Mechanical Response of Ti-6Al-4V Alloy on Deformation at Moderate Temperatures

2013 ◽  
Vol 549 ◽  
pp. 311-316 ◽  
Author(s):  
Marion Merklein ◽  
Hinnerk Hagenah ◽  
Markus Kaupper ◽  
Adam Schaub
Keyword(s):  
Titanium Alloy ◽  
Elevated Temperatures ◽  
Mechanical Response ◽  
Material Behavior ◽  
High Yield ◽  
Uniaxial Tensile ◽  
Uniaxial Tensile Test ◽  
Forming Process ◽  
Element Analysis ◽  
Specific Strength

Due to beneficial characteristics such as high specific strength, corrosion resistance and biocompatibility Ti-6Al-4V alloy has become the most important industrially produced titanium alloy during the last decades. Commonly used for aerospace technology and medical products, nowadays Ti-6Al-4V covers 50% of the worldwide produced titanium alloy parts. Different deformation operations as forging and casting as well as machining are used to shape titanium alloy components. For sheet metals, cost and time of fabrication can be reduced significantly via the near net shape technology sheet metal forming. Materials such as the α + β alloy Ti-6Al-4V with high yield stress and comparatively low elastic modules need to be formed at elevated temperatures to increase their formability. Numerical simulations are applied to calculate the forming behavior during the process and conclude the characteristics of the shaped part. Therefore in this paper the mechanical behavior of this titanium alloy is investigated by uniaxial tensile test within elevated temperatures ranging from 250 to 500 °C. Finally, the experimental results are adapted to models which predict the flow response in order to describe material behavior in finite element analysis of the forming process.

Finite Element Analysis on Nitinol Medical Applications

2002 ◽  
Author(s):  
Xiao-Yan Gong ◽  
Alan R. Pelton
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Material Behavior ◽  
Nonlinear Material ◽  
Uniaxial Tensile ◽  
Uniaxial Tensile Test ◽  
Element Analysis ◽  
Highly Nonlinear ◽  
Device Applications ◽  
Specific Material

Nitinol, an alloy of about 50% Ni and 50% Ti, is a very unique material. At constant temperature above its Austenite finish (Af) temperature, under uniaxial tensile test, the material is highly nonlinear and capable of large deformation to the ultimate strain on the order of 15%. This material behavior, known as superelasticity, along with its excellent biocompatibility and corrosion resistance, makes Nitinol a perfect material candidate for many medical device applications. However, the nonlinear material response also requires a specific material description to perform the stress analysis. The user developed material subroutine from HKS/West makes the simulation of the Nitinol devices possible. This article presents two case studies of the nonlinear finite element analysis using ABAQUS/Standard and the Nitinol UMAT.

Hydro-Mechanical Deep Drawing Simulation and Preparation of Novel Al-Li Alloy Irregular Cups

2015 ◽  
Vol 1089 ◽  
pp. 337-340
Author(s):  
Juan Ling ◽  
Hua Guan Li ◽  
Jie Tao ◽  
Xun Zhong Guo ◽  
Hui Wang ◽  
...  
Keyword(s):  
Thickness Distribution ◽  
True Stress ◽  
Experimental Results ◽  
Uniaxial Tensile ◽  
Uniaxial Tensile Test ◽  
Forming Process ◽  
Element Analysis ◽  
Aluminum Lithium Alloy ◽  
Analysis Technique ◽  
Aluminum Lithium

The true stress-strain curves of 2198-T3 aluminum-lithium alloy in three different orientations (0°,45° and 90°) were measured by uniaxial tensile test. Finite element analysis technique was used to simulate the forming process of irregular cup, and the hydro forming experiments were conducted with YB32-100t press machine. The results showed that the key forming parameter-n values were similar in three orientations. Simulation results illustrated that the thickness of the blank reached the lowest value at the round corner. Experimental results verified friction was a significant factor to manufacture a qualified competent. Meanwhile, the experimental results agreed well with the simulation ones. The practical thickness distribution of 2198-T3 irregular cup along the section line was coincided with simulation.

