scholarly journals Material heterogeneity in cancellous bone promotes deformation recovery after mechanical failure

2016 ◽  
Vol 113 (11) ◽  
pp. 2892-2897 ◽  
Author(s):  
Ashley M. Torres ◽  
Jonathan B. Matheny ◽  
Tony M. Keaveny ◽  
David Taylor ◽  
Clare M. Rimnac ◽  
...  
Keyword(s):  
Cancellous Bone ◽  
High Strength ◽  
Tissue Level ◽  
Stress Concentrations ◽  
Opposite Pattern ◽  
Initial Shape ◽  
Material Heterogeneity ◽  
Strength And Stiffness ◽  
Interior Damage ◽  
Deformation Recovery

Many natural structures use a foam core and solid outer shell to achieve high strength and stiffness with relatively small amounts of mass. Biological foams, however, must also resist crack growth. The process of crack propagation within the struts of a foam is not well understood and is complicated by the foam microstructure. We demonstrate that in cancellous bone, the foam-like component of whole bones, damage propagation during cyclic loading is dictated not by local tissue stresses but by heterogeneity of material properties associated with increased ductility of strut surfaces. The increase in surface ductility is unexpected because it is the opposite pattern generated by surface treatments to increase fatigue life in man-made materials, which often result in reduced surface ductility. We show that the more ductile surfaces of cancellous bone are a result of reduced accumulation of advanced glycation end products compared with the strut interior. Damage is therefore likely to accumulate in strut centers making cancellous bone more tolerant of stress concentrations at strut surfaces. Hence, the structure is able to recover more deformation after failure and return to a closer approximation of its original shape. Increased recovery of deformation is a passive mechanism seen in biology for setting a broken bone that allows for a better approximation of initial shape during healing processes and is likely the most important mechanical function. Our findings suggest a previously unidentified biomimetic design strategy in which tissue level material heterogeneity in foams can be used to improve deformation recovery after failure.

scholarly journals Materials for Automotive Lightweighting

2019 ◽  
Vol 49 (1) ◽  
pp. 327-359 ◽  
Author(s):  
Alan Taub ◽  
Emmanuel De Moor ◽  
Alan Luo ◽  
David K. Matlock ◽  
John G. Speer ◽  
...  
Keyword(s):  
Galvanic Corrosion ◽  
Low Carbon Steel ◽  
High Strength Steels ◽  
High Strength ◽  
Low Carbon ◽  
New Materials ◽  
Specific Strength ◽  
Advanced High Strength Steels ◽  
Strength And Stiffness ◽  
The Cost

Reducing the weight of automobiles is a major contributor to increased fuel economy. The baseline materials for vehicle construction, low-carbon steel and cast iron, are being replaced by materials with higher specific strength and stiffness: advanced high-strength steels, aluminum, magnesium, and polymer composites. The key challenge is to reduce the cost of manufacturing structures with these new materials. Maximizing the weight reduction requires optimized designs utilizing multimaterials in various forms. This use of mixed materials presents additional challenges in joining and preventing galvanic corrosion.

scholarly journals Biomimetic Composites with Enhanced Toughening Using Silk Inspired Triblock Proteins and Aligned Nanocellulose Reinforcements

2019 ◽  
Author(s):  
Pezhman Mohammadi ◽  
A. Sesilja Aranko ◽  
Christopher P. Landowski ◽  
Olli Ikkala ◽  
Kristaps Jaudzems ◽  
...  
Keyword(s):  
Spider Silk ◽  
Cellulose Nanofibrils ◽  
High Strength ◽  
Beta Sheets ◽  
Conformational Switching ◽  
Multiple Length Scales ◽  
The Matrix ◽  
Strength And Stiffness ◽  
Flow Alignment

