scholarly journals Effects of layer shift and yarn path variability on mechanical properties of a twill weave composite

2016 ◽  
Vol 51 (7) ◽  
pp. 913-925 ◽  
Author(s):  
MY Matveev ◽  
AC Long ◽  
LP Brown ◽  
IA Jones

Experimental and numerical analyses of a woven composite were performed in order to assess the effect of yarn path and layer shift variability on properties of the composite. Analysis of the geometry of a 12 K carbon fibre 2 × 2 twill weave at the meso- and macro-scales showed the prevalence of the yarn path variations at the macro-scale over the meso-scale variations. Numerical analysis of yarn path variability showed that it is responsible for a Young’s modulus reduction of 0.5% and CoV of 1% which makes this type of variability in the selected reinforcement almost insignificant for an elastic analysis. Finite element analysis of damage propagation in laminates with layer shift showed good agreement with the experiments. Both numerical analysis and experiments showed that layer shift has a strong effect on the shape of the stress–strain curve. In particular, laminates with no layer shift tend to exhibit a kink in the stress–strain curve which was attributed solely to the layer configuration.

Author(s):  
H. R. Millwater ◽  
S. V. Harren ◽  
B. H. Thacker

Abstract This paper presents a methodology for analyzing structures with random stress-strain behavior. Uncertainties in the stress-strain curve of a structure are simulated by letting a small number of engineering parameters which describe the stress-strain curve be random. Certain constraints are imposed on the engineering parameters in order to have a physically realizable material. A general procedure to handle correlation among the stress-strain parameters has also been developed. This methodology has been integrated into the NESSUS (Numerical Evaluation of Stochastic Structures Under Stress) probabilistic structural analysis system. With this system, probabilistic finite element analysis of structures with random stress-strain behavior can be analyzed in an accurate, automated fashion. An example problem is presented to demonstrate the capabilities of the code. The problem analyzed is that of a pressure vessel fabricated with a material exhibiting random stress-strain behavior.


1981 ◽  
Vol 16 (2) ◽  
pp. 107-110 ◽  
Author(s):  
J Margetson

A uniaxial stress/strain curve is represented empirically by a modified Ramberg-Osgood equation ∊=(σ/E) + (σ/σo)m. Firstly E is extracted then σo and m are determined from two points on the experimental curve. These values are improved iteratively by a least squares fit using all the experimental points on the curve. The procedure is used to generate stress/strain relationships for a variety of materials and there is good agreement with the experimental values. The method is also applied to a simulated aerodynamic heating experiment.


Author(s):  
Pasqualino Corigliano

Industries have shown interest in the use of dissimilar metals to make corrosion-resistant materials combined with good mechanical properties in marine environments. Explosive welding can be considered a good method for joining dissimilar materials to prevent galvanic corrosion. The aim of the present study was to simulate the non-linear behaviour of a Ti6Al4V/Inconel 625 welded joint obtained by explosion welding from the values of the tensile ultimate strength and yielding strength of the parent materials. The present study compared the stress-strain curve from tensile loading obtained by the non-linear finite element analysis with the experimental stress-strain curve of a bimetallic joint. The applied method provides useful information for the development of models and the prediction of the structural behaviour of Ti6Al4V/Inconel 625 explosive welded joints.


2018 ◽  
Vol 185 ◽  
pp. 00020
Author(s):  
Tung-Sheng Yang ◽  
Jhong -Yuan Li

The process of precision forging has been developed recently because of its advantages of giving high production rates and improved strength. For complete filling up, predicting the power requirement and final shape are important features of the forging process. A finite element method is used to investigate the forging force, the final shape and the stress distribution of the parking sensor shell forging. The stress-strain curve of AL-6082 is obtained by the computerized screw universal testing machine. The friction factor between AL-6082 alloy and die material (SKD11) are determined by using ring compression test. Stress-strain curve and fiction factor are then applied to the finite element analysis of the parking sensor shell forging. Maximum forging load, effective stress distribution and shape dimensions are determined of the parking sensor shell forging, using the finite element analysis. Then the parking sensor shells are formed by the forging machine. Finally, the experimental data are compared with the results of the current simulation for the forging force and shape dimensions of the parking sensor shell.


