1,721,205 research outputs found
Finite Elements Analysis of the Hyperelastic Impeller Rotating in the Self-Priming Pump
Full text linkVolumetric self-priming pumps with deformable impeller blades are very common devices in the food industry, especially in the presence of viscous liquids that tend to foam or contain suspended solids, but also when working under vacuum with good suction capacity is needed. These pumps are characterized by a circular chamber with an eccentric, in which the impeller rotates: due to the continuous deformation of flexible blades, the liquid is moved up to the discharge. The exact evaluation, moment by moment, of the hyperelastic behaviour of the impeller represents a quite complex task, involving several miscellaneous phenomena. In this study a simplified quasistatic analysis by finite element discretization is proposed, able to evaluate with reasonable approximation the stress/strain state of the impeller blades during their rotation. Aspects such as material hyperelasticity, large displacements, large deformations, non-linearity in contacts, frictional and inertial forces were considered
Actuality and perspectives of the wood industry development in western balkan countries
Full text linkWood mass represents a significant potential for the countries of the Adriatic region. Considering its geographic distribution, significant differences can be noticed. Those differences are mainly manifested regarding its quality and quantity. The aim of this paper is to emphasize the importance of territorial distribution of the wood mass from the aspect of its use in the wood industry. The result of the research procedure is to point out certain parts of the Adriatic region, where the development of the wood industry can be promoted
Investigating the resistance of reinforced barriers to high velocity projectiles
No full textThe resistance of concrete barriers to high velocity projectile impact from firearms is a research topic that has been of interest for quite some time, with the first known study going back to the mid-18th century. Despite this long history, only a very limited number of the test results are available in the public domain due to their sensitive nature and strategic importance. This situation has made the development of precise models for predicting the effects of ballistic impact difficult, despite the recent availability of highly refined and powerful calculation tools. Many researchers are still convinced that a validated methodology does not currently exist for this type of problem due to the number of uncertainties. Within this context, the objective of the present work is to study projectile impact on barriers made of reinforced concrete with explicit Finite Element (FE) simulations. In particular, this paper presents a FE analysis that considers the full range of projectile class as defined in the ballistic standards. Results from simulation are also compared with experiments
FEM-SPH Numerical Simulation of Impact Loading on Floating Laminates
Full text linkThe study of dynamic events such as impact and hydroelastic slamming is of great importance in determining the structural integrity of naval or maritime structures, particularly those made of composite materials. This topic has been investigated by numerous researchers using analytical, experimental, and numerical approaches. In this study, we propose using a hybrid numerical model combining smoothed-particle hydrodynamics (SPH) and the finite element method (FEM) to investigate the impact of external objects on floating laminates. The results show a good agreement with the available experimental data regarding the impact dynamic and some limitations in the damage determination
Investigating the crash-box-structure’s ability to absorb energy
No full textProtection under external loads often requires the use of energy absorbers. They are designed to absorb impact energy in a controlled way protecting the structures, as well as their possible occupants. This study examines the crushing performances of thin structures, made in sheet metal, as their shape and thickness vary. Three crash-box-structures were considered for their geometries (i.e. rectangular, rectangular with two inclined walls, and truncated pyramidal structures) with two variations in thicknesses (i.e. s = 1 and 2 mm). Their elastic-plastic behaviour under low-speed compression was analysed by experiments and simulations. The collision force reduction and energy absorption were compared. Based on outcomes a new absorber was developed and used for improving safety in the case of an innovative ultra-light solar racing vehicle
Enhanced Predictive Model for the Mechanical Response of Compression-Loaded Slender Structures
Full text linkThe study of the behavior of thin metal sheets subjected to external loads has always been a matter of great interest due to its numerous theoretical and practical implications. The present analysis aims to investigate how to improve the predictions offered by a numerical model based on the finite element method by considerations on the material properties. Specifically, different modeling alternatives are compared, assessing these choices both with the similar assumptions made by other researchers in the past and with measurements from our own experimentation. The case under consideration consists of a slender, aluminum crash-box structure (a bumper) with a truncated pyramid shape subjected to a concentrated load on the top (axial crushing) up to a 46% reduction in its height. The system is characterized by high deformations (>15%) and large displacements. This presents a complex situation with various nonlinear effects, where the chosen assumptions in material modeling can have significant implications for the results, both in terms of accuracy and computational time. Among the investigated aspects, of no less importance are those related to the appropriate modeling of the elasto-plastic-hardening behavior of the metallic material
