scholarly journals Novel Methodology for Experimental Characterization of Micro-Sandwich Materials

Materials ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4396
Author(s):  
Samuel Hammarberg ◽  
Jörgen Kajberg ◽  
Simon Larsson ◽  
Ramin Moshfegh ◽  
Pär Jonsén
Keyword(s):  
Automotive Industry ◽  
Numerical Models ◽  
Constitutive Models ◽  
High Strength ◽  
Image Correlation ◽  
Displacement Fields ◽  
Plane Shear ◽  
Cold Forming ◽  
Out Of Plane ◽  
Sandwich Materials

Lightweight components are in demand from the automotive industry, due to legislation regulating greenhouse gas emissions, e.g., CO2. Traditionally, lightweighting has been done by replacing mild steels with ultra-high strength steel. The development of micro-sandwich materials has received increasing attention due to their formability and potential for replacing steel sheets in automotive bodies. A fundamental requirement for micro-sandwich materials to gain significant market share within the automotive industry is the possibility to simulate manufacturing of components, e.g., cold forming. Thus, reliable methods for characterizing the mechanical properties of the micro-sandwich materials, and in particular their cores, are necessary. In the present work, a novel method for obtaining the out-of-plane properties of micro-sandwich cores is presented. In particular, the out-of-plane properties, i.e., transverse tension/compression and out-of-plane shear are characterized. Test tools are designed and developed for subjecting micro-sandwich specimens to the desired loading conditions and digital image correlation is used to qualitatively analyze displacement fields and fracture of the core. A variation of the response from the material tests is observed, analyzed using statistical methods, i.e., the Weibull distribution. It is found that the suggested method produces reliable and repeatable results, providing a better understanding of micro-sandwich materials. The results produced in the present work may be used as input data for constitutive models, but also for validation of numerical models.

Nonlinear Analysis of Steel Reinforced High Strength and High Performance Concrete Eccentric Columns

2010 ◽  
Vol 450 ◽  
pp. 223-226 ◽  
Author(s):  
Shan Suo Zheng ◽  
Wei Wang ◽  
Bin Wang ◽  
Lei Li ◽  
Yi Hu
Keyword(s):  
High Performance ◽  
High Performance Concrete ◽  
Numerical Models ◽  
Constitutive Models ◽  
High Strength ◽  
Failure Criteria ◽  
Experimental Results ◽  
Finite Element Program ◽  
Calculation Results ◽  
Element Program

According to experiment of four steel reinforced high strength and high performance concrete(SRHSHPC) columns with different eccentricity, this paper establishes four equally parameter numerical models by finite element program ANSYS. The failure mechanism, failure mode and mechanical behaviors of the SRHSHPC columns with large and small eccentricity can be revealed by comparing the numerical simulation results with the corresponding experimental results. And the approximate plane-section assumption in SRHSHPC eccentric columns is verified by the study of the relationship between load and strain. It is shown that when constitutive models and failure criteria of SRHSHPC and steel are in precise case, the calculation results agree well with the corresponding experimental results.

An Improved Digital Image Correlation Method Applied to Scanning Probe Microscope Images

2009 ◽  
Author(s):  
Wei Chu ◽  
Joseph Fu ◽  
Theodore Vorburger
Keyword(s):  
Digital Image Correlation ◽  
Digital Image ◽  
Correlation Method ◽  
Image Correlation ◽  
Scanning Probe ◽  
Real Surface ◽  
Displacement Fields ◽  
Nonlinearity Error ◽  
Direction Error ◽  
Out Of Plane

Digital image correlation (DIC) is a method for measuring the surface displacements and displacement gradients in materials under deformation. The method has also been applied to the calculation of image distortion for scanning probe microscopy (SPM). The traditional DIC method directly uses the intensity values of compared images but does not take out-of-plane nonlinearity error into account. However, in SPM measurements, the recorded z-direction value is a sum of the real surface height of the sample and any longitudinal deformation of the piezoelectric tube. In order to improve the calculation accuracy of the displacement fields, an improved DIC method is performed here. Two new parameters related to out-of-plane error are introduced in the mathematical modeling. The in-plane displacements between two compared images are then calculated pixel by pixel, with the z-direction error accounted for. This method is tested by applying it to two pairs of atomic force microscopy (AFM) images along the fast and slow scan directions.

scholarly journals Strain distribution during air bending of ultra-high strength steels

2021 ◽  
Author(s):  
Aki-Petteri Pokka ◽  
Anna-Maija Arola ◽  
Antti Kaijalainen ◽  
Vili Kesti ◽  
Jari Larkiola
Keyword(s):  
Surface Defects ◽  
Numerical Models ◽  
Measurement Data ◽  
High Strength Steels ◽  
High Strength ◽  
Image Correlation ◽  
Bending Tests ◽  
Air Bending ◽  
Bending Process ◽  
Ultra High Strength Steels

Air bending is a widely used method for forming ultra-high strength steels (UHSS). However, the limited formability of UHSS poses some challenges for the bending process in the form of strain localisation, surface defects, punch detachment (multi-breakage) and pseudo-polygonal “nut-like” shape of the bend. In this study, the bendability of three UHSS grades (700, 900 and 1100 MPa) is investigated with 3-point bending tests, utilising Digital Image Correlation (DIC) for measuring the strain distributions on the outer curvature. The differences in the extent of multi-breakage and the bend shapes are also studied, and these observations are correlated with the findings from the bending force and strain measurements. The differences between the investigated UHSS grades are significant. The 900 MPa grade produces more localised strain distributions and pronounced multi-breakage compared to the other grades, along with a more polygonal “nut-like” geometry. The reasons and effects of the multi-breakage phenomenon, as well as the causes for the observed differences in the behaviour of the materials are discussed in this paper. The presented results and the measurement data provide more information about the behaviour of the investigated materials in bending, and can be used for improving bending simulation, numerical models, and workshop instructions.

