scholarly journals Effect of Strain Rate on the Tensile Mechanical Properties of Electron Beam Welded OFE Copper and High-Purity Niobium for SRF Applications

2021 ◽  
Author(s):  
J.-F. Croteau ◽  
M. Peroni ◽  
S. Atieh ◽  
N. Jacques ◽  
E. Cantergiani
Keyword(s):  
Mechanical Properties ◽  
Electron Beam ◽  
Yield Stress ◽  
High Purity ◽  
High Speed ◽  
Strain Rates ◽  
High Speed Forming ◽  
Elongation To Failure ◽  
Ofe Copper ◽  
Srf Cavities

AbstractAn investigation of the tensile mechanical properties of electron beam welded OFE copper and high-purity niobium sheets is presented. Specimens were deformed in tension at strain rates ranging from 10−3 to ~ 1600 s−1. The 0.2% yield stress and ultimate tensile strength (UTS) of the welded niobium specimens are similar to those of unwelded specimens at strain rates lower or equal to 20 s−1. At higher strain rates, these mechanical properties are lower for welded niobium specimens. The 0.2% yield stress of welded OFE copper specimens is consistently lower than unwelded specimens over the range of strain rates studied, while the UTS is comparable at all strain rates. The elongation to failure of welded OFE copper specimens remains unchanged at all strain rates while the ductility of niobium specimens reduces at strain rates greater or equal to 20 s−1 and reaches a minimum at ~ 400 s−1. The effects of the weld on a non-standardized short specimen geometry, developed for this study to obtain strain rates in the order of 103 s−1, are more pronounced for niobium due to large grain sizes (up to 1200 μm) in the fusion region. However, comparable strength and ductility trends, with respect to a standard specimen, were measured at low strain rates. The conservation of strength and the relatively high ductility of the welded sheets, especially for OFE copper, suggest that bent and electron beam welded tubes could be used for the fabrication of seamless superconducting radiofrequency (SRF) cavities. These results are promising for the use of high-speed forming techniques, like electro-hydraulic forming, for the manufacturing of parts using welded tubes and sheets.

INVESTIGATING THE INFLUENCE OF ENVIRONMENTAL CONDITIONING ON EPOXY RESINS AT QUASISTATIC AND HIGH STRAIN RATES FOR MATERIAL OPERATING LIMIT

2021 ◽  
Author(s):  
SAGAR M. DOSHI, SAGAR M. DOSHI, ◽  
NITHINKUMAR MANOHARAN ◽  
BAZLE Z. (GAMA) HAQUE, ◽  
JOSEPH DEITZEL ◽  
JOHN W. GILLESPIE, JR.
Keyword(s):  
Mechanical Properties ◽  
Epoxy Resin ◽  
Yield Stress ◽  
High Strain ◽  
Operating Conditions ◽  
Strain Rates ◽  
High Strain Rates ◽  
Stress Strain ◽  
Wide Range ◽  
Environmental Aging

Epoxy resin-based composite panels used for armors may be subjected to a wide range of operating temperatures (-55°C to 76°C) and high strain rates on the order of 103-104 s-1. Over the life cycle, various environmental factors also affect the resin properties and hence influence the performance of the composites. Therefore, it is critical to determine the stress-strain behavior of the epoxy resin over a wide range of strain rates and temperatures for accurate multi-scale modeling of composites and to investigate the influence of environmental aging on the resin properties. Additionally, the characterization of key mechanical properties such as yield stress, modulus, and energy absorption (i.e. area under the stress-strain curve) at varying temperatures and moisture can provide critical data to calculate the material operating limits. In this study, we characterize mechanical properties of neat epoxy resin, SC-15 (currently used in structural armor) and RDL-RDC using uniaxial compression testing. RDL-RDC, developed by Huntsman Corporation, has a glass transition temperature of ~ 120°C, compared to ~ 85°C of SC-15. A split Hopkinson pressure bar is used for high strain rate testing. Quasistatic testing is conducted using a screw-driven testing machine (Instron 4484) at 10-3 s-1 and 10-1 s-1 strain rates and varying temperatures. The yield stress is fit to a modified Eyring model over the varying strain rates at room temperature. For rapid investigation of resistance to environmental aging, accelerated aging tests are conducted by immersing the specimens in 100°C water for 48 hours. Specimens are conditioned in an environmental chamber at 76 °C and 88% RH until they reach equilibrium. Tests are then conducted at five different temperatures from 0°C to 95°C, and key mechanical properties are then plotted vs. temperature. The results presented are an important step towards developing a methodology to identify environmental operating conditions for composite ground vehicle applications.

