Extensional Properties of Coating Colors at High Strain Rates

2003 ◽  
Author(s):  
Alfa Arzate ◽  
Gabriel Ascanio ◽  
Pierre J. Carreau ◽  
Philippe A. Tanguy
Keyword(s):  
Shear Viscosity ◽  
High Speed ◽  
High Strain ◽  
Newtonian Fluids ◽  
Extensional Viscosity ◽  
Strain Rates ◽  
High Strain Rates ◽  
Paper Coating ◽  
Trouton Ratio ◽  
The Relationship

Paper coating fluids also called colors are concentrated aqueous suspensions composed mainly of mineral pigments, thickeners, binders and dispersing agents. They are applied onto moving paper web for improving the optical and printing properties. Roll coating is one of the most used technologies for paper coating, however jet coating is currently a promising technology for high-speed processes. Coating colors are submitted to high strain rates in both roll or jet coaters, therefore the extensional viscosity plays a major role in the process. An orifice flowmeter was used for measuring the extensional properties of complex rheology fluids such as coating colors. The principle of this flowmeter is based on the relationship between pressure drop and the flow rate of fluid passing through a small orifice. The flowmeter was firstly calibrated in terms of a dimensionless Euler number as a function of the Reynolds number with Newtonian fluids. The calibration curve was then used to determine the apparent extensional viscosity of coating colors. Results of extensional properties of paper coating colors are presented and compared to shear viscosity. The ratio of extensional to shear viscosity (Trouton ratio) for some coating colors was shown to exceed considerably the theoretical value of 3 expected for Newtonian fluids.

Pb-free PBGA Design Points to Improve Handling Robustness

2012 ◽  
Vol 2012 (1) ◽  
pp. 000110-000118 ◽  
Author(s):  
Isabel de Sousa ◽  
Brian Roggeman ◽  
Oswaldo Chacon ◽  
Niki Spencer ◽  
Mamoru Ueno
Keyword(s):  
High Speed ◽  
Solder Joints ◽  
High Strain ◽  
Strain Rates ◽  
Process Variables ◽  
Flexural Stress ◽  
High Strain Rates ◽  
Ball Shear ◽  
Laminate Design ◽  
Free Solder

Pb-Free BGA solder joints are more brittle and more susceptible to interfacial fails than the leaded versions. These brittle failures typically occur if the modules are subjected to high strain rates through module handling impacts or PCB flexural stress. The high speed ball shear technique is a useful method to submit solder joints to high strain rates in a controlled manner to emulate the levels of strain the BGAs may see in handling. This measurement technique was used to evaluate different laminate design and process variables on organic laminate substrates to create a more robust Pb-Free solder joint. Experiments were conducted to evaluate the effects and interactions of laminate, module assembly process, SAC alloy composition, and thermal treatments. Modulations of shear speed and shear angle made it possible to observe transitions from ductile to brittle solder fractures. The high speed ball shear method was successful to differentiate subtle effects resulting from different design points and process variables. The copper composition in the PbFree solder alloy, thermal history, and geometric factors such as solder volume, solder resist opening and solder resist thickness all had measurable impacts on the shear strength and transition point of ductile to brittle failure. Some BGA configurations have also been tested in reliability, namely in thermal cycling, and were shown to meet application requirements. Optimal design points can therefore be applied to enhance handling robustness without compromising on reliability.

Experimental Studies of the Behaviour at High Strain Rates of Unfilled and Filled Polypropylenes

2006 ◽  
Vol 3-4 ◽  
pp. 363-368 ◽  
Author(s):  
N. Temimi ◽  
Noelle Billon
Keyword(s):  
Strain Rate ◽  
High Speed ◽  
High Strain ◽  
Experimental Studies ◽  
Young Modulus ◽  
Video Camera ◽  
Image Correlation ◽  
Strain Rates ◽  
High Strain Rates ◽  
Low Velocity

Thermo mechanical behaviour of unfilled and filled polypropylenes are studied in tension from 10-4 to 102 s-1. Complementary low velocity compression and shear tests are also performed. A high-speed video camera (up to 2500 frames/s) combined with image analysis, image correlation and an infra red pyrometer allow measuring 3D-strain fields and temperature during tests. Thus, data can be processed without restrictive assumptions. Beside usual (for polymers) temperature and strain rate sensitivities it is found that plastic deformation in these materials does not obey incompressibility assumption. Voiding damage is evidenced in the polymer matrix by SEM observations that result in volume change and significant decrease in Young modulus for both materials. Moreover, an increase in the temperature of more than 10 °C is observed and is likely to modify the behaviour of each material at high strain rates. Shear and compression measurements demonstrate that yield criteria and constitutive equation depend on loading. It is concluded that apparent yield stress in semi-crystalline polypropylene can be a result of a combination of “non strain rate sensitive” “non-cohesive mechanisms” and “strain rate sensitive” “cohesive mechanisms”. Experimental characterisation on polymers should then be revisited as most of the usual assumptions are invalid and non monotonic tests should be generalized.