Silk and cellulose are biopolymers that show a high potential as future sustainable materials.They also have complementary properties, suitable for combination in composite materials where cellulose would form the reinforcing component and silk the tough matrix. Therein, a major challenge concerns balancing structure and properties in the assembly process. We used recombinant proteins with triblock architecture combining structurally modified spider silk with terminal cellulose affinity modules. Flow-alignment of cellulose nanofibrils and triblock protein allowed a continuous fiber production.The protein assembly involved phase separation into concentrated coacervates, with subsequent conformational switching from disordered structures to beta sheets. This gave the matrix a tough adhesiveness, forming a new composite material with high strength and stiffness combined with increased toughness. We show that versatile design possibilities in protein engineering enable new fully biological materials, and emphasize the key role of controlled assembly at multiple length scales for realization.<br>

Experimental study on seismic behaviors of beam with concrete-encased steel truss

2018 ◽  
Vol 21 (13) ◽  
pp. 2018-2029
Author(s):  
Xide Zhang ◽  
Zhiheng Deng ◽  
Xiaofang Deng ◽  
Jingwei Ying ◽  
Tao Yang ◽  
...  
Keyword(s):  
High Strength ◽  
Force Model ◽  
Restoring Force ◽  
Restoring Force Model ◽  
Steel Truss ◽  
Different Types ◽  
Energy Dissipation Capacity ◽  
Load Displacement ◽  
Strength And Stiffness ◽  
Seismic Behaviors

To evaluate the ductility and energy dissipation capacity of the beam with concrete-encased steel truss, eight specimens with different types of steel truss, reinforcement ratios, and shear span ratios were tested by low-cyclic loading regime. The results indicated that beams with concrete-encased steel truss performed plumped load–displacement hysteretic loops as well as high strength and stiffness. Moreover, cross-web members improved their seismic behavior more effectively than non-cross-web members. Finally, the restoring force model of concrete-encased steel truss beam is proposed in accordance with the experimental results, which can be used to predict the load–displacement behavior of concrete-encased steel truss beam. The results could also provide a reference for the design and application of concrete-encased steel truss beam in practice.

Influence of the base material on the mechanical behaviors of polycrystal-like meta-crystals

2021 ◽  
pp. 2150004
Author(s):  
J. Lertthanasarn ◽  
C. Liu ◽  
M.-S. Pham
Keyword(s):  
Synergistic Effects ◽  
High Surface ◽  
Base Material ◽  
High Strength ◽  
Yield Stability ◽  
Yield Behavior ◽  
Specific Strength ◽  
Base Materials ◽  
Lattice Materials ◽  
Strength And Stiffness

Architected lattice metamaterials offer extraordinary specific strength and stiffness that can be tailored through the architecture. Meta-crystals mimic crystalline strengthening features in crystalline alloys to obtain high strength and improved post-yield stability of lattice materials. This study investigates synergistic effects of the base material’s intrinsic crystalline microstructure and architected polycrystal-like architecture on the mechanical behavior of architected metamaterials. Four different polygrain-like meta-crystals were fabricated from 316L, Inconel 718 (IN718) and Ti6Al4V via laser powder bed fusion (L-PBF). While the elastic modulus of the meta-crystals did not vary significantly with the base material or the number of meta-grains, the strength of the meta-crystals showed strong increasing correlation with reducing the size of meta-grains. The differences between meta-crystals made by the three alloys were the most substantial in the post-yield behavior, where the 316L meta-crystals were the most stable while Ti6Al4V meta-crystals were the most erratic. The differences in the post-yield behavior were attributed to the base material’s ductility and intrinsic work-hardening. For all base materials, increasing the number of meta-grains improved the post-yield stability of meta-crystals. The tolerance to the processing defects also differed with the base material. Detrimental defects such as the high surface roughness on the downskin of the struts or the large, irregularly shaped pores near the surface of the struts led to early strut fracture in Ti6Al4V meta-crystals. In contrast, ductile IN718 was able to tolerate such defects, enabling the most significant synergistic strengthening across lengthscales to achieve architected materials of low relative density, but with a very high strength and an excellent energy absorption.

scholarly journals Improved numerical analysis of structures reinforced by composite FRP: Hygrothermal and prestressing loads with taper effect

