scholarly journals A homogenization method for ductile-brittle composite laminates at large deformations

2017 ◽  
Vol 113 (5) ◽  
pp. 814-833 ◽  
Author(s):  
Konstantinos Poulios ◽  
Christian F. Niordson
Keyword(s):  
Composite Laminates ◽  
Large Deformations ◽  
Homogenization Method ◽  
Brittle Composite

Prediction of progressive damage and strength of IM7/977-3 composites using the Eigendeformation-based homogenization approach: Static loading

2016 ◽  
Vol 51 (10) ◽  
pp. 1455-1472 ◽  
Author(s):  
Michael J Bogdanor ◽  
Caglar Oskay
Keyword(s):  
Ultimate Strength ◽  
Composite Laminates ◽  
Mechanical Response ◽  
Multiscale Model ◽  
Homogenization Method ◽  
Average Error ◽  
Average Prediction Error ◽  
Homogenization Approach ◽  
Open Hole ◽  
Tension And Compression

This paper presents the results from the authors’ participation in the Air Force Research Laboratory’s Damage Tolerance Design Principles Program. The Eigendeformation-based reduced order homogenization method was employed to predict the mechanical response of a suite of open hole and unnotched IM7/977-3 composite laminates under static tension and compression. Damage accumulation, effective stiffness, and ultimate strength blind predictions are included in addition to the results of the recalibration study. In blind predictions, the proposed multiscale model produced predictions with an average error of 13.1% compared to the experiments for static ultimate strength and 13.6% for stiffness. After recalibration, the average prediction error was improved to 8.7% for static ultimate strength and 4.4% for stiffness. Details of the blind predictions and the recalibration are discussed.

scholarly journals Homogenization of fully nonlinear rod lattice structures: on the size of the RVE and micro structural instabilities

2021 ◽  
Author(s):  
Ludwig Herrnböck ◽  
Paul Steinmann
Keyword(s):  
Large Deformations ◽  
Mechanical Response ◽  
Three Dimensional ◽  
Homogenization Method ◽  
Volume Element ◽  
Lattice Structures ◽  
Micro Scale ◽  
Macro Scale ◽  
Unit Cells ◽  
Structural Instabilities

AbstractThis work investigates the possibility of applying two-scale computational homogenization to rod lattice structures emerging, for instance, from additive manufacturing. The influence of the number of unit cells within the representative volume element (RVE), thus, the RVE’s size on the homogenized mechanical response is studied for occurring microscopic structural instabilities. Therein, the macro-scale, described in terms of three-dimensional continuum mechanics, is coupled to the micro-scale described by geometrically exact rods, enabling arbitrary large deformations and rotations. A special feature of the presented framework is that the rods building the lattice structures are not restricted to deform purely elastically but may deform inelastically. The mechanical response of lattice structures is investigated by applying the developed homogenization method to an exemplary lattice. Under special loads the structure reaches an instable state and may buckle. The appearance of instabilities depends on the geometric properties of the lattice’s underlying rods and the RVE’s size.

scholarly journals Modeling and optimization of bistable composite laminates for piezoelectric actuation

2011 ◽  
Vol 22 (18) ◽  
pp. 2181-2191 ◽  
Author(s):  
David N. Betts ◽  
H. Alicia Kim ◽  
Christopher R. Bowen
Keyword(s):  
Composite Laminates ◽  
Shape Control ◽  
Large Deformations ◽  
Aerospace Industry ◽  
Actuation Voltage ◽  
Piezoelectric Actuation ◽  
Potential Mechanism ◽  
Optimization Study ◽  
Piezoelectric Layers ◽  
Load Carrying

Adaptive structures that allow large deformations under the application of a low and noncontinuous energy input are gaining increasing interest in the aerospace industry. One potential mechanism of realizing shape control is piezoelectric actuation of asymmetric composite laminates. This article presents an optimization study for the design of bistable laminates for a reversible snap-through enabled by two orthogonal piezoelectric layers. The formulation optimizes the load-carrying capability of the structure subject to deflection and actuation limits through a variation in ply orientations and laminate geometry. We find the problem to be multimodal with the multiple optima to be dependent on the loading and snap-through directions and the complex constraint boundary interactions. A reduction in the total actuation voltage is achieved through the simultaneous use of the positive and negative working ranges of the two piezoelectric layers.

scholarly journals A general, implicit, finite-strain FE$$^2$$ framework for the simulation of dynamic problems on two scales

2021 ◽  
Author(s):  
Erik Tamsen ◽  
Daniel Balzani
Keyword(s):  
Finite Strain ◽  
Large Deformations ◽  
Homogenization Method ◽  
Finite Element Program ◽  
Tangent Moduli ◽  
Engineering Problems ◽  
Strain Formulation ◽  
Element Program ◽  
Split Hopkinson ◽  
Fully Coupled

AbstractIn this paper we present a fully-coupled, two-scale homogenization method for dynamic loading in the spirit of FE$$^2$$ 2 methods. The framework considers the balance of linear momentum including inertia at the microscale to capture possible dynamic effects arising from micro heterogeneities. A finite-strain formulation is adapted to account for geometrical nonlinearities enabling the study of e.g. plasticity or fiber pullout, which may be associated with large deformations. A consistent kinematic scale link is established as displacement constraint on the whole representative volume element. The consistent macroscopic material tangent moduli are derived including micro inertia in closed form. These can easily be calculated with a loop over all microscopic finite elements, only applying existing assembly and solving procedures. Thus, making it suitable for standard finite element program architectures. Numerical examples of a layered periodic material are presented and compared to direct numerical simulations to demonstrate the capability of the proposed framework. In addition, a simulation of a split Hopkinson tension test showcases the applicability of the framework to engineering problems.

Reliable Bonding of Composite Laminates Using Reflowable Epoxy Resins

2019 ◽  
Author(s):  
Frank Palmieri ◽  
Tyler Hudson ◽  
Roberto Cano ◽  
Erik Tastepe ◽  
Dean Rufeisen ◽  
...  
Keyword(s):  
Composite Laminates ◽  
Epoxy Resins
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