Mechanical Behavior of Sn1Ag0.5Cu and Sn3Ag0.5Cu Alloys at High Strain Rates

2012 ◽  
Author(s):  
Pradeep Lall ◽  
Sandeep Shantaram ◽  
Jeff Suhling ◽  
David Locker
Keyword(s):  
Strain Rate ◽  
High Speed ◽  
Prolonged Exposure ◽  
High Strain ◽  
Split Hopkinson Pressure Bar ◽  
Image Correlation ◽  
Constitutive Behavior ◽  
Strain Rates ◽  
High Strain Rates ◽  
Test Technique

Electronics may experience high strain rates when subjected to high g-loads of shock and vibration. Material and damage behavior of electronic materials at high strain rates typical of shock and vibration is scarce. Previously studies have shown that second-level interconnects have a high propensity for failure under shock and vibration loads in fine pitch electronics. Exposure to shock and vibration is common in a variety of consumer environments such as automotive and portable electronics. The low strain-rate properties of commonly used SnAgCu solders, including Sn1Ag0.5Cu and Sn3Ag0.5Cu, have been found to evolve with time after prolonged exposure to high temperatures. High strain rate properties of leadfree solder alloys in the strain-rate range of 1–100 sec−1 are scarce. Previous attempts at characterizing the high strain rates properties have focused on the use of the Split Hopkinson Pressure Bar (SHPB), which enables measurements of strain rates in the neighborhood of 1000 per sec. In this paper, a new test-technique developed by the authors has been presented for measurement of material constitutive behavior. The instrument enables attaining strain rates in the neighborhood of 1 to 100 per sec. Tests are conducted at strain rates 10, 35 and 50 per sec. High speed cameras operating at 75,000 fps have been used in conjunction with digital image correlation for the measurement of full-field strain during the test. Constancy of cross-head velocity has been demonstrated during the test from the unloaded state to the specimen failure. Solder alloy constitutive behavior has been measured for SAC105, SAC305 solders. Non-linear Ramberg-Osgood model has been used to fit the material data. The Ramberg-Osgood model available in Abaqus has been used for tensile test simulation and to correlate with DIC based experimental strain data.

scholarly journals Use of simulated experiments for material characterization of brittle materials subjected to high strain rate dynamic tension

2017 ◽  
Vol 375 (2085) ◽  
pp. 20160168 ◽  
Author(s):  
Bratislav Lukić ◽  
Dominique Saletti ◽  
Pascal Forquin
Keyword(s):  
High Speed ◽  
Dynamic Range ◽  
High Strain ◽  
Experimental Testing ◽  
Brittle Materials ◽  
Strain Rates ◽  
High Strain Rates ◽  
Extrinsic Factors ◽  
Full Field ◽  
Ultra High Speed

Rapid progress in ultra-high-speed imaging has allowed material properties to be studied at high strain rates by applying full-field measurements and inverse identification methods. Nevertheless, the sensitivity of these techniques still requires a better understanding, since various extrinsic factors present during an actual experiment make it difficult to separate different sources of errors that can significantly affect the quality of the identified results. This study presents a methodology using simulated experiments to investigate the accuracy of the so-called spalling technique (used to study tensile properties of concrete subjected to high strain rates) by numerically simulating the entire identification process. The experimental technique uses the virtual fields method and the grid method. The methodology consists of reproducing the recording process of an ultra-high-speed camera by generating sequences of synthetically deformed images of a sample surface, which are then analysed using the standard tools. The investigation of the uncertainty of the identified parameters, such as Young's modulus along with the stress–strain constitutive response, is addressed by introducing the most significant user-dependent parameters (i.e. acquisition speed, camera dynamic range, grid sampling, blurring), proving that the used technique can be an effective tool for error investigation. This article is part of the themed issue ‘Experimental testing and modelling of brittle materials at high strain rates’.