2019 ◽  
Vol 28 ◽  
pp. 096369351985836
Author(s):  
Mohammed Amine Hebbaz ◽  
Bachir Kerboua ◽  
Mostapha Tarfaoui
Keyword(s):  
Interfacial Shear Stress ◽  
High Strength ◽  
Interfacial Stress ◽  
Steel Plates ◽  
Steel Beams ◽  
Original Research ◽  
Frp Composites ◽  
Prestressing Force ◽  
Numerical Finite Element ◽  
Strength And Stiffness

Fiber-reinforced polymer (FRP) composites are becoming suitable and substantial materials in repairing and replacing conventional metallic materials because of their high strength and stiffness. Steel beams can be strengthened in flexure using bonded FRP or using steel plates. In such plated beams, shear forces develop in the bonded beam and these will be transferred to the FRP plate via the adhesion technique. Thus, the interfacial shear stress and normal stress will develop consequently, and debonding may occur at the FRP plate ends due to high interfacial stress values in this area. This original research aims to study the debonding phenomenon using an analytical and a numerical finite element models, in order to identify the interfacial stresses of a steel beam strengthened by the FRP plate with taper model, taking into account a new coupled approach of prestressing force and hygrothermal effect. This article explores the effects of various parameters, such as geometrical and physical properties, on the stress behavior of FRP composites.

scholarly journals Studying the influence of the cross section height on the distribution of the internal efforts of wooden glued beams

2019 ◽  
Vol 135 ◽  
pp. 03048
Author(s):  
Sergei Prokhorov
Keyword(s):  
Cross Section ◽  
High Strength ◽  
Large Error ◽  
Environmental Friendliness ◽  
High Rise ◽  
Reinforced Beams ◽  
Flexural Member ◽  
Strength And Stiffness ◽  
Capital Construction ◽  
Wooden Structures

Since ancient times, wooden structures have been used by man for the construction of buildings and facilities. For many centuries, the structural elements of buildings and facilities made of wood have been the main ones, and still have broad prospects for use in modern capital construction, as they have sufficient high strength and stiffness, are reliable and durable, while having a small mounting weight. In particular, a number of Western countries are already erecting high-rise buildings using a framework of laminated wood constructions. The indisputable advantage of wooden structures is environmental friendliness. However, with all the harmony of the wood structure, its tracheid’s are not standard, which is the main reason for the variability of its mechanical properties. With alteration of a cross-section of flexural member, the nature of the load distribution, as well as the nature of the fracture, changes. An additional factor that affecting the force distribution is the nature of the reinforcement and methods of the reinforcement fixing methods. The methods used to calculate the “low” reinforced beams often give a large error in the calculation of “high” beams. In the work, a rational methodology for calculating wooden glued reinforced beams with symmetrical reinforcement is determined.

scholarly journals Simplified Material Solution for Orthotropic Symmetrical GFRP Laminates for Structural Facades

2019 ◽  
Vol 2019 ◽  
pp. 1-15
Author(s):  
Yuchao Zhao ◽  
Xu Jiang ◽  
Qilin Zhang ◽  
Xuhong Qiang
Keyword(s):  
Design Theory ◽  
High Strength ◽  
Fiber Reinforced Polymer ◽  
Free Form ◽  
Reinforced Polymer ◽  
Glass Fiber Reinforced ◽  
Complex Design ◽  
Low Weight ◽  
Strength And Stiffness ◽  
Material Solution

GFRP (glass-fiber-reinforced polymer), as a composite material, possesses many favorable properties including high strength and low weight and is amenable to unique processing methods; therefore, it is a potential free-form surface material. However, the complex design theory owing to anisotropy limits its application. Thus, a simplified material solution becomes significant. In this study, the strength and stiffness of orthotropic symmetrical GFRP laminates are derived theoretically, and a simplified material solution is proposed to simplify the anisotropy as isotropy. Then, using the numerical simulation of an actual orthotropic symmetrical GFRP laminate free-form facade structure, the effectiveness of the simplified material solution is analyzed and evaluated. This solution can provide guidance for similar GFRP facades and further promote the application of GFRP in engineering.