Investigations on Deformation Behavior of AA5754 Sheet Alloy Under Warm Hydroforming Conditions

2011 ◽  
Vol 133 (5) ◽  
Author(s):  
S. Mahabunphachai ◽  
M. Koc ◽  
J. E. Carsley
Keyword(s):  
Strain Rate ◽  
Biaxial Loading ◽  
Elevated Temperatures ◽  
Material Behavior ◽  
Dome Height ◽  
Uniaxial Tensile ◽  
Process Conditions ◽  
Strain Rates ◽  
Forming Process ◽  
Warm Hydroforming

Material behavior of AA5754 was investigated under different forming process conditions, including two loading conditions (uniaxial tensile and biaxial bulge), several strain rates (constant strain rates at 0.0013 and 0.013/s, and variable strain rate profiles: increasing and decreasing profiles), and several temperature levels (ambient up to 260 °C). Additional warm hydroforming experiments were conducted using a closed-die set up to understand the forming limits of AA5754. The results from tensile and hydraulic bulge tests as well as closed-die hydroforming experiments suggested that, in general, formability of AA5754 can be significantly improved with slow forming rates (<0.02/s), high forming temperature (>200 °C), and biaxial loading (hydroforming) that can delay strain localization (necking). However, the effect of forming rate did not reveal any significant gain in formability for temperatures below 200 °C. The effect of variable strain rate control was found to be significant only at elevated temperatures (>200 °C), where increasing strain rate resulted in lower formability and decreasing strain rate improved the maximum attainable dome height at temperatures above 200 °C. Finally, the material flow curves obtained from the tensile and bulge tests were shown to provide reasonably accurate predictions for cavity filling ratios (∼ 3–15% error) in finite element analyses.

scholarly journals Ability of Constitutive Models to Characterize the Temperature Dependence of Rubber Hyperelasticity and to Predict the Stress-Strain Behavior of Filled Rubber under Different Defor Mation States

Polymers ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 369
Author(s):  
Xintao Fu ◽  
Zepeng Wang ◽  
Lianxiang Ma
Keyword(s):  
Experimental Data ◽  
Temperature Dependence ◽  
Mechanical Response ◽  
Constitutive Models ◽  
Uniaxial Tensile ◽  
Uniaxial Tensile Test ◽  
Chain Model ◽  
Stress Strain ◽  
Filled Rubber ◽  
Yeoh Model

In this paper, some representative hyperelastic constitutive models of rubber materials were reviewed from the perspectives of molecular chain network statistical mechanics and continuum mechanics. Based on the advantages of existing models, an improved constitutive model was developed, and the stress–strain relationship was derived. Uniaxial tensile tests were performed on two types of filled tire compounds at different temperatures. The physical phenomena related to rubber deformation were analyzed, and the temperature dependence of the mechanical behavior of filled rubber in a larger deformation range (150% strain) was revealed from multiple angles. Based on the experimental data, the ability of several models to describe the stress–strain mechanical response of carbon black filled compound was studied, and the application limitations of some constitutive models were revealed. Combined with the experimental data, the ability of Yeoh model, Ogden model (n = 3), and improved eight-chain model to characterize the temperature dependence was studied, and the laws of temperature dependence of their parameters were revealed. By fitting the uniaxial tensile test data and comparing it with the Yeoh model, the improved eight-chain model was proved to have a better ability to predict the hyperelastic behavior of rubber materials under different deformation states. Finally, the improved eight-chain model was successfully applied to finite element analysis (FEA) and compared with the experimental data. It was found that the improved eight-chain model can accurately describe the stress–strain characteristics of filled rubber.

Experimental Investigation of Ti-6Al-4V with a Biaxial Tensile Test Setup at Elevated Temperature

2014 ◽  
Vol 622-623 ◽  
pp. 273-278 ◽  
Author(s):  
Marion Merklein ◽  
Sebastian Suttner ◽  
Adam Schaub
Keyword(s):  
Elevated Temperature ◽  
Elevated Temperatures ◽  
Tensile Tests ◽  
Advanced Materials ◽  
Uniaxial Tensile ◽  
Plastic Yielding ◽  
Characterization Methods ◽  
Specific Strength ◽  
Biaxial Tensile ◽  
Stress States

The requirement for products to reduce weight while maintaining strength is a major challenge to the development of new advanced materials. Especially in the field of human medicine or aviation and aeronautics new materials are needed to satisfy increasing demands. Therefore the titanium alloy Ti-6Al-4V with its high specific strength and an outstanding corrosion resistance is used for high and reliable performance in sheet metal forming processes as well as in medical applications. Due to a meaningful and accurate numerical process design and to improve the prediction accuracy of the numerical model, advanced material characterization methods are required. To expand the formability and to skillfully use the advantage of Ti-6Al-4V, forming processes are performed at elevated temperatures. Thus the investigation of plastic yielding at different stress states and at an elevated temperature of 400°C is presented in this paper. For this reason biaxial tensile tests with a cruciform shaped specimen are realized at 400°C in addition to uniaxial tensile tests. Moreover the beginning of plastic yielding is analyzed in the first quadrant of the stress space with regard to complex material modeling.

