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This paper investigates the environmental impact and mechanical performance of two composite sandwich structures, named Series 1 and Series 2, used in high-performance racing boats. Mechanical tests, including four-point bending and drop impact tests, were performed. It was found on a general basis that Series 2 has higher load-bearing capacity and limited deflection. Series 1, which has a higher density, was able to absorb more impact energy but was more susceptible to damage. A Life Cycle Assessment (LCA) was conducted to evaluate the environmental impact associated with the materials, considering also the testing phase, which plays an important role in the life cycle of materials and structures for advanced marine applications. In addition, two performance indexes were introduced to correlate the mechanical and environmental properties of the analyzed materials. This study emphasizes the importance of considering the testing phase in LCA, as the energy-intensive nature of mechanical testing contributes significantly to the overall environmental impact. The introduced indexes allow for a more comprehensive understanding of the balance between mechanical performance and environmental sustainability. The findings suggest a trade-off between mechanical performance and sustainability, calling for further research into recyclable composites and greener manufacturing processes to balance these competing priorities.

Fatigue damage represents a key failure mode in ship structures. Such damage typically begins at vulnerable points in the structure, like welded joints, stress concentration areas, and cracks. Cyclic loading, particularly from waves, encountered by ships during their operational life is a major cause of fatigue damage, which is the main focus of this study. There are various methods to address different sea state conditions, though they can sometimes be approximate. This paper aims to review the most commonly used methods to highlight their strengths and weaknesses and to provide essential background knowledge for developing reliable theoretical and numerical models for predicting the fatigue life of ship structures exposed to various sea states over their lifetime. The primary theoretical approaches discussed include energy spectral methods in both time and frequency domains, which are used to quantify wave-related energy and amplitude characteristics and evaluate wave loads for predicting the fatigue life of structures and welded joints. The discussion also covers the determination of cyclic stress in specific structural details of the hull girder and welded joints to identify the relevant maximum stress range for subsequent fatigue studies conducted using finite element analysis.

The main objectives of the present study were the application and validation of the newly proposed Digital Image Correlation equivalent structural strain approach for assessing the low-cycle fatigue life of S235 welded joints. Low-cycle fatigue tests were performed at a displacement ratio of minus one. Experimental tests were performed using two different ways of controlling the displacement amplitude: applying traditional low-cycle fatigue tests at a constant amplitude and stepwise succession tests at increasing amplitudes. A comprehensive, independent experimental procedure, proposed by the authors and not yet validated for steel welded joints, was applied to assess the equivalent structural strain range using the Digital Image Correlation technique for the traditional low-cycle fatigue tests and stepwise succession tests at increasing amplitudes. It is noteworthy that the values of the DIC equivalent structural strain (ΔEs from the DIC), calculated on the external sides of the samples, were utilized to predict fatigue life in correlation with the ASME mean curve and fall within the ±3σ scatter bands (external bands). In particular, most of the tests lie within the ±2σ boundary of the design curves except for some tests at low applied displacements. Moreover, it was shown that this method is applicable to stepwise succession tests with increasing displacement amplitudes, leading to significant time savings compared to conventional experimental tests.

A systematic and narrative literature review was performed, focusing attention on the anatomy of the area located at the junction of the sphenoid and the basal portion of the temporal bone (petrous bone, petrous apex, upper petro-clival region) encircled by the free edge of the tentorium, the insertion of the tentorium itself to the petrous apex and the anterior and posterior clinoid processes that give rise to three distinct dural folds or ligaments: the anterior petroclinoid ligament, the posterior petroclinoid ligament and the interclinoid ligament. These dural folds constitute the posterior portion of the roof of the cavernous sinus denominated “the oculomotor triangle”. The main purpose of this review study was to describe this anatomical region, particularly in the light of the relationships between the anterior margin of the free edge of the tentorium and the above-mentioned components of the sphenoid and petrous bone.

Background: Anterior cervical discectomy and fusion (ACDF) still represent the mainstream surgical approach in the treatment of degenerative cervical Degenerative Disc Disease (DDD), being a loss of mobility at the treated segment and adjacent segment diseases well-known complications. To overcome those complications, hybrid surgery (HS) incorporating ACDF and cervical disk arthroplasty is increasingly performed for DDD. Methods: We retrospectively reviewed the clinical, surgical, and outcome data of 62 consecutive patients (male/female, 29/37) harboring cervical disk herniation with or without osteophytes, with radiculopathy with or without myelopathy, who underwent a cervical discectomy on two or more levels with the anterior approach with at least one disk prosthesis along with cage and plate or O Profile screwed plate. Results: All the patients improved regardless of the cervical construct used. No significant relationship between different kind of prostheses as well as their surgical level, the number and the site of the cages (screwed and/or plated) was found out concerning immediate stability, dynamic prosthesis effectiveness, and clinical improvement in all the patients up to the maximum follow-up. Conclusions: Although the optimal surgical technique for cervical DDD remains controversial, HS represents a safe and effective procedure in selected patients with multilevel cervical DDD, as demonstrated by biomechanical and clinical studies and the present series. Some technical aspects should be considered when dealing with this procedure, like the drilling of the endplate, and some radiological findings have to be detected because potentially predictive of future misplacement.

