Effects of Structure and Property Variations Within Hierarchal Biomineralized Composites Using Finite Element Methods

2016 ◽  
Author(s):  
Matt Nelms ◽  
Ken Livi ◽  
Bryan Crawford ◽  
A. M. Rajendran ◽  
Wayne Hodo
Keyword(s):  
Finite Element ◽  
High Strength ◽  
Elastic Response ◽  
Science And Engineering ◽  
Structure And Property ◽  
Alligator Gar ◽  
Flaw Tolerance ◽  
Delamination Resistance ◽  
Abalone Shell ◽  
Atractosteus Spatula

Biological materials (biomaterials) have had a marked increase in interest from the material science and engineering community due to unique characteristics and properties that are typically sought after in traditional engineering materials. During the last few decades, research on biomineralized composites such as abalone shell, fish armor, turtle shell, and human bone revealed that those biological systems possess a carefully arranged multilayered composite structure. Unlike metals, ceramics, and traditional composite materials; biomineralized composites often possess enhanced characteristics such as, penetration resistance high toughness, flaw tolerance energy dissipation, damage mitigation, and delamination resistance all while achieving high strength-to-weight ratios. In this research experimentally driven finite element modeling was used to investigate the elastic response for the biocomposite structure. The Atractosteus spatula (Alligator gar) was used as the model structure for determining the elastic properties.

Multiscale Experimental Characterization of the Delamination Resistant Mechanisms Found in the Biomineralized Exoskeleton Fish Scale Composite

2016 ◽  
Author(s):  
Wayne Hodo ◽  
Matt Nelms ◽  
Bryan Crawford ◽  
Kenneth Livi ◽  
A. M. “Raj” Rajendran
Keyword(s):  
Elastic Moduli ◽  
High Strength ◽  
Soft Materials ◽  
Layered Composite ◽  
Layered System ◽  
Fish Scale ◽  
Inhomogeneous Materials ◽  
Alligator Gar ◽  
Multilayered Systems ◽  
Delamination Resistance

Engineered man-made composite (inhomogeneous) materials are well known for their superior structural properties. Man-made composite materials and multilayered systems are widely used in civilian and military applications. The combined multilayered systems are attractive because they have the characteristics of being energy absorbent, lightweight, high-strength, high-stiffness, and can provide good fatigue and corrosion resistance. Although the engineered composites are promising and offer mutual exclusive material properties that are not found in other structural materials, they are prone to delamination at the glued layered interface. In contrast to man-made composites, most superior performing materials found in nature possess a hierarchal biomineralized composite structure that tends to be delamination resistant. These delaminate resistant biocomposite structures [e.g. alligator gar’s (Atractosteus Spatula) exoskeleton fish scale] have mechanical properties that vastly exceed the properties of their relatively weak constituents. The fish scale is made up of 90 percent hard (inorganic minerals) and 10 percent soft (polymer-like organic collagen fibers) by volume. Nature integrates hard and soft materials at different length scales to form a two-layered composite that better resists delamination. The objective of this research was to use scanning electron microscopy (SEM) and nanoindentation to investigate the delamination resistant behavior occurring at the layered interface for the alligator gar fish scale composite. The SEM imagery showed at the micron level the collagen bundles + B-Ap crystals (C/B-Ap) form a distinctive two-layered system that is connected by what is described as sawtooth geometrically structured interface. The outermost layer for the exoskeleton fish scale is called ganoine while the inner layer called bone. The layers interface seems to be mainly bonded by mechanical means using sawtooth notches, rather than the chemicals adhesives used in the man-made laminated planar interfaced composites. The notched regions for ganoine+bone materials overlap and are embedded at various depths within each layer to form periodic “repeating” bonded connections. The indentation measurements taken at the nano-level showed that elastic moduli have property gradients occurring through the interfacial transition zone. Noticeably the ganoine layer has elastic moduli ranging from [98–67] GPa while the bone layer elastic moduli ranged from [20–13] GPa. The research findings indicate the sawtooth connections perhaps provide enhanced shear resistance at the interface and may help inhibit debonding. Additionally, the notched interlocking provides a less discrete (graded) interface, which seems to promote durability and delamination resistance.

Composite Solutions for Deck Catamarans

2018 ◽  
Vol 55 (1) ◽  
pp. 1-4
Author(s):  
Elena Felicia Beznea ◽  
Ionel Chirica ◽  
Adrian Presura ◽  
Ionel Iacob
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Sandwich Structure ◽  
High Strength ◽  
Total Weight ◽  
External Loading ◽  
Strength Analysis ◽  
Allowable Stress ◽  
The Finite Element Method ◽  
Inland Navigation

The paper is treating the strength analysis of the main deck structure of an inland navigation catamaran for 30 passengers. The main deck should have high stiffness and high strength to resist to external loading and endure high stresses from combined bending and torsion loads. Different materials for sandwich structure of the deck have been analysed by using the Finite Element Method in order to determine the solution which accomplish better designing criteria regarding allowable stress and deformations and total weight.