scholarly journals Performance of Thermo-Mechanically Processed AA7075 Alloy at Elevated Temperatures—From Microstructure to Mechanical Properties

Metals ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 884 ◽  
Author(s):  
Seyed Vahid Sajadifar ◽  
Emad Scharifi ◽  
Ursula Weidig ◽  
Kurt Steinhoff ◽  
Thomas Niendorf
Keyword(s):  
Mechanical Properties ◽  
Elevated Temperatures ◽  
Tensile Tests ◽  
Uniaxial Tensile ◽  
Forming Process ◽  
Softening Mechanism ◽  
Rate Dependent ◽  
Heat Treated ◽  
Different Temperatures ◽  
Die Forming

This study focuses on the high temperature characteristics of thermo-mechanically processed AA7075 alloy. An integrated die forming process that combines solution heat treatment and hot forming at different temperatures was employed to process the AA7075 alloy. Low die temperature resulted in the fabrication of parts with higher strength, similar to that of T6 condition, while forming this alloy in the hot die led to the fabrication of more ductile parts. Isothermal uniaxial tensile tests in the temperature range of 200–400 °C and at strain rates ranging from 0.001–0.1 s−1 were performed on the as-received material, and on both the solution heat-treated and the thermo-mechanically processed parts to explore the impacts of deformation parameters on the mechanical behavior at elevated temperatures. Flow stress levels of AA7075 alloy in all processing states were shown to be strongly temperature- and strain-rate dependent. Results imply that thermo-mechanical parameters are very influential on the mechanical properties of the AA7075 alloy formed at elevated temperatures. Microstructural studies were conducted by utilizing optical microscopy and a scanning electron microscope to reveal the dominant softening mechanism and the level of grain growth at elevated temperatures.

The Test of Aircraft Material with Performance Parameters

2014 ◽  
Vol 540 ◽  
pp. 48-51
Author(s):  
Xia Ren ◽  
Lian Xiang Ma
Keyword(s):  
Large Scale ◽  
Plastic Material ◽  
Uniaxial Tensile ◽  
Uniaxial Tensile Test ◽  
Performance Parameters ◽  
Analysis Software ◽  
Element Analysis ◽  
Aircraft Material ◽  
Yeoh Model ◽  
Experimental Data Analysis

This paper uses the ABAQUS finite element analysis software for modeling and nonlinear analysis of aircraft tires. Paper H44.5 × 16.5-21 aviation tires, The plastic material of the tire subjected to uniaxial stretching to obtain a rubber such as Young's modulus, Poisson's ratio of the material parameters. Uniaxial tensile test tests the tensile properties of the rubber, the use of large-scale numerical calculations and fitting analysis of the experimental data analysis software Matlab, Yeoh model mechanical parameters.

An Experimental Investigation Into the High Speed Turning of Ti-6Al-4V Titanium Alloy

2010 ◽  
Author(s):  
Anil K. Srivastava ◽  
Jon Iverson
Keyword(s):  
Titanium Alloy ◽  
Titanium Alloys ◽  
High Speed ◽  
Elevated Temperatures ◽  
Chemical Reactivity ◽  
Specific Strength ◽  
Aerospace Applications ◽  
Layered Coatings ◽  
High Specific Strength ◽  
Cutting Speeds

Titanium and its alloys have seen increased utilization in military and aerospace applications due to combination of high specific strength, toughness, corrosion resistance, elevated-temperature performance and compatibility with polymer composite materials. Titanium alloys are difficult to machine due to their inherent low thermal conductivity and higher chemical reactivity with other materials at elevated temperatures. In general, temperature related machining difficulties are encountered at production speeds in the range of 60 m/min and high-speed machining of these alloys has created considerable interest to researchers, tool manufacturers and end users. This paper provides recent results obtained during turning operation with the aim of improving machinability of titanium alloys. Several tests have been conducted using (i) micro-edge prep geometry of the inserts, (ii) ultra-hard PVD coated, and (iii) nano-layered coated inserts and the effects of speeds and feeds during turning of Ti-6Al-4V titanium alloy are discussed. The initial tests have been conducted under orthogonal (2-D) cutting conditions with no coolant application. Based on these results, several oblique cutting (3-D) tests have been designed and conducted to study the effect of various types of ultra-hard and nano-layered coatings at higher cutting speeds under flooded coolant conditions. The effects of speed and feed on cutting force and tool wear are presented in this paper.