Background: The introduction of recent innovations in the field of intraoperative imaging and neuronavigation, such as OArm Stealth Station, allows to obtain crucial intraoperative data by performing safer and controlled surgical procedures. As part of the improvement of surgical visual magnification and wide expansion of surgical corridors, the 3D-4K exoscope (EX) represents nowadays an interesting and useful tool. Transoral approach (TOA) represents the historical gold standard direct microsurgical route to ventral craniovertebral junction (CVJ). Methods: We herein report a preliminary experience on 6 cases of 33 patients operated by TOA concerning the simultaneous application of OArm with Stealth Navigation system (Medtronic, Memphis, TN) and imaging system along with the 3D-4K EXs in TOA for the treatment of CVJ pathologies. Results: Neither intraoperative neurophysiological changes nor postoperative infections occurred, but a neurological improvement was evident in all the patients. A complete decompression along with stable instrumentation and fusion of the CVJ was accomplished in all cases at the maximum follow-up (mean: 16.8 months). Conclusions: With EX, the role of surgeon become self-sufficient with a better individual surgical freedom compared to endoscopic surgery and excellent 3D vision and magnification. OArm allows an absolutely reliable intraoperative support for a more effective CVJ decompression. Nevertheless, with OArm-assisted neuronavigation, it can be difficult to navigate C1 lateral masses and C2 isthmi, and to convert 3D into 2D real-time navigation, it can become quite complicate. Finally, the association of EX and OArm appears more time consuming compared to the old fashion one.

The ship hull structure is composed of plates and stiffened panels. Estimating the maximum load-carrying capacity, or the ultimate strength, of these structural components is fundamental. One of the main challenges nowadays is the implementation of new materials and technologies to enhance the structural integrity, economy, safety and environmentally friendly design of the ship’s hull structure. A new design solution may be represented by aluminium alloy honeycomb sandwich structures, both as plane panels or stiffened ones, which are characterised by excellent impact-absorption capabilities and a high stiffness-to-weight ratio. Still, their response to some conditions typical of ship structural design needs to be deeply investigated. Axial compressive loading is one of the most critical conditions that could impact the structural integrity of such light-weight solutions. Hence, the uniaxial compressive behaviour of aluminium honeycomb sandwich structures has to be deeply investigated to promote their integration in ship structural design. Within this context, the present work performs an experimental and numerical study of a honeycomb sandwich panel subjected to uniaxial compressive loads. The results will help develop models for predicting the uniaxial compressive load-carrying capacity of hybrid honeycomb sandwiches of aluminium alloy design.

This study aims to propose a thorough experimental methodology to assess the mechanical quality of dissimilar joints. This comprehensive approach investigates the fatigue behavior by exploiting the thermographic method, accompanying and correlating the results with information obtained from extensive measurements of residual stresses and detailed evaluation of fracture surfaces. The integration of the information obtained by this hybrid approach allows for a deeper understanding in terms of fatigue behavior even in complicated situations as those represented by dissimilar welded joints. A complex laser-welded Ti6Al4V/Inconel 625 dissimilar joint, obtained using intermediate inserts of Vanadium and AISI 304, was considered as case study. The residual stresses, both longitudinal and transverse to the weld beads, were measured on surface by means of X-ray diffraction, whereas, for in-depth measurements, the multiple-cut contour method was implemented to determine full 2D maps of longitudinal residual stresses with the first cut, and transverse stresses in the Vanadium insert with the second cut. In the investigation of longitudinal residual stresses, the area mostly affected by harmful tensile residual stresses is the weld between the stainless steel and Vanadium, where the maximum value of about 560 MPa is reached; the analysis of transverse residual stresses highlighted a maximum value of 350 MPa at the core of the Vanadium insert. The fatigue behavior of the joints was investigated along with a detailed analysis of the fractured surfaces by scanning electron and confocal microscopes. The analysis of the fracture surfaces indicated that the failure modes are mainly related to the occurrence of defects on the crack path, especially at stress range higher than 200 MPa, for which a large number of pores cluster were detected. Nevertheless, the crack initiation is usually on the side of Vanadium. When the crack path deviates on the stainless-steel region, the fracture mode is brittle due to high residual stresses.