GEOMETRY OPTIMIZATION BY FEM SIMULATION OF THE AUTOMATIC CHANGING GEAR
No full textElectro-mechanic devices for the automatic changing of gear were tested by company using the same accelerated life testing procedures in different stages of the product development. All the tested prototypes satisfied the experimental conditions for accelerated life tests, while 50% of components coming from the first sample of serial production showed crack phenomena during the same testing procedure. This situation can be related to a large number of undefined factors: from the variability of material proprieties or in production process parameters to accidentally different conditions in testing. The complete list of all the possibilities of variance was extremely complex to be defined, recognized and verified by new sets of experimental tests. FEM calculation permitted a fast simulation of the component response under the complex experimental testing conditions, modifying the interpretation of some experimental results and correctly driving the designer toward quick improvements of product
Numerical Investigation of Low-Velocity Ice Impact on a Composite Ship Hull Using an FEM/SPH Formulation
No full textIn cold climate regions, ships navigate through diverse ice conditions, making the varied interaction scenarios between hulls and ice critically important. It is crucial to consider the safety and integrity of the hull during an ice-hull interaction, especially in the presence of lightweight structures. Proper design and material selection can help improve the structure's ability to withstand ice forces. Within the scope, understanding the behavior of ice and its interaction with the structure can inform the development of appropriate measures to minimize possible damage or failure. The current study focuses on the interactions occurring during the impact loading phases, which are characteristic of thin first-year ice. A sandwich structure made with carbon fiber-reinforced epoxy prepreg and PVC core was investigated. Low-velocity ice impact was modelled using the Ansys Workbench 2023 R2 and LS-DYNA R11 explicit solver. As the material model, the *MAT055 was chosen based on the literature, while ice was represented with its equation of state. The Tsai Wu criterion was adopted to identify tensile and compressive failure in the matrix and fibers. This simulation allowed us to evaluate how the composite material responds to ice impacts, considering factors such as the speed of the impact, the shape and thickness of the ice, and the properties of the composite material itself
Buckling analysis of telescopic boom: Theoretical and numerical verification of sliding pads
Full text linkWith the aim at improving the highest performances, materials in mechanical structures are constantly pushed closer and closer to their critical limits. Consider, for example, how the progressive reduction in thickness may lead to unforeseen effects in the instability of metal sheets, until the rapid collapse of the whole structure. This risk is specially known by designers of telescopic booms, used for moving aerial platforms. In this paper, by a numerical approach and ANSYS code, structural resistance and stability of a telescopic boom were verified. After a preliminary theoretical analysis, different loads and boundary configurations were considered in accordance with the most common conditions of real utilisation. As general result, it was confirmed that stresses were under the elastic limit of materials, except in a very limited number of contact zones, where specific connecting solutions have to be installed to prevent failures. Furthermore, linear buckling techniques showed that critical loads and corresponding buckling modes were higher than the most extreme working conditions; thus, structural stability was also confirmed. Finally, the large adoption of FEM simulations permitted to reduce the experiments, offering a fast methodology for improvements in design
Technical product risk assessment: Standards, integration in the erm model and uncertainty modeling
Full text linkEuropean Union has accomplished, through introducing New Approach to technical harmonization and standardization, a breakthrough in the field of technical products safety and in assessing their conformity, in such a manner that it integrated products safety requirements into the process of products development. This is achieved by quantifying risk levels with the aim of determining the scope of the required safety measures and systems. The theory of probability is used as a tool for modeling uncertainties in the assessment of that risk. In the last forty years are developed new mathematical theories have proven to be better at modeling uncertainty when we have not enough data about uncertainty events which is usually the case in product development. Bayesian networks based on modeling of subjective probability and Evidence networks based on Dempster-Shafer theory of belief functions proved to be an excellent tool for modeling uncertainty when we do not have enough information about all events aspect
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