scholarly journals An Improved Lagrangian-Inverse Method for Evaluating the Dynamic Constitutive Parameters of Concrete

Materials ◽  
2020 ◽  
Vol 13 (8) ◽  
pp. 1871
Author(s):  
Xinlu Yu ◽  
Yingqian Fu ◽  
Xinlong Dong ◽  
Fenghua Zhou ◽  
Jianguo Ning
Keyword(s):  
High Speed ◽  
Inverse Method ◽  
Image Correlation ◽  
Analysis Method ◽  
Stress Strain ◽  
Optical Techniques ◽  
Element Simulation ◽  
Non Linear ◽  
Constitutive Parameters ◽  
Inverse Analysis Method

The dynamic constitutive behaviors of concrete-like materials are of vital importance for structure designing under impact loading conditions. This study proposes a new method to evaluate the constitutive behaviors of ordinary concrete at high strain rates. The proposed method combines the Lagrangian-inverse analysis method with optical techniques (ultra-high-speed camera and digital image correlation techniques). The proposed method is validated against finite-element simulation. Spalling tests were conducted on concretes where optical techniques were employed to obtain the high-frequency spatial and temporal displacement data. We then obtained stress–strain curves of concrete by applying the proposed method on the results of spalling tests. The results show non-linear constitutive behaviors in these stress–strain curves. These non-linear constitutive behaviors can be possibly explained by local heterogeneity of concrete. The proposed method provides an alternative mean to access the dynamic constitutive behaviors which can help future structure designing of concrete-like materials.

A full-range stress-strain model for metallic materials depicting non-linear strain-hardening behavior

2020 ◽  
pp. 030932472095779
Author(s):  
Digendranath Swain ◽  
S Karthigai Selvan ◽  
Binu P Thomas ◽  
Ahmedul K Asraff ◽  
Jeby Philip
Keyword(s):  
Constitutive Model ◽  
Strain Hardening ◽  
Image Correlation ◽  
Linear Strain ◽  
Stress Strain ◽  
Material Parameters ◽  
Hardening Behavior ◽  
Non Linear ◽  
Strain Hardening Behavior ◽  
Strain Model

Ramberg-Osgood (R-O) type stress-strain models are commonly employed during elasto-plastic analysis of metals. Recently, 2-stage and 3-stage R-O variant models have been proposed to replicate stress-strain behavior under large plastic deformation. The complexity of these models increases with the addition of each stage. Moreover, these models have considered deformation till necking only. In this paper, a simplistic multi-stage constitutive model is proposed to capture the strain-hardening non-linearity shown by metals including its post necking behavior. The constitutive parameters of the proposed stress-strain model can be determined using only elastic modulus and yield strength. 3-D digital image correlation was used as an experimental tool for measuring full-field strains on the specimens, which were subsequently utilized to obtain the material parameters. Our constitutive model is demonstrated with an aerospace-grade stainless steel AISI 321 wherein deformation response averaged over the gauge length (GL) and at a local necking zone are compared. The resulting averaged and local material parameters obtained from the proposed model provide interesting insights into the pre and post necking deformation behavior. Our constitutive model would be useful for characterizing highly ductile metals which may or may not depict non-linear strain hardening behavior including their post necking deformations.

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.

The Experimental Modal Analysis of High Speed Machining Tool System Based on Integral Polynomial Recognition Method

2012 ◽  
Vol 723 ◽  
pp. 159-163 ◽  
Author(s):  
Fei Xiao ◽  
Xian Li Liu ◽  
Yan Xin Wang ◽  
Li Jia Liu ◽  
Da Qu
Keyword(s):  
Modal Analysis ◽  
High Speed ◽  
Simulation Method ◽  
Experimental Modal Analysis ◽  
Modal Parameters ◽  
High Speed Machining ◽  
Analysis Method ◽  
Recognition Method ◽  
Element Simulation ◽  
Integral Polynomial

According to the principle of the experimental modal analysis, this study is based on tool system of the MIKRON UCP 710 numerical control machining center as test object for experimental modal analysis. Using the integral polynomial recognition method to identify the modal parameters (natural frequency, structural damping, and modal shape), and finally matching the results with the vector analysis method and the finite element simulation method. The results show that integral polynomial recognition method has higher precision than the vector analysis method to identify the multi-degree of freedom system; the experimental modal analysis can also obtain better modal parameters of the structure system, and a higher precision than the finite element simulation method. Obtained the MIKRON UCP 710 high-speed milling center tool system accurate modal parameters provides the necessary theoretical and experimental basis for the further study of the stability properties in the cutting processing of the high speed machining tool system.

Finite Element Analysis of Slider in High-Speed Horizontal NC Center

2011 ◽  
Vol 225-226 ◽  
pp. 43-46 ◽  
Author(s):  
Ming Cong ◽  
Tao Han ◽  
Qiang Zhao ◽  
Tie Jun Lan ◽  
Xiu Yong Ju
Keyword(s):  
Boundary Condition ◽  
Finite Element ◽  
High Speed ◽  
Simulation Analysis ◽  
The Other ◽  
Analysis Method ◽  
Great Role ◽  
Original Design ◽  
Element Analysis ◽  
Element Simulation

Slider is one of the most important parts in High-Speed Horizontal Machining NC center, it plays a great role in the performance of static and dynamic. In order to assure the working accuracy and dynamic characters, slider must be analyzed to verify the reasonable of original design. According to the structure of slider and based on the theoretical and finite element simulation analysis method, a more reasonable boundary condition is carried out. To be noted that in this paper a method using the conception of combination is introduced. On the other hand the counterforce can be more accurate than before and it makes the following analysis easier.

