1,721,058 research outputs found
Shape optimization of high-energy absorbers
No full textIn this paper, a new approach to simulate and to optimize the performances of a crash-box, in terms of energy absorption or acceleration peak, is presented. As soon as the maximum size of the crash-box (longitudinal and transversal dimensions) has been fixed, the new approach allows optimizing the shape of the transversal section and the thickness of the structure. Thanks to the proposed procedure, engineers can easily identify the best crash-box depending on the particular working conditions. The new method has been tested with different cases study by considering different objective functions. The obtained results show the procedure works well and also demonstrate that the optimal number of edges of the transversal section and the optimal crash-box thickness strongly depend on its main dimensions and on the considered objective function
VirDe: A new virtual reality design approach
No full textVirtual reality (VR), even if it does not represent
any more a novel technology, is one of the most powerful
tool to help designers during the development of new pro-
jects. This is proved by very numerous research activities
related to this field. In this research, we have studied a new
way to approach the development of a product. We present
the ongoing development of a system, called VirDe, acronym
of virtual design, which can allow the designers to perform
the whole design process, from the modelling phase to the
finite element method (FEM) simulation analysis, in a vir-
tual reality environment. This newmethod allows remarkable
time andmoney saving in the overall product design process,
but the most important contribution of VirDe is that, as far as
we concerned, there is no known similar approach which has
been studying the simultaneous combination of CAD, FEM
and virtual environment (VE)
A New Approach for CAD Modelling of Customised Orthoses by Generative Design
No full textThe standard method of design and manufacturing customised orthoses is still very time-consuming due to their often very complex shape. Different authors have tried to solve this problem but, unfortunately, the proposed approaches cannot be easily used in clinical practice because they require substantial interaction among medical staff and engineers or technicians.
The aim of this work is to present the framework of a new design approach that could allow clinicians to easily model a customised orthosis, without a skilled technician develops the entire procedure.
In particular, an automatic process based on Generative Design has been implemented. The obtained results have demonstrated that the implemented algorithm is simple to use and could allow also not-skilled users to design customised orthoses
Study of the performances of a fluidynamic actuator
No full textAim of this paper is presented a new methodology to study how different geometric parameters affect the performance of a hydraulic actuator. Preliminarily, the real working conditions of a hydraulic machine have been simulated by means of a CFD module. After, to test the reliability of the simulations, the obtained numerical results have been compared with the experimental data of a real prototype. This comparison demonstrates a good level of agreement between numerical and experimental results. Different simulations have been setup by modifying the actuator geometry and evaluating the efficiency of every analysed configuration. The results of this study give useful guidelines for the choice of the best geometry depending on the working conditions of the actuator
Statistical Shape Modelling as a Tool for Medical Reverse Engineering
No full textManipulating patient data acquired by Computer tomography (CT), e.g., anatomical shape and geometry, as well as studying the biomedical devices used in patient care, is certainly of remarkable importance. Here, Medical Re- verse Engineering (MRE) and Rapid Prototyping (RP) play a key role in the 3D models reconstruction of patient anatomy, that can be exploit to make patient- specific, custom-made devices. The inherent variability of the human anatomy can be a problem, which is why the concept of custom-made devices is men- tioned. In this field, MRE exploits the computational tools provided by Statistical Shape Modelling (SSM) and Principal Component Analysis (PCA) to achieve computer modelling of 3D data from real models. The PCA is a statistical tool for reducing the number of variables in a population, while the SSM enables the development of an infinite digital population of a given anatomy. This paper aims to show the potential of SSM in the field of the MRE. The study will focus on the pathological lumbar spine. Here, SSM provides new pathological geometries of the lumbar spine, which can be extrapolated and used to produce customized biomedical devices for that given pathological deformation, as well as to perform Finite Element (FE) simulations. Therefore, utilising SSM can bring an addi- tional edge to MRE, due to the infinite population of CAD models of patient anatomy, which can be useful in the medical industry, as already pointed out. © The Author(s), under exclusive license to Springer Nature Switzerland AG 2024
A virtual Concept of City Car
No full textIn this paper a virtual concept of a city car is proposed with the aim of approaching rationally the use of private and public means of transport, by combining the advantages of the traditional systems and the new technologies. The concept suggests the Drive by Wire interface for all the commands on board; this is based on electric signals, direction and moving operated by joystick. The simpleness of driving and the small dimensions could allow the use of the car to the disabled person without any additional device
On the left ventricular remodeling of patients with stenotic aortic valve: A statistical shape analysis
