scholarly journals Application of Failure Criteria on Plywood under Bending

Polymers ◽  
2021 ◽  
Vol 13 (24) ◽  
pp. 4449
Author(s):  
Miran Merhar

In composite materials, the use of failure criteria is necessary to determine the failure forces. Various failure criteria are known, from the simplest ones that compare individual stresses with the corresponding strength, to more complex ones that take into account the sign and direction of the stress, as well as mutual interactions of the acting stresses. This study investigates the application of the maximum stress, Tsai-Hill, Tsai-Wu, Puck, Hoffman and Hashin criteria to beech plywood made from a series of plies of differently oriented beech veneers. Specimens were cut from the manufactured boards at various angles and loaded by bending to failure. The mechanical properties of the beech veneer were also determined. The specimens were modelled using the finite element method with a composite modulus and considering the different failure criteria where the failure forces were calculated and compared with the measured values. It was found that the calculated forces based on all failure criteria were lower than those measured experimentally. The forces determined using the maximum stress criterion showed the best agreement between the calculated and measured forces.

Polymers ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 818 ◽  
Author(s):  
Sarah David Müzel ◽  
Eduardo Pires Bonhin ◽  
Nara Miranda Guimarães ◽  
Erick Siqueira Guidi

The use of composite materials in several sectors, such as aeronautics and automotive, has been gaining distinction in recent years. However, due to their high costs, as well as unique characteristics, consequences of their heterogeneity, they present challenging gaps to be studied. As a result, the finite element method has been used as a way to analyze composite materials subjected to the most distinctive situations. Therefore, this work aims to approach the modeling of composite materials, focusing on material properties, failure criteria, types of elements and main application sectors. From the modeling point of view, different levels of modeling—micro, meso and macro, are presented. Regarding properties, different mechanical characteristics, theories and constitutive relationships involved to model these materials are presented. The text also discusses the types of elements most commonly used to simulate composites, which are solids, peel, plate and cohesive, as well as the various failure criteria developed and used for the simulation of these materials. In addition, the present article lists the main industrial sectors in which composite material simulation is used, and their gains from it, including aeronautics, aerospace, automotive, naval, energy, civil, sports, manufacturing and even electronics.


2001 ◽  
Vol 124 (1) ◽  
pp. 65-70 ◽  
Author(s):  
S. Sriram ◽  
C. J. Van Tyne

Spherical dies are increasing in popularity in the cold-forming industry because of the ease in subsequent secondary operations. This paper presents criteria curves, calculated using the finite element method, to avoid central bursting or internal chevrons in forward extrusions through spherical dies. Critical values of mean stress at the centerline of the extrusion are used as failure criteria to distinguish between acceptable and unacceptable die designs. These failure criteria are conservative in that the critical step for central bursting is considered to be the formation of a microvoid during extrusion, rather than linking of the voids during continued deformation. The resulting process criteria curves are conservative estimates of internal chevron formation during extrusion through spherical dies.


2019 ◽  
Vol 109 ◽  
pp. 00093 ◽  
Author(s):  
Olena Slashchova ◽  
Ihor Slashchov ◽  
Iryna Sapunova

The article is devoted to development of methods for geofiltration calculations with taking into account peculiarities of changes of the rock physical and mechanical properties at water saturation. Methods: mathematical modeling of geomechanical and filtration processes with the help of finite element method and laboratory and underground studies. A mathematical model was formulated for solving a problem of elasticity theory by the finite element method, which took into account peculiarities of water-saturated rocks. Pattern of stress-strain state changing in the fractured water-saturated rocks under the action of critical loads, which occurred around the preparatory roadways during their operation, were established. In order to solve the filtration problems, a bank of collected initial data on physical and mechanical properties of water-saturated rocks was processed with the help of variation coefficients, which were taken into account by the method, which assumed calculation of the model loading with critical parameters.


2009 ◽  
Vol 424 ◽  
pp. 113-119 ◽  
Author(s):  
Jerome Muehlhause ◽  
Sven Gall ◽  
Sören Müller

Extrusion of composite materials can offer big advantages. In this work the manufacturing of a hybrid metal profile in a single production step was investigated. A porthole die was used, thus producing profiles with extrusion seams. Along the seams a material mix up was visible. The extrusion process was simulated with the Finite Element Method to investigate the material flow in die and welding chamber in order to understand the cause for the defects at the seams.


2018 ◽  
Vol 15 (06) ◽  
pp. 1850054 ◽  
Author(s):  
Nicholas Fantuzzi ◽  
Lorenzo Leonetti ◽  
Patrizia Trovalusci ◽  
Francesco Tornabene

Cosserat continua demonstrated to have peculiar mechanical properties, with respect to classic Cauchy continua, because they are able to more accurately describe heterogeneous materials, as particle composites and masonry-like material, taking into account size effects. Many studies have been devoted to their numerical implementation. In this paper, some reference benchmarks, referred to an isotropic heterogeneous sample, are shown by comparing the solutions provided by strong and weak formulations. The strong formulation finite element method (SFEM), implemented in MATLAB®, is compared to the finite element method (FEM), given by COMSOL® Multiphysics, and the advantages of the two approaches are highlighted and discussed.


2020 ◽  
Vol 17 (6) ◽  
pp. 579-587
Author(s):  
Kunlapat THONGKAEW ◽  
Thanwit NAEMSAI

Over the years, plastic water bottle manufacturing, especially PET (Polyethylene terephthalate) bottle has been steadily increasing due to its toughness, transparency, and chemical properties. However, most manufacturers have to spare time, and cost, verifying their prototypes in accordance to the Thai Industrial Standard (TIS) before any mass production can start. This paper aims to overcome some of these problems by using Finite Element Method (FEM) to study bottle mechanical properties, particularly maximum stress and deformation that can be employed to evaluate performance and optimal thickness. From simulation results the optimal thickness of a 6-liter bottle, that its maximum stress can still be kept under critical value, is 0.45 mm. The thinner and lighter bottle reduces the amount of material usage. The FEM simulation also speeds up and alleviates some necessary testing procedures in a prototype designing process.


2019 ◽  
Vol 252 ◽  
pp. 07007 ◽  
Author(s):  
Robert Karpiński ◽  
Łukasz Jaworski ◽  
Józef Jonak ◽  
Przemysław Krakowski

The article presents the results of a preliminary study on the structural analysis of the knee joint, considering changes in the mechanical properties of the articular cartilage of the joint. Studies have been made due to the need to determine the tension distribution occurring in the cartilage of the human knee. This distribution could be the starting point for designing custom made human knee prosthesis. Basic anatomy, biomechanical analysis of the knee joint and articular cartilage was introduced. Based on a series of computed tomography [CT] scans, the 3D model of human knee joint was reverse-engineered, processed and exported to CAD software. The static mechanical analysis of the knee joint model was conducted using the finite element method [FEM], in three different values of tibiofemoral angle and with varying mechanical properties of the cartilage tissue. Main conclusions of the study are: the capability to absorb loads by articular cartilage of the knee joint is preliminary determined as decreasing with increasing degenerations of the cartilage and with age of a patient. Without further information on changes of cartilage’s mechanical parameters in time it is hard to determine the nature of relation between mentioned capability and these parameters.


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