Surgical removal of tumors of the atrium is challenging due to their deep location, vascularization, and to their complex three-dimensional relationships with the highly functional white matter fibers of the region. To assess the feasibility and the effectiveness of the ipsilateral interhemispheric transprecuneus approach (IITA) for tumors involving the atrium and the posterior third of the temporal horn, a retrospective chart review of all patients who had undergone a surgical treatment for intraventricular tumors between January 2008 and January 2017 was performed, and the step-by-step approach is described. Ten patients affected by lesions of the atrium of the lateral ventricle underwent surgical treatment, seven of which were approached through the IITA. The mean age was 42.8 years (range 6–63 years). The symptoms presented included severe, drug-resistant headache (90%), lateral homonymous hemianopsia (50%), seizures (30%), and speech disturbances (30%). Histological examinations revealed seven patients with meningioma (70%), one with a metastasis (10%), one with a choroid plexus papilloma (10%) and one with a cavernoma (10%). In all cases, a gross total removal was obtained. All patients had a significant improvement in their headache. Two patients experienced a worsening of the pre-operative visual disturbances, while two patients had a significant improvement. No patients without pre-operative visual disturbances described a post-operative worsening of visual symptoms. The IITA represents a feasible approach for tumors of the atrium. The three-quarter prone position facilitates the enlargement of the interhemispheric fissure by increasing the working angle and facilitating the exposure of the lateral wall of the atrium.

Combination of lightweight and sustainable marine structures represents a crucial step to accomplish weight reduction and improve structural response. A key point when considering the reliability of innovative structural solutions, which should not be neglected, is represented by large-scale experimental investigations and not only by small-scale specimen analysis. The present research activity deals with the experimental assessment of a lightweight ship balcony overhang, which incorporates an aluminium honeycomb sandwich structure and Al/Fe structural transition joints obtained by means of the explosion welding technique. The ship balcony overhang was formerly designed with the aim of proposing the replacement of ordinary marine structures with green and lightweight options. Experimental investigations of a large-scale structure were performed to validate the design procedure and to evaluate the feasibility of the proposed solution. Large-scale bending tests of the ship balcony overhang were performed considering representative configurations of severe loading conditions. The experimental analysis allowed the evaluation of the structure’s strength, stiffness and failure modes. Comparisons with analogous structures reported in the literature were performed with the aim of assessing the benefits and drawbacks of the proposed lightweight structure. Fatigue tests were also performed in order to evaluate the hardening and the hysteresis loops. The collapse modes of the structure were investigated using X-ray radiography. The structural transition joints have experienced no cracks during the static and fatigue tests. The results clearly indicated that the proposed solution can be integrated in new and existing ships, even if made of steel, as the Al/Fe structural transition joints produced by explosion welding can be used to connect the ship structure to the Al honeycomb balcony. The systematic analysis of the experimental results gave valuable data to enhance the design methodology of such structures.

This scientific study aims to validate the applicability of a micromechanical model for predicting the static shear strength of hybrid interfaces that are pressure-reinforced and bonded with anaerobic adhesives. To identify the parameters for the micromechanical model, a systematic experimental test plan involving high-strength steel butt specimens bonded with anaerobic adhesive in a finite thickness was performed. The experimental investigation was based on torque tests, which provided the shear strength of two anaerobic adhesives subjected to different values of contact pressure, ranging from 0 up to 1000 MPa. Based on the intrinsic high-pressure properties of the finite-layer adhesives, the formerly developed micromechanical model of hybrid interfaces satisfactorily predicted the macroscopic strength of tightened-bonded joints taken from the literature.

Welded joints are widely used in many sectors and represent the main joining technique also in the marine industry. The welded joints are sites of high stress concentrations and are subject to severe conditions for the marine environment. The design of marine welded joints has to consider the effects from wave loads, ship motions and loading/unloading operations and corrosion effects. The aim of this scientific work is to discuss about the state of the art of the standards and the approaches for predicting the fatigue life of welded joints used for the marine industry. Several approaches are examined in order to provide an overview and highlight the advantages and limitations of each method. Furthermore, recent advances in welding of dissimilar metals and autonomous welding are considered.