Validation of Impact Simulations of a Car Bonnet by Full-Field Optical Measurements

2011 ◽  
Vol 70 ◽  
pp. 57-62
Author(s):  
George Lampeas ◽  
Vasilis Pasialis ◽  
Thorsten Siebert ◽  
Mara Feligiotti ◽  
Andrea Pipino
Keyword(s):  
Displacement Field ◽  
High Speed ◽  
Mechanical Response ◽  
Three Dimensional ◽  
Quantitative Information ◽  
Image Correlation ◽  
Optical Measurements ◽  
Optical Techniques ◽  
Full Field ◽  
Dynamic Events

Innovative designs of transport vehicles need to be validated in order to demonstrate reliability and provide confidence. The most common approaches to such designs involve simulations based on Finite Element (FE) analysis, used to study the mechanical response of the structural elements during critical events. These simulations need reliable validation techniques, especially if anisotropic materials, such as fibre reinforced polymers, or complex designs, such as automotive components are considered. It is normal practice to assess the accuracy of numerical results by comparing the predicted values to corresponding experimental data. In this frame, the use of whole field optical techniques has been proven successful in the validation of deformation, strain, or vibration modes [1]. The strength of full-field optical techniques is that the whole displacement field can be visualized and analyzed. By using High Speed cameras, the Digital Image Correlation (DIC) method can be applied to highly non-linear dynamic events and deliver quantitative information about the three-dimensional displacement field [2].

Experimental Measurement of In-Plane Rolling Nonpneumatic Tire Vibrations Using High-Speed Imaging

2019 ◽  
Vol 47 (3) ◽  
pp. 196-210
Author(s):  
Meghashyam Panyam ◽  
Beshah Ayalew ◽  
Timothy Rhyne ◽  
Steve Cron ◽  
John Adcox
Keyword(s):  
High Speed ◽  
Image Correlation ◽  
Dynamic Mode Decomposition ◽  
Dynamic Mode ◽  
High Speed Imaging ◽  
Correlation Algorithm ◽  
Mode Decomposition ◽  
Series Of Experiments ◽  
Plane Deformations ◽  
Dominant Frequencies

ABSTRACT This article presents a novel experimental technique for measuring in-plane deformations and vibration modes of a rotating nonpneumatic tire subjected to obstacle impacts. The tire was mounted on a modified quarter-car test rig, which was built around one of the drums of a 500-horse power chassis dynamometer at Clemson University's International Center for Automotive Research. A series of experiments were conducted using a high-speed camera to capture the event of the rotating tire coming into contact with a cleat attached to the surface of the drum. The resulting video was processed using a two-dimensional digital image correlation algorithm to obtain in-plane radial and tangential deformation fields of the tire. The dynamic mode decomposition algorithm was implemented on the deformation fields to extract the dominant frequencies that were excited in the tire upon contact with the cleat. It was observed that the deformations and the modal frequencies estimated using this method were within a reasonable range of expected values. In general, the results indicate that the method used in this study can be a useful tool in measuring in-plane deformations of rolling tires without the need for additional sensors and wiring.

scholarly journals Full-Field Operational Modal Analysis of an Aircraft Composite Panel from the Dynamic Response in Multi-Impact Test

Sensors ◽  
2021 ◽  
Vol 21 (5) ◽  
pp. 1602
Author(s):  
Ángel Molina-Viedma ◽  
Elías López-Alba ◽  
Luis Felipe-Sesé ◽  
Francisco Díaz
Keyword(s):  
Modal Analysis ◽  
Energy Absorption ◽  
High Speed ◽  
Operational Modal Analysis ◽  
Modal Identification ◽  
Image Correlation ◽  
Composite Panel ◽  
Impact Excitation ◽  
Full Field ◽  
The Impact

Experimental characterization and validation of skin components in aircraft entails multiple evaluations (structural, aerodynamic, acoustic, etc.) and expensive campaigns. They require different rigs and equipment to perform the necessary tests. Two of the main dynamic characterizations include the energy absorption under impact forcing and the identification of modal parameters through the vibration response under any broadband excitation, which also includes impacts. This work exploits the response of a stiffened aircraft composite panel submitted to a multi-impact excitation, which is intended for impact and energy absorption analysis. Based on the high stiffness of composite materials, the study worked under the assumption that the global response to the multi-impact excitation is linear with small strains, neglecting the nonlinear behavior produced by local damage generation. Then, modal identification could be performed. The vibration after the impact was measured by high-speed 3D digital image correlation and employed for full-field operational modal analysis. Multiple modes were characterized in a wide spectrum, exploiting the advantages of the full-field noninvasive techniques. These results described a consistent modal behavior of the panel along with good indicators of mode separation given by the auto modal assurance criterion (Auto-MAC). Hence, it illustrates the possibility of performing these dynamic characterizations in a single test, offering additional information while reducing time and investment during the validation of these structures.

Sign in / Sign up

Export Citation Format

Share Document