Influence of the contact with friction on the deformation behavior of advanced high strength steels in the Nakajima test

2021 ◽  
pp. 030932472110212
Author(s):  
Mohammad Mehdi Kasaei ◽  
Marta C Oliveira
Keyword(s):  
Finite Element ◽  
Friction Coefficient ◽  
Strain Rate ◽  
Contact Pressure ◽  
Deformation Behaviour ◽  
High Strength Steels ◽  
High Strength ◽  
Advanced High Strength Steels ◽  
Deformation Mechanics ◽  
Nakajima Test

This work presents a new understanding on the deformation mechanics involved in the Nakajima test, which is commonly used to determine the forming limit curve of sheet metals, and is focused on the interaction between the friction conditions and the deformation behaviour of a dual phase steel. The methodology is based on the finite element analysis of the Nakajima test, considering different values of the classic Coulomb friction coefficient, including a pressure-dependent model. The validity of the finite element model is examined through a comparison with experimental data. The results show that friction affects the location and strain path of the necking point by changing the strain rate distribution in the specimen. The strain localization alters the contact status from slip to stick at a portion of the contact area from the pole to the necking zone. This leads to the sharp increase of the strain rate at the necking point, as the punch rises further. The influence of the pressure-dependent friction coefficient on the deformation behaviour is very small, due to the uniform distribution of the contact pressure in the Nakajima test. Moreover, the low contact pressure range attained cannot properly replicate real contact condition in sheet metal forming processes of advanced high strength steels.

Study on the Local Buckling Behavior of Steel Equal Angle Members under Axial Compression with the Steel Strength Variation

2011 ◽  
Vol 374-377 ◽  
pp. 2430-2436
Author(s):  
Gang Shi ◽  
Zhao Liu ◽  
Yong Zhang ◽  
Yong Jiu Shi ◽  
Yuan Qing Wang
Keyword(s):  
Finite Element ◽  
Axial Compression ◽  
High Strength Steel ◽  
Local Buckling ◽  
Steel Structures ◽  
High Strength ◽  
Element Analysis ◽  
Equal Angle ◽  
Buckling Behavior ◽  
Steel Strength

High strength steel sections have been increasingly used in buildings and bridges, and steel angles have also been widely used in many steel structures, especially in transmission towers and long span trusses. However, high strength steel exhibits mechanical properties that are quite different from ordinary strength steel, and hence, the local buckling behavior of steel equal angle members under axial compression varies with the steel strength. However, there is a lack of research on the relationship of the local buckling behavior of steel equal angle members under axial compression with the steel strength. A finite element model is developed in this paper to analyze the local buckling behavior of steel equal angle members under axial compression, and study its relationship with the steel strength and the width-to-thickness ratio of the angle leg. The finite element analysis (FEA) results are compared with the corresponding design method in the American code AISC 360-05, which provides a reference for the related design.

Virtual trabecular bone models and their mechanical response

2008 ◽  
Vol 222 (8) ◽  
pp. 1185-1195 ◽  
Author(s):  
F E Donaldson ◽  
P Pankaj ◽  
A H Law ◽  
A H Simpson
Keyword(s):  
Finite Element ◽  
Trabecular Bone ◽  
Mechanical Behaviour ◽  
Mechanical Response ◽  
Elastic Response ◽  
Anatomical Site ◽  
Virtual Samples ◽  
Micro Level ◽  
Architectural Characteristics

The study of the mechanical behaviour of trabecular bone has extensively employed micro-level finite element (μFE) models generated from images of real bone samples. It is now recognized that the key determinants of the mechanical behaviour of bone are related to its micro-architecture. The key indices of micro-architecture, in turn, depend on factors such as age, anatomical site, sex, and degree of osteoporosis. In practice, it is difficult to acquire sufficient samples that encompass these variations. In this preliminary study, a method of generating virtual finite element (FE) samples of trabecular bone is considered. Virtual samples, calibrated to satisfy some of the key micro-architectural characteristics, are generated computationally. The apparent level elastic and post-elastic mechanical behaviour of the generated samples is examined: the elastic mechanical response of these samples is found to compare well with natural trabecular bone studies conducted by previous investigators; the post-elastic response of virtual samples shows that material non-linearities have a much greater effect in comparison with geometrical non-linearity for the bone densities considered. Similar behaviour has been reported by previous studies conducted on real trabecular bone. It is concluded that virtual modelling presents a potentially valuable tool in the study of the mechanical behaviour of trabecular bone and the role of its micro-architecture.

Contrastive Study on Finite Element Models of High-Strength Pipelines Crossing Active Faults

2016 ◽  
Vol 850 ◽  
pp. 957-964
Author(s):  
Wei Zheng ◽  
Hong Zhang ◽  
Xiao Ben Liu ◽  
Le Cai Liang ◽  
Yin Shan Han
Keyword(s):  
Finite Element ◽  
Design Method ◽  
Active Faults ◽  
Shell Element ◽  
High Strength ◽  
Element Model ◽  
Beam Element ◽  
Finite Element Models ◽  
Fixed Boundary ◽  
Equivalent Boundary

There is a potential for major damage to the pipelines crossing faults, therefore the strain-based design method is essential for the design of buried pipelines. Finite element models based on soil springs which are able to accurately predict pipelines’ responses to such faulting are recommended by some international guidelines. In this paper, a comparative analysis was carried out among four widely used models (beam element model; shell element model with fixed boundary; shell element model with beam coupled; shell element model with equivalent boundary) in two aspects: differences of results and the efficiency of calculation. The results show that the maximum and minimum strains of models coincided with each other under allowable strain and the calculation efficiency of beam element model was the highest. Besides, the shell element model with beam coupled or equivalent boundary provided the reasonable results and the calculation efficiency of them were higher than the one with fixed boundary. In addition, shell element model with beam coupled had a broader applicability.

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