Influence of Temperature and Strain Rate on the Mechanical Behaviour of Aluminium Alloy AA6060

2014 ◽  
Vol 794-796 ◽  
pp. 520-525
Author(s):  
Vincent Vilamosa ◽  
Arild H. Clausen ◽  
Odd Sture Hopperstad ◽  
Tore Børvik ◽  
Svein Skjervold
Keyword(s):  
Strain Rate ◽  
High Speed ◽  
High Strain ◽  
True Strain ◽  
Constitutive Models ◽  
Local Deformation ◽  
Minor Effect ◽  
Strain Rates ◽  
High Strain Rates ◽  
A Minor

In an attempt to improve the constitutive models for 6xxx aluminium alloys at high temperatures and high strain rates, a comprehensive test series has been carried out for AA6060. Uniaxial tension tests were performed at various strain rates from 0.01 s-1to 1000 s-1and temperatures from 20 °C to 350 °C. The tests were carried out using a standard tensile machine for low to moderate strain rates and a split-Hopkinson tension bar (SHTB) system for high strain rates. In both cases, an induction apparatus was used to heat the sample while local deformation measurements were obtained with a high-speed camera and used to estimate the true strain beyond necking. Strong coupling between the influence of strain rate and temperature on the stress-strain behaviour was found. At room temperature, the strain rate has a minor effect on the behaviour of AA6060. On the other hand, a significant increase of the yield stress and work-hardening with strain-rate is observed for temperatures above (K), being the melting temperature; i.e., above 673 K.

Approaches to Synchronise Conventional Measurements with Optical Techniques at High Strain Rates

2011 ◽  
Vol 70 ◽  
pp. 75-80 ◽  
Author(s):  
Duncan A. Crump ◽  
Janice M. Dulieu-Barton ◽  
Marco L. Longana
Keyword(s):  
Polymer Composites ◽  
High Speed ◽  
High Strain ◽  
Image Correlation ◽  
Test Machine ◽  
Strain Rates ◽  
High Strain Rates ◽  
Optical Techniques ◽  
Specific Loading ◽  
Military Applications

Polymer composites are increasingly being used in high-end and military applications, mainly due to their excellent tailorability to specific loading scenarios and strength/stiffness to weight ratios. The overall purpose of the research project is to develop an enhanced understanding of the behaviour of fibre reinforced polymer composites when subjected to high velocity loading. This is particularly important in military applications, where composite structures are at a high risk of receiving high strain rate loading, such as those resulting from collisions or blasts. The work described here considers an approach that allows the collection of full-field temperature and strain data to investigate the complex viscoelastic behaviour of composite material at high strain rates. To develop such a data-rich approach digital image correlation (DIC) is used to collect the displacement data and infra-red thermography (IRT) is used to collect temperature data. The use of optical techniques at the sampling rates necessary to capture the behaviour of composites subjected to high loading rates is novel and requires using imaging systems at the far extent of their design specification. One of the major advantages of optical techniques is that they are non-contact; however this also forms one of the challenges to their application to high speed testing. The separate camera systems and the test machine/loading system must be synchronised to ensure that the correct strain/temperature measurement is correlated with the correct temporal value of the loading regime. The loading rate exacerbates the situation where even at high sampling rates the data is discrete and therefore it is difficult to match values. The work described in the paper concentrates on investigating the possibility of the high speed DIC and synchronisation. The limitations of bringing together the techniques are discussed in detail, and a discussion of the relative merits of each synchronisation approach is included, which takes into consideration ease of use, accuracy, repeatability etc.

Dynamic Characteristics of the Sinter-Forged Cu-Cr Alloys with the Variation of Chrome Content

2006 ◽  
Vol 116-117 ◽  
pp. 255-258
Author(s):  
Jung Han Song ◽  
Hoon Huh
Keyword(s):  
Dynamic Response ◽  
Dynamic Characteristics ◽  
High Speed ◽  
High Strain ◽  
Split Hopkinson Pressure Bar ◽  
Testing Machine ◽  
Impact Behavior ◽  
Stress Wave Propagation ◽  
Strain Rates ◽  
High Strain Rates

