on the failure strain was significant for the high strength and low hardening material, whereas for the medium strength and high hardening material the influence of the Lode parameter was less distinguished. The experimental results were then analyzed with the micromechanical model proposed by Barsoum and Faleskog (2011) [15], which is based on the assumption that ductile failure is a consequence of that plastic deformation localizes into a band. The band consists of a square array of equally sized cells, with a spherical void located in the center of each cell, which allows for studying a single 3D unit cell with fully periodic boundary conditions. The unit cell is subjected to a proportional loading such that it resembles the stress state, in terms of T and L, from the experiments. The micromechanical model captures the experimental trend and the influence of L on ductility very well. It is found that the Lode parameter sensitivity increases by the combination of increase in the yield strength and decrease in strain hardening. The fractographical analysis reveals that this Lode parameter sensitivity is associated with the failure characteristics of the material. [Copyright &y& Elsevier]

Abstract: A micromechanical model consisting of a band with a square array of equally sized cells, with a spherical void located in each cell, is developed. The band is allowed a certain inclination and the periodic arrangement of the cells allow the study of a single unit cell for which fully periodic boundary conditions are applied. The model is based on the theoretical framework of plastic localization and is in essence the micromechanical model by Barsoum and Faleskog (Barsoum, I., Faleskog, J., 2007. Rupture mechanisms in combined tension and shear—micromechanics. International Journal of Solids and Structures 44(17), 5481–5498) with the extension accounting for the band orientation. The effect of band inclination is significant on the strain to localization and cannot be disregarded. The macroscopic stress state is characterized by the stress triaxiality and the Lode parameter. The model is used to investigate the influence of the stress state on void growth and coalescence. It is found that the Lode parameter exerts a strong influence on the void shape evolution and void growth rate as well as the localized deformation behavior. At high stress triaxiality level the influence of the Lode parameter is not as marked and the overall ductility is set by the stress triaxiality. For a dominating shear stress state localization into a band cannot be regarded as a void coalescence criterion predicting material failure. A coalescence criterion operative at dominating shear stress state is needed. [Copyright &y& Elsevier]

Abstract: A micromechanics model based on the theoretical framework of plastic localization into a band introduced by Rice is developed. The model consists of a planar band with a square array of equally sized cells, with a spherical void located in the centre of each cell. The periodic arrangement of the cells allows the study of a single unit cell for which fully periodic boundary conditions are applied. The micromechanics model is applied to analyze failure by ductile rupture in experiments on double notched tube specimens subjected to combined tension and torsion carried out by the present authors. The stress state is characterized in terms of the stress triaxiality and the Lode parameter. Two rupture mechanisms can be identified, void coalescence by internal necking at high triaxiality and void coalescence by internal shearing at low triaxiality. For the internal necking mechanism, failure is assumed to occur when the deformation localizes into a planar band and is closely associated with extensive void growth until impingement of voids. For the internal shearing mechanism, a simple criterion based on the attainment of a critical value of shear deformation is utilized. The two failure criteria capture the transition between the two rupture mechanisms successfully and are in good agreement with the experimental result. [Copyright &y& Elsevier]

Abstract: An experimental investigation of the rupture mechanisms in a mid-strength and a high-strength steel were conducted employing a novel test configuration. The specimen used was a double notched tube specimen loaded in combined tension and torsion at a fixed ratio. The effective plastic strain, the stress triaxiality and the Lode parameter were determined in the centre of the notch at failure. Scanning electron microscopy of the fractured surfaces revealed two distinctively different ductile rupture mechanisms depending on the stress state. At high stress triaxiality the fractured surfaces were covered with large and deep dimples, suggesting that growth and internal necking of voids being the governing rupture mechanism. At low triaxiality it was found that the fractured surfaces were covered with elongated small shear dimples, suggesting internal void shearing being the governing rupture mechanism. In the fractured surfaces of the high-strength steel, regions with quasi-cleavage were also observed. The transition from the internal necking mechanism to the internal shearing mechanism was accompanied by a significant drop in ductility. [Copyright &y& Elsevier]

This article presents a nonlocal gradient-enhanced damage model that uses direction-dependent damage evolution and interfacial damage to predict transgranular and intergranular cracks in polycrystalline materials at the microstructural level. The distinct grains within the polycrystalline morphology are modeled as anisotropic linear elastic domains with random spatial orientation and cubic symmetries. Transgranular micro-cracks are assumed to occur along specific preferential cleavage planes within each randomly oriented crystal and are described using a bulk damage variable. For intergranular fracture, a smeared description of interface decohesion is incorporated through an interface damage variable which depends on the modified interface kinematics based on a cohesive law that uses a smoothed displacement jump approximation. The coupled system of equations in the proposed computational framework is decoupled using an operator-split methodology to ensure a robust and straightforward computational implementation. Several numerical examples are presented, and simulations are performed on single crystal, bicrystals, and polycrystalline domains to demonstrate the capabilities and validation of the proposed model. [ABSTRACT FROM AUTHOR]

