Stress distribution in a strip fabricated from a composite material with small-scale curved structure

1996 ◽  
Vol 32 (9) ◽  
pp. 684-690 ◽  
Author(s):  
S. D. Akbarov ◽  
N. Yahnioglu
Keyword(s):  
Composite Material ◽  
Stress Distribution ◽  
Small Scale ◽  
Curved Structure

Fiber-Reinforced Plastics with Locally Adapted Stiffness for Bio-Inspired Hingeless, Deployable Architectural Systems

2017 ◽  
Vol 742 ◽  
pp. 689-696 ◽  
Author(s):  
Larissa Born ◽  
Axel Körner ◽  
Gundula Schieber ◽  
Anna S. Westermeier ◽  
Simon Poppinga ◽  
...  
Keyword(s):  
Composite Material ◽  
Role Models ◽  
Design Principles ◽  
Biological Role ◽  
Small Scale ◽  
Fiber Reinforced ◽  
Reinforced Plastics ◽  
Fiber Reinforced Plastics

This paper presents results of the investigation of two biological role models, the shield bug (Graphosomaitalicum) and the carnivorous Waterwheel plant (Aldrovandavesiculosa). The aim was to identify biological construction and movement principles as inspiration for technical, deployable systems. The subsequent processes of abstraction and simulation of the movement and the design principles are summarized, followed by results on the mechanical investigations on various combinations of fibers and matrices with regard to taking advantage of the anisotropy of fiber-reinforced plastics (FRPs). With the results gained, it was possible to implement defined flexible bending zones in stiff composite components using one composite material, and thereby to mimic the biological role models. First small-scale demonstrators for adaptive façade shading systems – Flectofold and Flexagon – are proving the functionality.

Prediction of Creep Crack Initiation Under Transient Stress Conditions

2006 ◽  
Author(s):  
Catrin M. Davies ◽  
Noel P. O’Dowd ◽  
Kamran M. Nikbin ◽  
George A. Webster
Keyword(s):  
Steady State ◽  
Stress Distribution ◽  
Crack Initiation ◽  
Creep Strain ◽  
Crack Tip ◽  
Steady State Creep ◽  
Creep Model ◽  
Small Scale ◽  
Creep Crack ◽  
Initial Loading

A method to predict the time for creep crack initiation (CCI) from a stationary crack tip is presented. The method is relevant to situations where small scale yield or widespread plasticity conditions prevail on initial loading. Initiation is considered to occur at the attainment of a critical creep strain at a small distance from the crack tip. The model proposed here considers the integrated effects of creep strain accumulation as the stress distribution changes from that on initial loading (controlled by J) to the steady state creep stress distribution (controlled by C*). Material properties are chosen to represent Type 316H stainless steel at 550°C and plane strain conditions are considered. For the conditions examined, the CCI times predicted are significantly shorter times than those predicted using a steady state creep model.

Crack Propagation in a Strain-Crystallizing Elastomer

1962 ◽  
Vol 35 (1) ◽  
pp. 210-223 ◽  
Author(s):  
E. H. Andrews
Keyword(s):  
Stress Distribution ◽  
Crack Propagation ◽  
Natural Rubber ◽  
Crack Growth ◽  
Cyclic Deformation ◽  
Maximum Stress ◽  
Applied Strain ◽  
Small Scale ◽  
Mechanical Hysteresis ◽  
Axis Of Symmetry

Abstract The dependence of small-scale crack propagation in a strain-crystallizing elastomer (natural rubber) upon the applied strain has been studied under conditions of cyclic deformation over a range of frequencies. During each cycle the crack propagates along a well-defined path, different from the axis of symmetry, which is identified as the locus of maximum stress in a stationary stress distribution (i.e., one which does not move with small advances of the crack). The stationary stress hypothesis also accounts for the quantitative dependence of crack growth upon the external constraint. It is shown that a stationary stress distribution could arise as a result of the severe mechanical hysteresis displayed by strain-crystallizing rubbers.

Steady State Crack Growth in Shape Memory Alloys

2013 ◽  
Author(s):  
Selcuk Hazar ◽  
Wael Zaki ◽  
Ziad Moumni ◽  
Gunay Anlas
Keyword(s):  
Steady State ◽  
Stress Distribution ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Crack Growth ◽  
Crack Tip ◽  
Reverse Transformation ◽  
Small Scale ◽  
Local Algorithms ◽  
Non Local

Shape memory alloys experience phase transformation from austenite to martensite around crack tip. When the crack advances, martensitic transformation occurs at the tip and the energy that goes into transformation results in stable crack growth like in the case of plastic deformation. In literature, there are studies on steady-state crack growth in elasto-plastic materials with small scale yielding around crack tip that use stationary movement methods similar to non-local algorithms. In this work, Mode I steady-state crack growth in an edge cracked Nitinol plate is modeled using a non-local stationary movement method. The Zaki-Moumni (ZM) constitutive model is utilized for this purpose. The model is implemented in ABAQUS by means of a user-defined material subroutine (UMAT) to determine transformation zones around the crack tip. Steady-state crack growth is first simulated without considering reverse transformation to calculate the effect of transformation on stress distribution in the wake region, then reverse transformation is taken into account. Stress distribution and transformation regions calculated for both cases are compared to results obtained for the case of a static crack.

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