scholarly journals Experimental investigation of the failure modes of in-plane loaded inserts in CFRP sandwich panels

2018 ◽  
Vol 188 ◽  
pp. 04025
Author(s):  
Philip Richert ◽  
Athanasios Dafnis ◽  
Kai-Uwe Schröder
Keyword(s):  
Experimental Investigation ◽  
Digital Image Correlation ◽  
Digital Image ◽  
Failure Modes ◽  
Image Correlation ◽  
Honeycomb Core ◽  
Out Of Plane ◽  
Aluminum Honeycomb ◽  
Correlation System ◽  
Sandwich Materials

The aim of this paper is the experimental determination and investigation of the different failure modes of various insert types under inplane load in sandwich materials with CFRP face sheets and a perforated aluminum honeycomb core. In addition, also insert under an out-of-plane load are tested. In total three different kind of inserts are investigated: blind inserts, trough-the-thickness inserts and special inserts which are developed within the iBOSS research project. The inserts are tested until failure and monitored with the digital image correlation system Aramis. This test monitoring is intended to determine the first failure mode. It is shown that this works well for out-of-plane loaded insert connections and the special inserts under in-plane load. However, this does not work so well with in-plane loaded standard inserts. In further investigations, a failure of the adhesive shortly before failure of the top layers can be shown.

Nonlinear Properties of High Strength Paperboards

1999 ◽  
Vol 121 (3) ◽  
pp. 272-277 ◽  
Author(s):  
Y. P. Qiu ◽  
M. Millan ◽  
C. H. Lin ◽  
T. D. Gerhardt
Keyword(s):  
Material Properties ◽  
Solid Mechanics ◽  
High Strength ◽  
Nonlinear Material ◽  
Limited Data ◽  
Plane Shear ◽  
Nonlinear Properties ◽  
Out Of Plane ◽  
Poisson's Ratios ◽  
Poisson’S Ratios

Paper is a highly anisotropic and nonlinear material. Solid mechanics research on paper structures has been hampered by limited data on the nonlinear material properties of paperboards. In particular, it has been difficult to measure shear and z-directional properties. In this paper, nonlinear material response of paper laminates under simple loading conditions (uniaxial compression in three directions and in plane shear) are presented. Also, data is presented for various Poisson’s ratios. It was found that paper behaves differently along the thickness direction than along the in-plane directions. Poisson’s ratios are usually nonlinear with large deformation. In-plane Poisson’s ratios decrease, while out-of-plane Poisson’s ratios increase with the applied load.

Global-Local Characterization and Numerical Modeling of TWB Laser Welded Joints

2017 ◽  
Author(s):  
F. Nalli ◽  
P. Russo Spena ◽  
L. Cortese ◽  
D. Reiterer
Keyword(s):  
Local Level ◽  
High Strength Steels ◽  
High Strength ◽  
Image Correlation ◽  
Correlation Technique ◽  
Fe Model ◽  
Base Metals ◽  
Displacement Fields ◽  
Advanced High Strength Steels ◽  
Tailor Welded Blanks

Sheet forming of tailor welded blanks (TWBs) of advanced high strength steels is complex because of the notable differences in mechanical properties, and hence in formability, of base metals, heat affected zones and weld seam. In this work, an accurate characterization of the mechanical behavior of these regions in TWBs made of a DP and TRIP steel was carried out. Micro-samples, machined from base metals and fusion zone were employed to retrieve the local constitutive laws up to fracture. At the same time, macro-samples, extracted throughout the welded joint were tested to assess the weldment overall behavior. Along with global load-displacement data, strain and displacement fields of the joint were evaluated, using a Digital Image Correlation technique. An FE simulation of the entire joint was setup, using the previously identified material properties. In a comparison between the FE model and experiments, good results were obtained both at a global and local level, up to fracture.

Microstructure of an extruded rapidly solidified Al-8Fe-2Mo alloy

1986 ◽  
Vol 44 ◽  
pp. 548-549
Author(s):  
W. T. Donlon ◽  
J. E. Allison ◽  
S. Shinozaki
Keyword(s):  
Electron Microscopy ◽  
Automotive Industry ◽  
Fuel Economy ◽  
High Strength ◽  
Al Alloys ◽  
Light Weight ◽  
Thin Sections ◽  
Strength And Durability ◽  
Rapidly Solidified ◽  
Whitney Aircraft

Light weight materials which possess high strength and durability are being utilized by the automotive industry to increase fuel economy. Rapidly solidified (RS) Al alloys are currently being extensively studied for this purpose. In this investigation the microstructure of an extruded Al-8Fe-2Mo alloy, produced by Pratt & Whitney Aircraft, Goverment Products Div. was examined in a JE0L 2000FX AEM. Both electropolished thin sections, and extraction replicas were examined to characterize this material. The consolidation procedure for producing this material included a 9:1 extrusion at 340°C followed by a 16:1 extrusion at 400°C, utilizing RS powders which have also been characterized utilizing electron microscopy.

Sign in / Sign up

Export Citation Format

Share Document