This paper is concerned with the dynamic characteristics of sinter-forged Cu–Cr alloy for various strain-rates. The amount of the chrome content is varied from 10 %wt to 30 %wt in order to investigate the influence of the chrome content on the dynamic characteristics. The dynamic response at the corresponding level of strain-rate should be obtained with an adequate experimental technique and corresponding apparatus due to the inertia effect and the stress wave propagation. In this paper, the high speed tensile testing machine is utilized in order to identify the dynamic response of the Cu–Cr alloy at the intermediate strain-rates and the split Hopkinson pressure bar is used at the high strain-rates. Experimental results from both the quasi-static and the high strain-rates up to the 5000/s are interpolated with respect to the amount of the chrome content in order to construct the Johnson–Cook and the modified Johnson–Cook model as the constitutive relation for numerical simulation of the dynamic impact behavior of electrodes.

scholarly journals Measurement of fracture properties of concrete at high strain rates

2017 ◽  
Vol 375 (2085) ◽  
pp. 20160174 ◽  
Author(s):  
V. Rey-De-Pedraza ◽  
D. A. Cendón ◽  
V. Sánchez-Gálvez ◽  
F. Gálvez
Keyword(s):  
Tensile Strength ◽  
High Speed ◽  
High Strain ◽  
Experimental Testing ◽  
Direct Analysis ◽  
Strain Rates ◽  
High Strain Rates ◽  
Dynamic Tensile Strength ◽  
Element Analysis ◽  
Initial Work

An analysis of the spalling technique of concrete bars using the modified Hopkinson bar was carried out. A new experimental configuration is proposed adding some variations to previous works. An increased length for concrete specimens was chosen and finite-element analysis was used for designing a conic projectile to obtain a suitable triangular impulse wave. The aim of this initial work is to establish an experimental framework which allows a simple and direct analysis of concrete subjected to high strain rates. The efforts and configuration of these primary tests, as well as the selected geometry and dimensions for the different elements, have been focused to achieve a simple way of identifying the fracture position and so the tensile strength of tested specimens. This dynamic tensile strength can be easily compared with previous values published in literature giving an idea of the accuracy of the method and technique proposed and the possibility to extend it in a near future to obtain other mechanical properties such as the fracture energy. The tests were instrumented with strain gauges, accelerometers and high-speed camera in order to validate the results by different ways. Results of the dynamic tensile strength of the tested concrete are presented. This article is part of the themed issue ‘Experimental testing and modelling of brittle materials at high strain rates’.

Material Behaviors of PBX Simulant with Various Strain Rates

2013 ◽  
Vol 535-536 ◽  
pp. 117-120 ◽  
Author(s):  
Chung Hee Park ◽  
Seh Wan Jeong ◽  
Hoon Huh ◽  
Jung Su Park
Keyword(s):  
Strain Hardening ◽  
High Speed ◽  
High Strain ◽  
Split Hopkinson Pressure Bar ◽  
Testing Machine ◽  
Materials Testing ◽  
Strain Rates ◽  
High Strain Rates ◽  
Material Behaviors ◽  
Compressive Tests

This paper is concerned with the material behaviors of PBX(Polymer Bonded eXplosive) simulant at various strain rates ranging from 0.0001/sec to 3150/sec. Material behaviors of PBX at the high strain rates are important in the prediction of deformation modes of PBX in a warhead which undergoes severe impact loading. Inert PBX stimulant which has analogous material behaviors with PBX was utilized for material tests due to safety issues. Uniaxial compressive tests at quasi-static and intermediate strain rates were conducted with cylindrical specimen using a dynamic materials testing machine, INSTRON 8801. Uniaxial compressive tests at high strain rates ranging from 1200/sec to 3150/sec were conducted using a split Hopkinson pressure bar. Deformation behaviors were investigated using captured images obtained from a high-speed camera. The strain hardening behaviors of PBX simulant were formulated by proposed strain rate-dependent strain hardening model.

scholarly journals Measurement of the Deformation of Aluminum Alloys under High Strain Rates Using High Speed Digital Cameras

2013 ◽  
Vol 03 (02) ◽  
pp. 112-121 ◽  
Author(s):  
Gbadebo Owolabi ◽  
Daniel Odoh ◽  
Alex Peterson ◽  
Akindele Odeshi ◽  
Horace Whitworth
Keyword(s):  
Aluminum Alloys ◽  
High Speed ◽  
High Strain ◽  
Strain Rates ◽  
Digital Cameras ◽  
High Strain Rates
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