[Display omitted] • A methodology is proposed to design novel isosurface strut lattice structure (ISLS) derived from TPMS. • Structural element of ISLS were modeled using beam and solid tetrahedron elements. • Stiffness, Anisotropy index, and fatigue properties were determined. • Anisotropy analysis showed that ISLS exhibit near isotropic behavior for all relative densities. • Low elastic modulus and superior fatigue resistance demonstrate suitability of ISLS as biomaterial scaffolds. This paper proposes a novel methodology to design a family of strut-based lattice structures derived from isosurfaces. Here the methodology is applied on isosurfaces obtained from Triply Periodic Minimal Surfaces (TPMSs). A Schoen's Gyroid TPMS morphology was employed to generate an isosurface strut lattice structure (ISLS). The structural element of ISLSs were modeled as solid tetrahedral and beam elements. Finite element simulations were performed to compute the effective mechanical properties such as stiffness, anisotropy index and fatigue properties for range of relative densities, i.e., 5% to 35%. An isosurface strut mesh sensitivity study was performed to determine number of mesh points required for consistency in mechanical properties. Stretch dominated sheet Gyroids are found to be most superior lattices for mechanical properties in literature and hence the truss based ISLS is compared to sheet Gyroids. The scaling laws demonstrated that Gyroid ISLS modelled with both beam elements and solid elements exhibited bending dominated behavior and yet ISLS solid elements show an elastic modulus, bulk modulus, and shear modulus, comparable to stretch-dominated sheet Gyroids. Anisotropy analysis showed that ISLS exhibit near isotropic behavior for all relative densities. Results exhibited that for the same relative density, ISLS modelled with beam elements showed lower elastic modulus, but higher fatigue performance as compared to the solid elements. Highly porous, low elastic modulus and superior fatigue resistance demonstrate suitability of ISLS beam as biomaterial scaffolds whereas ISLS solid having high modulus are useful in applications requiring enhanced mechanical strength. [ABSTRACT FROM AUTHOR]

• The influence of the S, P, and Si and the δ-ferrite content on the susceptibility of AISI 310S to weld solidification cracking is investigated. • Adequate control of S and P to less than 0.02%, and Si away from 1.5 to 2.5% was found key in preventing solidification cracking. • Benchmarking the case results with the modified Suutala and Pacary curves revealed close outcomes. Solidification cracking is very common in the welding process of austenitic stainless steels and can lead to premature failures. Yet, the main quantitative impact of S, P and Si on solidification cracking is still lacking. In addition, the present solidification cracking prediction diagrams are merely composition based, i.e., C r e q / N i e q dependent. Hence, this work aim to highlight the importance of controlling S, P, Si, and δ-ferrite on the susceptibility of AISI 310S to solidification cracking. Penetrant testing, XRF spectrometry, hardness, ferrite measurements, along with microscopic examination were used. XRF spectroscopy revealed 0.09% S, 0.09% P and 2.27% Si at the weld which are deemed to be in critical range according to the reported literature and ASTM A240. Benchmarking the results with the modified Suutala and Pacary curves revealed close results. Therefore, outcomes from this work can aid in the development of such prediction diagrams, along with improvement to the refining industry. [ABSTRACT FROM AUTHOR]

[Display omitted] • Quaternary ammonium copolymers having different hydrophilicity/hydrophobicity are tested as casing and tubing corrosion inhibitors. • Polymeric surfactants with higher hydrophobicity showed better protection potential than surfactants with higher hydrophilicity. • They become effective by adsorbing on the metal surface using their hydrophilic segments, and their adsorption follows Langmuir isotherm. • Polymeric surfactants retards both anodic and cathodic reactions and mainly behave as cathodic-type inhibitors. • DFT study suggests that quaternary nitrogens deprotonate and coordinate with the metallic surface using their unshared electron pairs. In this study, two quaternary ammonium-based copolymers (DAC-DAD10 and DAC-DAD20) with varying hydrophilicity/hydrophobicity are synthesized, characterized, and their capacity to suppress P110 carbon steel (P110 CS) corrosion in 3.5% NaCl is examined. DAC-DAD10 and DAC-DAD20 were synthesized using diallylammonium chloride (DAC) and N1, N1-diallyl-N6-dodecyl-N6, N6-dimethylhexane-1,6-diaminium dichloride (DAD) and their inhibition potential (%IE) and mechanism were studied by different experimental and computational methods. The outcomes suggest that the %IE of DAC-DAD10 and DAC-DAD20 increases on increasing the hydrophobicity as DAC-DAD20, having a large hydrophobic alky chain, showed relatively better %IE than DAC-DAD10. DAC-DAD10 and DAC-DAD20 manifest the best %IE of 88.68% and 96.17%, respectively, at concentrations as low as 3 mgL-1. Potentiodynamic polarization studies indicate that they behave as cathodic-type inhibitors. Their adsorption on the metallic surface followed the Langmuir adsorption isotherm. Various surface analyses, including SEM-EDS, and XPS, confirm that they adsorb at the metal and electrolyte interface and build a corrosion protective layer. DFT study suggests that quaternary nitrogen atoms easily deprotonate and coordinate with the metallic surface using their unshared electron pairs. The corrosion inhibition based on experimental and computational analyses is schematically presented and described. [ABSTRACT FROM AUTHOR]