2017 ◽  
Vol 09 (03) ◽  
pp. 1750038 ◽  
Author(s):  
Xiaofeng Lu ◽  
Chaojie Wang ◽  
Gang Li ◽  
Yang Liu ◽  
Xiaolei Zhu ◽  
...  

The finite element analysis (FEA) of porous NiTi shape memory alloys (SMAs) remains a challenge due to irregularity and complexity of pore structure. In this paper, the real finite element model (FEM) is established based on the geometrical reconstruction. Through a SMA constitutive model, the mechanical behavior and stress-induced martensitic (SIM) phase transformation are analyzed with the real FEM. The results show that the stress–strain curve of FEA is in good agreement with the experimental curve and the calculation can reflect the mechanical behavior well in the compressive process. With the increase of load, the SIM first appears pore walls or weak parts of struts, then spreads to the center of matrix, and finally happens to most of matrix. When the slope of the stress–strain curve shows obvious changes, the SIM has happened in quite a part of matrix.


2009 ◽  
Vol 79-82 ◽  
pp. 1297-1300 ◽  
Author(s):  
Hyup Jae Chung ◽  
Kyong Yop Rhee ◽  
Beom Suck Han ◽  
Yong Mun Ryu

In this study, finite element analysis was made to predict the tensile and compressive behaviors of aluminum foam material. The predicted tensile and compressive behaviors were compared with those determined from the tensile and compressive tests. X-ray imaging technique was used to determine internal structure of aluminum foam material. That is, X-ray computed tomography (CT) was used to model the porosities of the material. Three-dimensional finite element modeling was made by stacking two-dimensional tomography of aluminum foam material determined from CT images. The stackings of CT images were processed by three-dimensional modeling program. The results showed that the tensile stress-strain curve predicted from the finite element analysis was similar to that determined by the experiment. The simulated compressive stress-strain curve also showed similar tendency with that of experiment up to about 0.4 strain but exhibited a different behavior from the experimental one after 0.4 strain. The discrepancy of compressive stress-strain curves in a high strain range was associated with the contact of aluminum foam walls broken by the large deformation.


2006 ◽  
Vol 302-303 ◽  
pp. 536-542
Author(s):  
Jian Yin ◽  
Yi Jin Li ◽  
Xiong Zhang ◽  
Shi Qiong Zhou

In this paper, full-range compression tests were conducted on prisms of Old concrete, New-Old concrete and High-Performance Rapid Repair Concrete (HPRRC) prisms The complete stress-strain curve of HPRRC incorporating PFAC (pulverized fly ash composite), Old concrete and New-Old concrete were obtained and compared with each other. The essential uniform deformation capacity of three kinds of concrete was verified with the experimental results. At the same time, the unified numerical expressions of the compressive complete stress-strain curves of the three kinds of concrete are put forward. The theoretical curves from calculation are in good agreement with the experimental curves.


2021 ◽  
Vol 901 ◽  
pp. 170-175
Author(s):  
Tung Sheng Yang ◽  
Ting Fu Zhang ◽  
Tung Wei Lin ◽  
Can Xun Zhang

Bipolar plate is the key component of proton exchange membrane fuel cells. Due to the factors of rapid and mass production, the stamping process is selected to manufacture the bipolar metal plates. First, the stress-strain curve is performed by universal material testing machine.The stress-strain curve is necessary for bipolar plate stamping simultion. The maximum forging load and effective stress distribution of bipolar plate stamping are determined by finite element analysis. Finally, the effect of the traditional crank stamping on the flatness and section thickness of stainless steel bipolar plate are observed by experiments.


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