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The automotive industry is undergoing significant changes driven by factors such as reducing carbon dioxide emissions, advancing technology, evolving regulations, and the emergence of new energy sources. Lightweight materials, particularly aluminum alloys, are being extensively researched and integrated into vehicles to reduce weight and improve performance. However, the heating process during vehicle production can cause thermal buckling in thin aluminum alloy structures, affecting their appearance and quality. While thermal buckling has been studied in other industries, research in the automotive sector, particularly for non-structural parts like car roofs, is limited. This study uses numerical simulation to predict thermal buckling and post-buckling behavior of a EN AW 6016-T4 alloy car roof assembled in a predominantly steel body-in-white. The research findings indicate that roof buckling occurs at a relatively low temperature difference of approximately 60 °C, which is lower than the maximum temperatures experienced during the painting phases in the automotive industry. Consequently, undulations in the roof's shape become apparent, underscoring the importance of design modifications to ensure visual conformity. Validation through physical testing confirms the model's accuracy, providing valuable insights for designing lightweight structures with improved performance and aesthetics.

Abstract: More and more accurate models have been developed for describing the mechanical behavior of an adhesive in an assembly which allow to numerically optimize the design of bonded assemblies. This paper deals with stress analysis in coaxial bonded joints. The objective was to analyze the effect of various geometries of the different parts of the assembly in order to optimize the maximal transmitted load of such joints. In the case of tensile loads, the stress distributions were analyzed using axisymmetric theory of elasticity. A pressure-dependent elastic limit of the adhesive was used, in order to accurately represent the difference between tensile-shear and compression-shear loads in the mechanical response of the adhesive. In adhesively bonded joints, stress concentrations can contribute to the initiation and propagation of cracks in the adhesive. Therefore, designing adhesively bonded assemblies which strongly limit stress concentrations can significantly increase the load transmitted by the assembly. Moreover, cylindrical joints are associated with high substrate strength in the radial direction, meaning that peel and cleavage forces have different effects compared to single lap joints. A comparison between the mechanical behavior of these two joints is proposed, starting from 2D simulations in the case of tensile and compressive loads. Furthermore, the influence of the angle of conical geometries of the bonded area, which can easily be used for such assemblies, is analyzed with respect to the stress distributions. It is shown that several geometries allow a large reduction of stress concentrations and thus lead to stronger assemblies. Moreover the influences of several geometries which strongly limit stress concentrations are presented. [Copyright &y& Elsevier]

Abstract: This study is concerned with increasing the performance of adhesively bonded structures. Adhesively bonded joints offer many advantages, but stress singularities can contribute to the initiation and the propagation of crack in adhesive joints. Therefore, designing adhesively bonded joints which strongly limit the influence of edge effects can significantly increases the transmitted load by the assembly. Cylindrical joints are associated with high substrate strength in the radial direction, meaning that peel and cleavage forces have different effects compared to simple lap joints. But, for such assemblies, edge effects also exist. The aim of this paper is first to analyse stress concentrations in cylindrical joints in the case of axial loadings, starting from refined finite element computations under a linear elastic assumption. Thus as the stress state in the adhesive thickness can be complex associated to edge effects, simplified methods can lead to an overestimation of the transmitted load by the assembly as they generally are not able to represent effects of stress concentrations in the adhesive thickness. Secondly, geometries which strongly limit the influence of edge effects are proposed. An optimisation of the maximum transmitted load of cylindrical joints is proposed using a pressure-dependent elastic limit of the adhesive. [ABSTRACT FROM AUTHOR]

A letter to the editor is presented in response to the article "Simple aspiration and drainage and intrapleural minocycline pleurodesis versus simple aspiration and drainage for the initial treatment of primary spontaneous pneumothorax: An open-label, parallel-group, prospective, randomised, controlled trial," by Jin-Shing Chen and colleagues in the April 13, 2013 issue.

Context.—: During the coronavirus disease 2019 pandemic, several studies have described a distinctive cutaneous manifestation with a clinical picture resembling chilblains or chilblain lupus in young patients., Objective.—: To report the histopathologic description of a series of chilblainlike lesions appearing in the context of the severe acute respiratory syndrome coronavirus 2 epidemic., Design.—: The study included 13 patients with cutaneous acral lesions resembling chilblains occurring in the setting of suspected severe acute respiratory syndrome coronavirus 2 infection with available skin biopsy., Results.—: Two main histopathologic patterns were observed: a chilblainlike histopathologic pattern (10 of 13 cases; 77%) and a thrombotic vasculopathy pattern (3 of 13 cases; 23%). The chilblainlike histopathologic pattern featured a superficial and deep perivascular infiltrate of lymphocytes of varying intensity. This infiltrate was sometimes peri-eccrine and alterations of eccrine glands were present in most cases. Vacuolar alteration of the basal layer of the epidermis was found in a majority of patients. Lichenoid interface dermatitis was rarely present. The thrombotic vasculopathy pattern featured an absent or mild inflammatory infiltrate, multiple intraluminal fibrin thrombi, and ischemic epidermal necrosis. In both patterns, no true vasculitis was observed. No patient tested positive for severe acute respiratory syndrome coronavirus 2 by polymerase chain reaction, possibly because these lesions may represent late cutaneous manifestations of the disease or are associated with an early effective immune response., Conclusions.—: The relationship of chilblainlike lesions to severe acute respiratory syndrome coronavirus 2 requires further investigations. Histopathologic features mimic chilblains, chilblain lupus, and, less frequently, a thrombotic vasculopathy. Response to viral infection might trigger diverse mechanisms leading to the 2 histopathologic patterns described.