[Display omitted] • Porous bone plates with cubic (C), diamond (BCC) and body-centered cubic (CBCC) structures were prepared. • Axial compression, torsional and bending tests were carried out to check the designs' reliability. • CBCC structure with enhanced performance was used with varying rows' and porosities. • Finite element analysis was used to check the biomechanical performance of bone plates. • Increased porosity enhanced the callus volume but displayed poor mechanical performance. The current study investigates the biomechanical performance of porous bone plates augmented with three different cellular lattice structures, e.g., body-centered cube (BCC), simple cube (SC), and the superposition of simple and body-centered cube (SC-BCC) structures. The SC-BCC cellular structures, exhibiting improved torsional, compression, and bending stiffness, were strategically integrated into the bone plates. Configurations ranging from one to three rows, with porosity ranging from 30% to 90%. Increasing the number of rows and porosity maximized the interfragmentary movement at the fracture site. Specifically, SC-BCC configurations with one, two and three rows at 90% porosity demonstrated callus volume improvements of 31.33%, 42%, and 43.2%, respectively, compared with the lowest callus volume observed with SC-BCC at one row and 30% porosity. Regardless of the improved volume, callus stiffness was highest at 30% and 90% porosity levels across all cases, indicating more mature tissue formation in calluses and better physiological load support. High stresses located at 90% porosity, followed by 50% porosity, discouraged their mechanical performance. Therefore, employing 30% porosity configurations with appropriate vertical rows for desired movement is recommended for optimal biomechanical performance. However, 90% porosity may be suitable in scenarios involving minimal forces and restricted patient movement. [ABSTRACT FROM AUTHOR]

• Assessing welding distortions in a large structure experimentally and numerically. • Demonstrating the quality in numerical results using simplified CWM techniques. • Identifying the parameters having significant impacts on the welding distortions. Unwanted distortions are typically observed in components after the welding process. Physical trial tests and extra post-treatments are being widely utilized in industries to minimize and correct the out of tolerance distortions. These methods are time-consuming and costly. There has been growing interest in digital tools which have great potential to minimize the physical test loops and corrections. In this study welding distortions analysis has been carried out on a large beam structure experimentally and numerically using computational welding mechanics (CWM) techniques such as the inherent strain (local–global) method and the shrinkage method, together with the lumping approach. The estimated distortions from the shrinkage together with lumping approaches were in good agreement with the experimental measurements and the computational time affordable. The inherent strain (local–global) method captured the trend of distortion with an underestimation of distortions. The accuracy of the estimated residuals stresses from the inherent strain (local–global) approach is higher than the one from shrinkage together with lumping approaches. Moreover, the effects of various welding process parameters (i.e. welding sequence, fixture, and weld pool size) on welding distortions were investigated. It is found that following the proper welding sequence could minimize the welding distortion of the beam structure. Increasing the constraints of fixtures can prevent welding distortion effectively and reducing weld pool size results in less welding distortions of the beam structure. [ABSTRACT FROM AUTHOR]

Several carbon steel tubing suffered severe corrosion in service which resulted in the leakage of production fluids from tubing string and, consequently, a decrease of well productivity. Optical metallographic microscopy, X-ray diffraction (XRD), combined with weight loss and characterization methods were used to determine the most probable causes of the failure. The results showed that the composition and structure of the tubing joints and couplings were in accordance with the parameter requirements of API 5CT for grade J55. Upon visual inspection, the corroded pipe exhibited significant thickness reduction in multiple locations, which justifies utilizing the triaxial yield of pipe body formula, assuming the minimum measured thickness as the nominal thickness of the pipe. When compared to the upper bound internal pressure requirements in API 5CT, the equivalent stress calculation showed significantly lower failure pressure levels, which provide strong evidence that the pipe could not withstand actual service conditions. The composition of corrosion products was mainly FeCO 3 and Fe 3 O 4 , and scaling layer were composed of the heavy components of the crude oil, CaCO 3 and corrosion products. The scaling layer was protecting the steel surface from corrosion and reducing the corrosion rate. Once the scaling layer was broken, the corrosion rates increased. Also, pitting corrosion rates simulations were conducted at locations with the highest corrosion risk. Results show that at the first 30 days, pitting corrosion rates are the highest at these locations due to many factors including high CO 2 partial pressures, acidic pH at these locations, and larger production volumes resulting in an increase of wall shear stresses and higher velocities. • Microscopy and X-ray spectroscopy used to investigate carbon steel tubing failure. • Pipe unable to withstand service conditions evident by stress calculations. • The composition of corrosion products was mainly FeCO 3 and Fe 3 O 4. • Pitting corrosion rates first 30 days due to high CO 2 partial pressures, acidic pH, and larger production volumes. [ABSTRACT FROM AUTHOR]

