Single-use vape batteries: investigating their potential as ignition sources in waste and recycling streams

This study investigates the potential link between the increasing prevalence of single-use vapes (SUVs) and the rising frequency of waste and recycling fires in the UK. Incorrectly discarded Li-ion cells from SUVs can suffer mechanical damage, potentially leading to thermal runaway (TR) depending on the cells’ state of charge (SOC). Industry-standard abuse tests (short-circuit and nail test) and novel impact and crush tests, simulating damage during waste management processes, were conducted on Li-ion cells from two market-leading SUVs. The novel tests created internal short circuits, generating higher temperatures than the short-circuit test required for product safety. The cells in used SUVs had an average SOC ≤ 50% and reached a maximum temperature of 131 °C, below the minimum ignition temperature of common waste materials. The high temperatures were short-lived and had limited heat transfer to adjacent materials. The study concludes that Li-ion cells in used SUVs at ≤50% SOC cannot generate sufficient heat and temperature to ignite common waste and recycling materials. These findings have implications for understanding the fire risk associated with discarded SUVs in waste management facilities.Batterie

Recent advances in mechanical analysis and design of dynamic power cables for floating offshore wind turbines

This review paper presents a comprehensive analysis of the mechanical design and analysis of dynamic power cables for marine renewable energy applications, focusing on research from the last two decades. The review covers key aspects such as mechanical properties, failure mechanisms, fatigue analysis, experimental studies, local cable analysis, and global load analysis. The study aims to provide a concise summary of the state-of-the-art, identifying recent advancements and research gaps in the field. The methodology involves a systematic review of relevant literature, including journal articles, conference papers, and industry reports. The findings are synthesised to provide insights into the current understanding of power cable design and analysis, as well as to highlight areas requiring further research and development. The review is intended to serve as a valuable resource for researchers, engineers, and stakeholders in the marine renewable energy sector, contributing to the development of more reliable and cost-effective dynamic power cable solutions.Ocean Engineerin

Probabilistic ultimate strength analysis of submarine pressure hulls

ABSTRACTThis paper examines the application of structural reliability analysis to submarine pressure hulls to clarify the merits of probabilistic approach in respect thereof. Ultimate strength prediction methods which take the inelastic behavior of ring-stiffened cylindrical shells and hemispherical shells into account are reviewed. The modeling uncertainties in terms of bias and coefficient of variation for failure prediction methods in current design guidelines are defined by evaluating the compiled experimental data. A simple ultimate strength formulation for ring-stiffened cylinders taking into account the interaction between local and global failure modes and an ultimate strength formula for hemispherical shells which have better accuracy and reliability than current design codes are taken as basis for reliability analysis. The effects of randomness of geometrical and material properties on failure are assessed by a prelim-nary study on reference models. By evaluation of sensitivity factors important variables are determined and compare-sons are made with conclusions of previous reliability studies

Ductile Fracture Behavior of Mild and High-Tensile Strength Shipbuilding Steels

A comparison is made of the ductility limits of one mild (normal) and two high-tensile strength shipbuilding steels with an emphasis on stress state and loading path dependency. To describe the ductile fracture behavior of the considered steels accurately, an alternative form of ductile fracture prediction model is presented and calibrated. The present fracture model combines the normalized Cockcroft–Latham and maximum shear stress criterion, and is dependent on both stress triaxiality and Lode angle parameter. The calibrations indicate that, depending on the hardening characteristics of the steels, ductile fracture behavior differs considerably with stress state. It is demonstrated that the adopted fracture model is able to predict the ductile fracture initiation in various test specimens with good accuracy and is flexible in addressing the observed differences in the ductile fracture behavior of the considered steel grades

Fracture Estimation in Ship Collision Analysis—Strain Rate and Thermal Softening Effects

This study examined the effects of the strain rate and thermal softening on large-scale ductile fracture in ship collisions using a rate-dependent combined localized necking and fracture model. A Johnson–Cook type-hardening model, consisting of strain hardening, rate-sensitivity, and thermal softening terms, was adopted together with an associated flow rule. The temperature was treated as an internal state variable and was calculated from the plastic strain energy using a strain-rate-dependent weighting function under fully isothermal and adiabatic conditions. At every time increment, the fracture locus was updated based on the temporal strain rate, whereas the necking locus was coupled with the hardening law, which was dependent on both the strain rate and temperature. The damage indicator framework was used to consider the non-proportional loading paths. The dynamic shell-element failure model was verified through plate-panel penetration tests and applied to a large-scale ship collision analysis involving a struck ship/ship-shaped offshore installation and a supply vessel. The effects of the loading rate and impact energy were assessed in terms of the global behavior of the structure and observed failure modes

Evaluation of Localized Necking Models for Fracture Prediction in Punch-Loaded Steel Panels

This study compared the experimental test results on punch-loaded unstiffened and stiffened panels with numerical predictions using different localized necking modeling approaches with shell elements. The analytical models that were derived by Bressan–Williams–Hill (BWH) were used in their original form and extended version, which considers non-proportional loading paths while using the forming-severity concept and bending-induced suppression of through-thickness necking. The results suggest that the mesh size sensitivity depends on the punch geometry. Moreover, the inclusion of bending effects and the use of the forming-severity concept in the BWH criterion yielded improved estimations of fracture initiation with shell elements

Revisiting MARSTRUCT benchmark study on side-shell collision with a combined localized necking and stress-state dependent ductile fracture model

The MARSTRUCT benchmark study on a small-scale double hull structure penetrated by a hemispherical punch was revisited by employing a combined localized necking and stress-state dependent ductile fracture model. By using the limited information provided to the participants of the benchmark study, the plasticity and fracture model parameters were identified. To model the material behavior beyond moderate plasticity, a combination of the Swift and Voce strain hardening laws was used. The damage indicator framework using the Hosford–Coulomb fracture model, combined with the Domain of Shell-to-Solid-Equivalence (DSSE) concept, was adopted to predict the initiation and propagation of ductile fracture. Using the adopted approach, the predicted instant and force levels corresponding to the fracture initiation in the upper and lower plates were found to be in good agreement with the test results. The deformation of the structural elements was also accurately captured. The benefits of adopting the damage indicator framework and distinguishing different failure modes were investigated

Dent damage identification in stiffened cylindrical structures using inverse finite element method

The offshore industry has been using stiffened thin-walled steel cylindrical structures for decades, particularly as the columns of floating offshore installations. The floating offshore installations may be subjected to severe marine environmental conditions. Accidents such as collisions may also occur. Structural Health Monitoring (SHM) is a viable tool to maintain safe operation of offshore installations. Inverse Finite Element Method (iFEM) is one of the most powerful methods for SHM process. Hence, this study focuses on the application of iFEM methodology to thin-walled cylindrical structures representing the columns of floating offshore installations. iFEM methodology is verified by comparing its displacement results against reference finite element method (FEM) solution. After this verification, four different damage cases with different size, location and number of damages are considered. By using a newly introduced damage parameter and von Mises strain distribution iFEM accurately identified the correct damage locations and sizes. Therefore, it is concluded that iFEM can be used for structural damage prediction in offshore structures with high accuracy even if the number of the strain sensors is limited