Advanced Oxidation Protection System for Carbon-Carbon Composites

1989 ◽  
Author(s):  
D. A. Eitman ◽  
R. W. Kidd ◽  
R. B. Dirling
Keyword(s):  
Advanced Oxidation ◽  
High Strength ◽  
Carbon Composite ◽  
Protection System ◽  
Carbon Composites ◽  
Oxidation Protection ◽  
Low Thermal Expansion ◽  
The Matrix ◽  
Strength And Stiffness ◽  
Orthotropic Properties

Carbon-carbon composites possess a number of desirable attributes including low density, high strength and stiffness at temperatures well beyond the capabilities of refractory alloys, low thermal expansion coefficient, tailorable orthotropic properties, absence of strategic materials, and resistance to thermal shock, fatigue, and brittle failures. However, for many applications of interest (such as aircraft and aerospace vehicle structure and engines) resistance to oxidation in high-temperature air or engine exhaust streams is a requirement which is not satisfied by unprotected carbon-carbon composites. The elements of an advanced oxidation protection system for carbon-carbon composites are described in this paper. The system is comprised of both an oxidation resistant coating intended to provide the primary barrier to oxygen ingress and inhibitors added to the matrix of the carbon-carbon composite to increase its oxidation resistance without significant losses in mechanical properties. The composite inhibition system is designed to be complementary to the coating and to enhance its long-term performance. A description of the principal elements of the system is presented along with recent test data and current research directions.

Forming Potential of Steel/Polymer/Steel Sandwich Composites with Local Plate Inserts

2012 ◽  
Vol 706-709 ◽  
pp. 681-686 ◽  
Author(s):  
Heinz Palkowski ◽  
Olga Sokolova ◽  
Adele Carradò
Keyword(s):  
Deep Drawing ◽  
High Performance ◽  
High Strength ◽  
Metal Plate ◽  
Elastic Behaviour ◽  
Forming Limit ◽  
Sandwich Composites ◽  
Strength And Stiffness ◽  
Naval Engineering ◽  
Forming Behaviour

High-performance metal/polymer/metal hybrid sandwich composites are attractive materials for lightweight constructions in automotive, aerospace and naval engineering world-wide. Due to the excellent combination of mechanical, thermal and elastic properties and, as a result of high forming potential, they can be used in areas of high vibration, where high damping properties of the polymer are demanded and at the same time high strength and stiffness are given by the metal. Disadvantages can be given in case of mechanical or thermal joining of these polymer-based sandwiches because of the elastic behaviour as well as low melting temperature of the polymer. Local metal plate insertions in the soft core at the place of joining can be a solution for such kind of problems. But forming behaviour of sandwich materials with and without local inlays differs strongly. Sandwich composites of that type were produced by roll-bonding. Their quality and their position were controlled by Lockin thermography. The forming behaviour of sandwiches with different geometry, size, type and the position of the inlays was tested by deep drawing and bending and analysed with the help of digital photogrammetry and compared to experimentally obtained mechanical properties. As a result, the local inlays, as well as their geometry, size and type strongly influence the forming limit conditions. The differences in flow behaviour of non-reinforced and reinforced sandwich regions after deep drawing and bending will be presented, as well as the influence of the position of the inlays.

Online determination of anisotropy during cellulose nanofibril assembly in a flow focusing device

RSC Advances ◽  
2015 ◽  
Vol 5 (24) ◽  
pp. 18601-18608 ◽  
Author(s):  
Karl M. O. Håkansson
Keyword(s):  
Cellulose Nanofibrils ◽  
High Strength ◽  
Cellulose Nanofibril ◽  
Flow Focusing ◽  
Strength And Stiffness

In order to utilize the high strength and stiffness of cellulose nanofibrils in a macroscopic material or composite, the structure of the elongated fibrils in the material must be controlled.

Sign in / Sign up

Export Citation Format

Share Document