High Strain, High Strain Rate Forming of Difficult to Deform Tubular Parts

2009 ◽  
Vol 131 (6) ◽  
Author(s):  
K. Kluz ◽  
E. S. Geskin
Keyword(s):  
Tensile Strength ◽  
High Strain Rate ◽  
Strain Rate ◽  
High Strain ◽  
High Energy ◽  
Work Piece ◽  
High Tensile Strength ◽  
Explosive Forming ◽  
High Strain Rate Forming ◽  
Tubular Components

High demand for formed tubular components and the necessity to increase their strength to weight ratio have established a need for new, effective, and low cost forming technologies. This work investigates the application of a propellant-driven water stream to the formation of high tensile strength alloys such as stainless steel 321, Inconel 625, and Ti–3Al–2.5V. The proposed forming technology is based on the utilization of high pressure developed in liquid flowing through a tubular work piece. This pressure results from superposition of compression waves generated in the course of the impact of the liquid by products of propellant combustion. An experimental setup, used for the study of the technology in question, consisted of a tubular component, inserted into a split die assembly, and a combustion chamber, which generated gas, driving water through a work piece. This setup was successfully used for high strain, high strain rate forming of tubular components. In particular, the formation of various shapes in the course of an expansion of seamless tubing was examined. Despite large strains, exceeding in some cases the static test elongation limit, the generated samples were characterized by a uniform wall thinning and structural integrity. For example, a 55% expansion of Ti–3Al–2.5V tube was attained using a simple setup. The acquired experimental data show that the technology can be applied to form alloys characterized by high tensile strength, low static elongation limits, and low modulus of elasticity. Simplicity and low capital cost of the process determine its competitiveness in comparison to conventional quasistatic hydroexpansion, hot forming, and high-energy rate explosive forming processes.

scholarly journals An Image-Based Impact Test for the High Strain Rate Tensile Properties of Brittle Materials

2018 ◽  
Vol 183 ◽  
pp. 02042
Author(s):  
Lloyd Fletcher ◽  
Fabrice Pierron
Keyword(s):  
Tensile Strength ◽  
Elastic Modulus ◽  
High Strain Rate ◽  
Strain Rate ◽  
Stress Wave ◽  
High Strain ◽  
Brittle Materials ◽  
Test Method ◽  
Strain Rates ◽  
High Strain Rates

Testing ceramics at high strain rates presents many experimental diffsiculties due to the brittle nature of the material being tested. When using a split Hopkinson pressure bar (SHPB) for high strain rate testing, adequate time is required for stress wave effects to dampen out. For brittle materials, with small strains to failure, it is difficult to satisfy this constraint. Because of this limitation, there are minimal data (if any) available on the stiffness and tensile strength of ceramics at high strain rates. Recently, a new image-based inertial impact (IBII) test method has shown promise for analysing the high strain rate behaviour of brittle materials. This test method uses a reflected compressive stress wave to generate tensile stress and failure in an impacted specimen. Throughout the propagation of the stress wave, full-field displacement measurements are taken, from which strain and acceleration fields are derived. The acceleration fields are then used to reconstruct stress information and identify the material properties. The aim of this study is to apply the IBII test methodology to analyse the stiffness and strength of ceramics at high strain rates. The results show that it is possible to identify the elastic modulus and tensile strength of tungsten carbide at strain rates on the order of 1000 s-1. For a tungsten carbide with 13% cobalt binder the elastic modulus was identified as 516 GPa and the strength was 1400 MPa. Future applications concern boron carbide and sapphire, for which limited data exist in high rate tension.