The aim of this scientific work was to evaluate the compression instability effects during static and low-cycle fatigue loadings of AA 5083 welded joints, commonly used in marine structures. Low-cycle fatigue assessment in marine structures is of utmost importance since high levels of plastic deformation can arise in the proximity of high-stress concentration areas. Displacement ratios equal to minus one and zero were used to perform experimental low-cycle fatigue tests. The tests were monitored by means of the Digital Image Correlation technique in order to detect the strain patterns, with particular attention paid to stress concentration areas, indicating that a specimen tends to buckle during high compression loads, for tests with a displacement ratio of minus one. The tests at displacement ratios equal to −1 showed a lowering of the strain–life curve revealing a considerable effect on compression instability. A nonlinear finite element modelling procedure, depending only on hardness measurements, was developed. The hardness measurements were used in order to assess the distinct mechanical properties of the different zones that were included in the finite element model. The finite element model results were compared to the data achieved by means of the digital image correlation technique, demonstrating that hardness measurements can help predict the low-cycle fatigue behaviour of welded joints and consider compression instability phenomena.

The aim of this research activity was to study the fatigue behavior of laser welded joints of titanium alloy, in which the welding was performed using a laser source and in the absence of filler material, by means of unconventional full field techniques: Digital Image Correlation (DIC), and Infrared Thermography (IRT). The DIC technique allowed evaluating the strain gradients around the welded zone. The IRT technique allowed analyzing the thermal evolution of the welded surface during all the fatigue tests. The fatigue limit estimated using the Thermographic Method corresponds with good approximation to the value obtained from the experimental fatigue tests. The obtained results provided useful information for the development of methods and models to predict the fatigue behavior of welded T-joints in titanium alloy

The aim of the present investigation was to assess the behaviour of strip-planked parts by comparing wooden specimens glued using two different bio-based adhesives with wooden specimens glued using a conventional epoxy resin generally used in boatbuilding. Experimental tests in accordance with UNI EN standards were performed in order to evaluate mechanical properties such as tensile strength, shear strength, elastic modulus and shear modulus. In addition, compression shear tests were performed in order to assess the shear modulus of the adhesives. The obtained results demonstrate that the mechanical properties of the investigated bio-based adhesives are comparable to, and sometimes better than, the conventional epoxy resin. Moreover, the experimental results give useful information for the design of wooden boats when the strip-planking process is used. Furthermore, a new procedure to assess the shear modulus of elasticity and shear strength, using the application of compression loadings, was proposed. The results were compared to standard lap-joint tests and showed even lower dispersion. Consequently, the testing procedure proposed by the authors is valid to assess shear properties under compression loading, and it can be applied in most laboratories since it involves the use of common testing devices.

The aim of this research activity was to study the fatigue behavior of laser welded joints of titanium alloy, in which the welding was performed using a laser source and in the absence of filler material, by means of unconventional full field techniques: Digital Image Correlation (DIC), and Infrared Thermography (IRT). The DIC technique allowed evaluating the strain gradients around the welded zone. The IRT technique allowed analyzing the thermal evolution of the welded surface during all the fatigue tests. The fatigue limit estimated using the Thermographic Method corresponds with good approximation to the value obtained from the experimental fatigue tests. The obtained results provided useful information for the development of methods and models to predict the fatigue behavior of welded T-joints in titanium alloy.

The aim of this scientific work was to investigate the behaviour of cruciform welded joints under static loading using a full-field technique: Digital Image Correlation. The material curves, relative to different zones (base material, heat affected zone, weld), were obtained by hardness measurements, which were done by means of a fully automated hardness scanner with high resolution. This innovative technique, based on the UCI method, allowed to identify the different zones and to assess their different mechanical properties, which were considered in the finite element model. Finally the finite element model was validated experimentally, comparing the results with the measurements obtained using the Digital Image Correlation technique.

BACKGROUND Anatomical dissections play an irreplaceable role in the training of new generations of effective neurosurgeons, especially when addressing skull base lesions is required.The Authors describe an inter-laboratory dissection study aimed at improving the knowledge of a complex region of the skull base. The anterior and middle incisural spaces are of remarkable anatomical and surgical interest due to complex relationships between bony, dural, arachnoidal, and neurovascular structures. The primary purposes of this study are to describe the anatomy of this region with particular emphasis on the relationships between the anterior margin of the free edge of the tentorium and the sphenoid and petrous bone; to identify surgical implications in many different types of neurosurgical procedures dealing with this challenging complex anatomic area.METHODS Thirteen anatomical specimens, including five injected specimens, were dissected in this study. In the formalin-fixed specimens, vessels were injected with colored silicone.RESULTS The anatomical study focused on the description of the relationships between bony dural, arachnoid, and neurovascular structures. Surgical implications are described accordingly.CONCLUSIONS Detailed anatomical knowledge of this region finds concrete applications in neurosurgical practice since the anterior and middle incisural spaces are often surgically exposed in neoplastic and vascular diseases. The high-definition pictures reported in this study could represent useful support to understand the anatomy of this complex region.Finally, our study could provide guidance to neurosurgical centers in which resources are limited that are either planning to establish their own cadaver dissection laboratory or failed to do so because of the supposed high-costs., (© 2023. The Author(s), under exclusive license to Springer Nature Switzerland AG.)