In this study the fatigue strength of fillet welded tube-to-plate joints failing at the weld root and subjected to multi-axial stress states is investigated. The fatigue test data is collected from the literature and it is assessed together with the experimental data generated in this study. Finite element analysis is used to analyze the stress state at the weld root. The fatigue strength estimation capabilities of local stress based methods such as the Principal Stress Hypothesis (PSH), von Mises Stress Hypothesis (vMH), Modified Wöhler Curve Method (MWCM), and Effective Equivalent Stress Hypothesis (EESH) are compared. The applicability of modified Gough Pollard Equation (GPE) in local stress system is also assessed. It is observed that most of the proposed local stress assessment methods can estimate the fatigue strength of fillet welds subjected to multiaxial stress states with constant principal stress direction, e.g. proportional loading. In case of load histories which produce varying principal stress directions with respect to time, e.g. non-proportional loading, better estimation capability is shown by MWCM and EESH. In most of the cases of varying principal stress direction load histories, vMH and PSH fail to estimate the fatigue strength. The fatigue strength of specimens tested with combined loading is reduced in comparison to the fatigue strength of specimens tested with only internal pressure and only bending loading. Out-of-phase loading does not affect the fatigue strength significantly for the specimens in this study. However; a decrease in fatigue strength is observed for the test data for out-of-phase loading collected from the literature. [ABSTRACT FROM AUTHOR]

High density polyethylene (HDPE) can show viscoelastic-viscoplastic behaviors under monotonic loads and a stress softening after reloading under cyclic ones. This sets a challenge in simultaneously representing such response in material constitutive models. In addition, due to the adoption of novel accelerated tests at higher temperatures, e.g., 95 °C, the need for a higher temperature calibration is motivated. Therefore, the objective of this study is threefold: (i) to investigate the capability of the three network viscoplastic (TNV) model in capturing HDPE thermo-viscoplasticity under monotonic and cyclic loads, (ii) to report observations on HDPE at various strain-rates and temperatures from 23 °C to 95 °C including the α-relaxation region (iii) to explore the ratcheting behavior of HDPE, i.e., cyclic creep. The FEA analysis based on the calibrated TNV model was successfully able to predict the HDPE behavior under static, quasi-static and dynamic loads. The predicted strain range Δ ε and mid-range strain ε s of the cyclic creep showed good agreements. This implies that the TNV model can be a reliable candidate for HDPE engineering assessments. Findings of this work will have many industrial applications, e.g., products manufacturers or resin producers, in which HDPE is used under complex loads. Similar procedures can be followed for other thermoplastics which lays the basis for establishing a standard calibration guideline. • The thermal viscoelastic viscoplastic behavior of HDPE under monotonic and cyclic loading conditions are investigated. • A constitutive model was calibrated and validated under static, quasi-static and dynamic cyclic loads. • Observations on HDPE with various strain-rates and temperatures from 23 °C to 95 °C are reported. • The calibrated FEA model was successfully able to capture the cyclic creep behavior of HDPE, up to 500 cycles. [ABSTRACT FROM AUTHOR]

The present study investigates the influence of thermo-mechanical material properties of different steel grades (S355–S960) on welding residual stresses and angular distortion in T-fillet joints. Different cases in which temperature dependent thermo-mechanical material properties are considered as constant, linear, and as a function of temperature are simulated by using finite element (FE) method. Experiments are carried out to evaluate temperature dependent yield stress and Young’s modulus for S700 and S960 steel grades. Furthermore, JMat Pro software is used to obtain the remaining thermo-mechanical material properties. The numerical predictions of angular distortion and transverse residual stresses are validated with experimental measurements. It is observed that for assessment of residual stresses, except yield stress, all of the thermo-mechanical properties can be considered as constant. For the prediction of angular distortions with acceptable accuracy, heat capacity, yield stress and thermal expansion should be employed as temperature dependent in the welding simulations. [ABSTRACT FROM AUTHOR]