Tensile strength of aluminum-epoxy resin composite structure under high strain rate conditions

2012 ◽  
Author(s):  
Damien Laporte ◽  
Frederic Malaise ◽  
Michel Boustie ◽  
Jean-Marc Chevalier ◽  
Eric Buzaud
Keyword(s):  
Tensile Strength ◽  
High Strain Rate ◽  
Strain Rate ◽  
Epoxy Resin ◽  
Composite Structure ◽  
High Strain ◽  
Resin Composite ◽  
Epoxy Resin Composite

scholarly journals An Experimental Study on the Dynamic Behavior of an Ultra High-Strength Concrete

2020 ◽  
Vol 10 (12) ◽  
pp. 4170
Author(s):  
Ahmet Reha Gunay ◽  
Sami Karadeniz ◽  
Mustafa Kaya
Keyword(s):  
Compressive Strength ◽  
High Strain Rate ◽  
Strain Rate ◽  
Dynamic Behavior ◽  
High Strength Concrete ◽  
High Strain ◽  
High Strength ◽  
High Energy ◽  
Static Compression ◽  
Strength Concrete

Ultra-high-strength concrete is a newly developed construction material that has a minimum 120 MPa or higher compressive strength. Recently, the usage of high-strength and ultra-high-strength concretes has become widespread due to the enhancement of the concrete technology. Many civil engineering structures constructed by using concrete materials are usually subjected to, in addition to static loads, dynamic loads due to earthquakes, wind and storm, impact and blast, which take place under high energy and high strain rate values. The effects of such loadings on the structure must be understood thoroughly. In recent years, the withstanding of a structure on these loading conditions has become a crucial issue for its impact on the economy and human safety. One of the approaches to fulfill these requirements is to develop high-strength or ultra high-strength concretes (UHSCs). In this study, an ultra-high-strength concrete with a compressive strength of 135 MPa was designed and developed. In order to determine the dynamic behavior of this UHSC, the specimens at three height/diameter ratios (approximately, 0.6, 1.0 and 1.2) were extracted from the prepared concrete mixtures. These concrete specimens were tested to determine both the quasi-static and dynamic compressive behaviors of the developed concrete. In the quasi-static compression tests, cylindrical specimens and a conventional compressive testing machine were used. In order to study the dynamic compressive behavior, a Split Hopkinson Pressure Bar (SHPB) test setup was used. In this test system, the time variations of compressive strength, the strain and strain rates under uniaxial pressure loading were experimentally evaluated and the deformation and fracturing processes of the specimens were recorded using a high-speed camera. The test results, based on the testing of 21 different specimens, have shown that the dynamic compressive strength values of the developed concrete varied in the range of 143 to 253 MPa, while the strain rate values varied in the range of 353 s−1 to 1288 s−1. Using the data generated in the SHPB tests, the parameters present in a Johnson–Holmquist–Cook concrete material model, which is used in numerical studies on the high strain rate behavior of concretes, were evaluated.

scholarly journals High Strain Rate Tensile Properties of Annealed 2 1/4 Cr-1 Mo Steel

1976 ◽  
Vol 98 (4) ◽  
pp. 361-368 ◽  
Author(s):  
R. L. Klueh ◽  
R. E. Oakes
Keyword(s):  
Tensile Strength ◽  
Ultimate Tensile Strength ◽  
High Strain Rate ◽  
Strain Rate ◽  
Tensile Properties ◽  
Elevated Temperatures ◽  
High Strain ◽  
Total Elongation ◽  
Major Effect ◽  
Dynamic Strain

The high strain rate tensile properties of annealed 2 1/4 Cr-1 Mo steel were determined and the tensile behavior from 25 to 566°C and strain rates of 2.67 × 10−6 to 144/s were described. Above 0.1/s at 25°C, both the yield stress and the ultimate tensile strength increased rapidly with increasing strain rate. As the temperature was increased, a dynamic strain aging peak appeared in the ultimate tensile strength-temperature curves. The peak height was a maximum at about 350°C and 2.67 × 10−6/s. With increasing strain rate, a peak of decreased height occurred at progressively higher temperatures. The major effect of strain rate on ductility occurred at elevated temperatures, where a decrease in strain rate caused an increase in total elongation and reduction in area.

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