Elasto-Plastic Analysis of a Miniature Circular Disk Bending Specimen

2006 ◽  
Author(s):  
Vishnu Verma ◽  
A. K. Ghosh ◽  
G. Behera ◽  
Kamal Sharma ◽  
R. K. Singh
Keyword(s):  
Plastic Deformation ◽  
Finite Element ◽  
Yield Stress ◽  
Material Properties ◽  
Stable Solution ◽  
Bending Test ◽  
Uniaxial Tensile ◽  
Uniaxial Tensile Test ◽  
Plastic Behavior ◽  
Element Analysis

Miniature disk bending test is used to evaluate the mechanical behavior of irradiated materials and its properties — mainly ductility loss due to irradiation in steel. In Miniature Disk Bending Machine the specimen is firmly held between the two horizontal jaws of punch, and an indentor with spherical ball travels vertically. Researchers have observed reasonable correlations between values of the yield stress, strain hardening and ultimate tensile strength estimated from this test and mechanical properties determined from the uniaxial tensile test. Some methods for the analysis of miniature disk bending, proposed by various authors have been discussed in the paper. It is difficult to distinguish between the regimes of elastic and plastic deformation since local plastic deformation occurs for very small values of load when the magnitude of spatially averaged stress will be well below the yield stress. Also, the analytical solution for large amplitude, plastic deformation becomes rather unwieldy. Hence a finite element analysis has been carried out. The finite element model, considers contact between the indentor and test specimen, friction between various pairs of surfaces and elastic plastic behavior. The load is increased in steps and converged solution has been obtained and analysis terminated at a load beyond which a stable solution cannot be obtained. A sensitivity study has been carried out by varying the various parameters defining the material properties by ±10% around the base values. This study has been carried out to generate a data base for the load-deflection characteristics of similar materials from which the material properties can be evaluated by an inverse calculation. It is seen that the deflection obtained by analytical elastic bending theory is significantly lower than that obtained by the elasto-plastic finite element solution at relatively small values of load. The FE solution and experimental results are in reasonably good agreement.

scholarly journals Analysis of human emboli and thrombectomy forces in large-vessel occlusion stroke

2020 ◽  
pp. 1-9 ◽  
Author(s):  
Yang Liu ◽  
Yihao Zheng ◽  
Adithya S. Reddy ◽  
Daniel Gebrezgiabhier ◽  
Evan Davis ◽  
...  
Keyword(s):  
Glass Tube ◽  
Ultimate Tensile Stress ◽  
Material Behavior ◽  
Large Vessel ◽  
Uniaxial Tensile ◽  
Uniaxial Tensile Test ◽  
Vessel Occlusion ◽  
Cell Percentage ◽  
Uniaxial Tensile Testing ◽  
Custom Made

OBJECTIVEThis study’s purpose was to improve understanding of the forces driving the complex mechanical interaction between embolic material and current stroke thrombectomy devices by analyzing the histological composition and strength of emboli retrieved from patients and by evaluating the mechanical forces necessary for retrieval of such emboli in a middle cerebral artery (MCA) bifurcation model.METHODSEmbolus analogs (EAs) were generated and embolized under physiological pressure and flow conditions in a glass tube model of the MCA. The forces involved in EA removal using conventional endovascular techniques were described, analyzed, and categorized. Then, 16 embolic specimens were retrieved from 11 stroke patients with large-vessel occlusions, and the tensile strength and response to stress were measured with a quasi-static uniaxial tensile test using a custom-made platform. Embolus compositions were analyzed and quantified by histology.RESULTSUniaxial tension on the EAs led to deformation, elongation, thinning, fracture, and embolization. Uniaxial tensile testing of patients’ emboli revealed similar soft-material behavior, including elongation under tension and differential fracture patterns. At the final fracture of the embolus (or dissociation), the amount of elongation, quantified as strain, ranged from 1.05 to 4.89 (2.41 ± 1.04 [mean ± SD]) and the embolus-generated force, quantified as stress, ranged from 63 to 2396 kPa (569 ± 695 kPa). The ultimate tensile strain of the emboli increased with a higher platelet percentage, and the ultimate tensile stress increased with a higher fibrin percentage and decreased with a higher red blood cell percentage.CONCLUSIONSCurrent thrombectomy devices remove emboli mostly by applying linear tensile forces, under which emboli elongate until dissociation. Embolus resistance to dissociation is determined by embolus strength, which significantly correlates with composition and varies within and among patients and within the same thrombus. The dynamic intravascular weakening of emboli during removal may lead to iatrogenic embolization.

Sign in / Sign up

Export Citation Format

Share Document