The Methodic of Testing Using Experimental Equipment

2014 ◽  
Vol 635 ◽  
pp. 94-99
Author(s):  
Martin Kubelka ◽  
Tomáš Pačák ◽  
František Tatíček
Keyword(s):  
Mechanical Properties ◽  
Strain Rate ◽  
High Speed ◽  
Mechanical Engineering ◽  
Manufacturing Technology ◽  
Strain Rates ◽  
Experimental Equipment ◽  
Material Behaviour ◽  
Pressing Process ◽  
Engineering Institute

During pressing using high speed, the material is stressed to the limit of its mechanical properties. And this generates problems during production. For this reason, opens debate on the factors previously neglected, such as the strain rate. For determining the effect of strain rate on the pressing process has been designed to CTU, Faculty of Mechanical Engineering, Institute of Manufacturing Technology, equipment for monitoring the behaviour of the material at different strain rates. The article describes the creation of testing methodologies material behaviour using this device.

TEM -analysis of the BeO-dispersion in high purity Be-ingots

1978 ◽  
Vol 36 (1) ◽  
pp. 636-637
Author(s):  
Hans Migge
Keyword(s):  
Mechanical Properties ◽  
Electron Beam ◽  
Oxide Scale ◽  
High Purity ◽  
Ultrahigh Vacuum ◽  
Particle Sizes ◽  
Tem Analysis ◽  
Tremendous Importance ◽  
Thin Oxide ◽  
To Come

Inclusions of BeO are of tremendous importance on the mechanical properties of Beryllium [1,2]. The BeO particle sizes of different hot pressed materials are in the range between 400 Å and 10 μm for BeO contents between 0.5 and 3.6%[3]. However, there is no investigation about the BeO dispersion in high purity (<200 ppm BeO) ingots. Information on this subject should be derived from the diffuse Debye rings of BeO, which as yet are thought to come from the very thin oxide scale on the Be-surface [3].0.1 mm foils of Berylco IF—1 from KBI with BeO < 200 ppm were analyzed at 100 kV in the as received condition or after annealing for 1 hour at 900°C in ultrahigh vacuum. With the electron beam parallel to [00.1], [11.1], [02.1], [12.1], [03.1], [12.2] (using different grains) always four diffuse BeO rings of the type {10.0}, {10.1}, {11.0}and the unresolved {20.0}/{11.2} appear in the SAD-pattern.

scholarly journals A Laboratory-Scale Instrumented Forging Hammer as an Intermediate Strain Rate Testing Device

2021 ◽  
Vol 250 ◽  
pp. 01002
Author(s):  
Julen Agirre ◽  
Borja Erice ◽  
David Abedul ◽  
Eneko Saenz de Argandoña ◽  
Nagore Otegi ◽  
...  
Keyword(s):  
High Speed ◽  
Computational Models ◽  
Split Hopkinson Pressure Bar ◽  
Material Model ◽  
Industrial Applications ◽  
Strain Rates ◽  
Hopkinson Pressure Bar ◽  
Mechanical Characterisation ◽  
High Speed Forming ◽  
Split Hopkinson

Mechanical characterisation of metallic materials at intermediate strain rates is essential to calibrate and validate computational models for industrial applications such as high-speed forming processes i.e. hammer forging, blanking, forming, etc. The most common devices that perform medium to high loading rate experiments are the servo-hydraulic universal testing machines and Split Hopkinson bar systems. Here we analyse the possibility of employing an in-house designed and constructed DirectImpact Drop Hammer (DIDH) for material mechanical characterisation at medium strain rates, ranging from 100 to 300 s-1. To show the suitability of the DIDH for mechanical characterisation, uniaxial compression experiments on S235JR structural steel are conducted and compared with finite element (FE) simulations performed with an elasticthermoviscoplastic material model previously calibrated with Split Hopkinson Pressure Bar (SHPB) tests.