Full text linkThe left ventricle (LV) constantly changes its shape and function as a response to patho-logical conditions, and this process is known as remodeling. In the presence of aortic stenosis (AS), the degenerative process is not limited to the aortic valve but also involves the remodeling of LV. Statistical shape analysis (SSA) offers a powerful tool for the visualization and quantification of the geometrical and functional patterns of any anatomic changes. In this paper, a SSA method was devel-oped to determine shape descriptors of the LV under different degrees of AS and thus to shed light on the mechanistic link between shape and function. A total of n = 86 patients underwent computed tomography (CT) for the evaluation of valvulopathy were segmented to obtain the LV surface and then were automatically aligned to a reference template by rigid registrations and transformations. Shape modes of the anatomical LV variation induced by the degree of AS were assessed by principal component analysis (PCA). The first shape mode represented nearly 50% of the total variance of LV shape in our patient population and was mainly associated to a spherical LV geometry. At Pearson’s analysis, the first shape mode was positively correlated to both the end-diastolic volume (p < 0.01, R = 0.814) and end-systolic volume (p < 0.01, and R = 0.922), suggesting LV impairment in patients with severe AS. A predictive model built with PCA-related shape modes achieved better perfor-mance in stratifying the occurrence of adverse events with respect to a baseline model using clinical demographic data as risk predictors. This study demonstrated the potential of SSA approaches to detect the association of complex 3D shape features with functional LV parameters
Influence of the screw positioning on the stability of locking plate for proximal tibial fractures: A numerical approach
Full text linkTibial fractures are common injuries in people. The proper treatment of these fractures is important in order to recover complete mobility. The aim of this work was to investigate if screw positioning in plates for proximal tibial fractures can affect the stability of the system, and if it can consequently influence the patient healing time. In fact, a more stable construct could allow the reduction of the non-weight-bearing period and consequently speed up the healing process. For that purpose, virtual models of fractured bone/plate assemblies were created, and numerical simulations were performed to evaluate the reaction forces and the maximum value of the contact pressure at the screw/bone interface. A Schatzker type I tibial fracture was considered, and four different screw configurations were investigated. The obtained results demonstrated that, for this specific case study, screw orientation affected the pressure distribution at the screw/bone interface. The proposed approach could be used effectively to investigate different fracture types in order to give orthopaedists useful guidelines for the treatment of proximal tibial fractures
On the Finite Element Modeling of the Lumbar Spine: A Schematic Review
Full text linkFinite element modelling of the lumbar spine is a challenging problem. Lower back pain is among the most common pathologies in the global populations, owing to which the patient may need to undergo surgery. The latter may differ in nature and complexity because of spinal disease and patient contraindications (i.e., aging). Today, the understanding of spinal column biomechanics may lead to better comprehension of the disease progression as well as to the development of innovative therapeutic strategies. Better insight into the spine’s biomechanics would certainly guarantee an evolution of current device-based treatments. In this setting, the computational approach appears to be a remarkable tool for simulating physiological and pathological spinal conditions, as well as for various aspects of surgery. Patient-specific computational simulations are constantly evolving, and require a number of validation and verification challenges to be overcome before they can achieve true and accurate results. The aim of the present schematic review is to provide an overview of the evolution and recent advances involved in computational finite element modelling (FEM) of spinal biomechanics and of the fundamental knowledge necessary to develop the best modeling approach in terms of trustworthiness and reliability
Validating Finite Element Model for Lumbar Spine with Experimental Data
No full textIn the Medical Reverse Engineering (MRE) field, the manipulation of computed tomography (CT) scans from patients is complex, especially regarding the development of 3D anatomical models of patients' anatomy. This complexity depends on the variability of human anatomy, thus involving several challenges in the fabrication of custom biomedical devices. Low back pain is a worldwide widespread disease, whose cause is still unknown today. Indeed, a comprehensive understanding of spinal biomechanics is the goal that needs to be achieved for the evolution of surgical therapies and the design of useful devices for pathologies. Hence, Finite Element (FE) modelling of the lumbar spine is an important tool, useful for understanding the spinal physiological and pathological conditions. However, the obstacle of complex geometries is of extreme relevance. The aim of this paper is to support the existing literature to provide new models that can be used in FE modelling of the spine. Therefore, a novel model of the lumbar spine L45 with simplified intervertebral disc geometry was created and then the following model was validated using experimental data obtained from the literature about the long-term loading. This validated model based on long-term experiments will be useful in simulating the behaviour of the intervertebral disc during loading and unloading activities that alternate between night and day
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