Purpose The role of cadaver labs in preparing new generations of effective neurosurgeons is of paramount importance. The Authors describe a personal cadaver lab experience aimed at improving the knowledge of a difficult region of the central skull base. The anterior and middle incisural spaces are regions of remarkable anatomical, and surgical interest due to complex relationships between bony, dural, arachnoidal, and neurovascular structures. The primary purpose of this study is (1) to describe the anatomy of this region with particular emphasis on the relationships between the anterior margin of the free edge of the tentorium and the sphenoid and petrous bone; (2) to identify surgical implications in many different types of neurosurgical procedures dealing with this challenging complex anatomic area.Methods Eight fresh, non-formalin-fixed non-silicon-injected adult cadaver heads and five injected formalin-fixed adult cadaver heads were analyzed in this study.Results The anatomical study was focused on the description of the relationships between bony, dural, arachnoid, and neurovascular structures. Surgical implications are described accordingly.Conclusions Detailed anatomical knowledge of this region finds concrete applications in neurosurgical practice since the anterior and middle incisural spaces are often surgically exposed in neoplastic and vascular diseases., (© 2023. The Author(s), under exclusive license to Springer Nature Switzerland AG.)

Background: Anterior cervical discectomy and fusion (ACDF) still represents the first surgical option in the treatment of cervical degenerative disc disease (DDD) but is still burdened by several complications secondary to the loss of mobility at the treated segment and adjacent segment diseases (ASDs). To overcome those complications, hybrid surgery (HS) incorporating ACDF and cervical disc arthroplasty (CDA) is increasingly performed for DDD., Methods: We retrospectively reviewed the clinical, surgical, and outcome data of 85 consecutive patients (M/F, 41/44) harboring cervical disc herniation with or without osteophytes, with radiculopathy and with or without myelopathy, who underwent the anterior approach to a cervical discectomy on two or more levels with at least one disc prosthesis, along with a cage and plate or an O Profile screwed plate., Results: All the patients improved regardless of the cervical construct used. No significant relationship between different kinds of prosthesis and their surgical level; the number of cages; and the site of the cages (screwed and/or plated) was found concerning immediate stability, dynamic prosthesis effectiveness, and clinical improvement in all the patients up to the maximum follow-up time., Conclusions: Although the optimal surgical technique for cervical DDD remains controversial, HS represents a safe and effective procedure in select patients with multilevel cervical DDD, as demonstrated by biomechanical and clinical studies and the present series., (© 2023. The Author(s), under exclusive license to Springer Nature Switzerland AG.)

BACKGROUND Anatomical dissections play an irreplaceable role in the training of new generations of effective neurosurgeons, especially when addressing skull base lesions is required.The Authors describe an inter-laboratory dissection study aimed at improving the knowledge of a complex region of the skull base. The anterior and middle incisural spaces are of remarkable anatomical and surgical interest due to complex relationships between bony, dural, arachnoidal, and neurovascular structures. The primary purposes of this study are to describe the anatomy of this region with particular emphasis on the relationships between the anterior margin of the free edge of the tentorium and the sphenoid and petrous bone; to identify surgical implications in many different types of neurosurgical procedures dealing with this challenging, complex anatomic area.METHODS Thirteen anatomical specimens, including five injected specimens, were dissected in this study. In the formalin-fixed specimens, vessels were injected with colored silicone.RESULTS The anatomical study was focused on the description of the relationships between bony dural, arachnoid, and neurovascular structures. Surgical implications are described accordingly.CONCLUSIONS Detailed anatomical knowledge of this region finds concrete applications in neurosurgical practice since the anterior and middle incisural spaces are often surgically exposed in neoplastic and vascular diseases. The high-definition pictures reported in this study could represent useful support to understand the anatomy of this complex region.Finally, our study could provide guidance to neurosurgical centers in which resources are limited that are either planning to establish their own cadaver dissection laboratory or failed to do so because of the supposed high-costs., (© 2023. The Author(s), under exclusive license to Springer Nature Switzerland AG.)