Compression Tests of High Strength Steels

2008 ◽  
Vol 59 ◽  
pp. 293-298
Author(s):  
Vaclav Mentl ◽  
Josef Bystricky
Keyword(s):  
Mechanical Properties ◽  
Mechanical Testing ◽  
High Speed ◽  
Dynamic Compression ◽  
Testing Machine ◽  
High Strength Steels ◽  
High Strength ◽  
Strain Rates ◽  
Compression Tests ◽  
Impact Compression

Mathematical modelling and virtual testing of components and structures represent a useful and economic tool for design and safety assessment. The basic mechanical properties which can be found in material standards are not relevant in cases where the real service conditions differ from those applied during standardised testing. Thus e.g. mechanical behaviour at higher strain rates can be interesting for the car components when the simulation of crash situations is used during structure development. The dynamic compression tests are usually performed by means of drop towers, by means of high speed hydraulic testing machines or Hopkinson bar method. At the Mechanical Testing Laboratory of the SKODA Research Inst. in Pilsen, Czech Republic, an instrumentation of Charpy pendulum testing machine was realised in order that it was possible to perfom dynamic compression tests, [1], and the compatibility of obtained results in comparison with traditional impact compression tests was verified within the round–robin carried out by TC5 ESIS Sub-Committee on “Mechanical Testing at Intermediate Strain Rates“, [2]. A new striking tup and load measurement system were designed and callibrated. At the same time, a new software was developed which makes it possible to evaluate the test force-deformation record. The goal of this study was 1. to check the possibility of compression testing of high strength materilas by mens of Charpy pendulum, and 2. to study the strain rate influence on basic mechanical properties.

Effect of beam current on the microstructure, crystallographic texture and mechanical properties of electron beam welded high purity niobium

2021 ◽  
pp. 111318
Author(s):  
Kalyan Das ◽  
Abhishek Ghosh ◽  
Avisor Bhattacharya ◽  
Harishchandra Lanjewar ◽  
Jyotsna Dutta Majumdar ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Electron Beam ◽  
High Purity ◽  
Crystallographic Texture ◽  
Beam Current

Influence of Deformation Rate on Mechanical Response of an AISI 316L Austenitic Stainless Steel

2014 ◽  
Vol 922 ◽  
pp. 49-54
Author(s):  
Mattias Calmunger ◽  
Guo Cai Chai ◽  
Sten Johansson ◽  
Johan Moverare
Keyword(s):  
Mechanical Properties ◽  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Dynamic Recrystallization ◽  
Strain Rate ◽  
Power Plants ◽  
Elevated Temperatures ◽  
Strain Rates ◽  
Aisi 316L ◽  
Elongation To Failure

Austenitic stainless steels are often used for components in demanding environment. These materials can withstand elevated temperatures and corrosive atmosphere like in energy producing power plants. They can be plastically deformed at slow strain rates and high alternating or constant tensile loads such as fatigue and creep at elevated temperatures. This study investigates how deformation rates influence mechanical properties of an austenitic stainless steel. The investigation includes tensile testing using strain rates of 2*10-3/ and 10-6/s at elevated temperatures up to 700°C. The material used in this study is AISI 316L. When the temperature is increasing the strength decreases. At a slow strain rate and elevated temperature the stress level decreases gradually with increasing plastic deformation probably due to dynamic recovery and dynamic recrystallization. However, with increasing strain rate elongation to failure is decreasing. AISI 316L show larger elongation to failure when using a strain rate of 10-6/s compared with 2*10-3/s at each temperature. Electron channelling contrast imaging is used to characterize the microstructure and discuss features in the microstructure related to changes in mechanical properties. Dynamic recrystallization has been observed and is related to damage and cavity initiation and propagation.

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