Effect of Oriented Platy Filler on the Fracture Mechanism of Elastomers

1988 ◽  
Vol 61 (4) ◽  
pp. 619-629 ◽  
Author(s):  
Roger J. Eldred
Keyword(s):  
Fracture Energy ◽  
Failure Modes ◽  
Fold Increase ◽  
Fracture Pattern ◽  
Shear Mode ◽  
Cohesive Fracture ◽  
Lateral Direction ◽  
Reinforcing Agent ◽  
Interlaminar Shear ◽  
Energy Absorbing

Abstract Through an investigation of tension fatigue failure modes, oriented platy fillers have been found to provide elastomers with a unique failure mechanism which allows the elastomer to resist destructive crack growth. Samples of chlorosulfonated polyethylene containing talc as a reinforcing agent failed in an interlaminar shear mode, parallel to the applied stress. This fracture pattern resulted from diversion of the classical Griffith-type crack which would normally proceed perpendicularly to the stress. The theoretical criterion for diversion requires the adhesive fracture energy, Gad, in the plane of the diverted crack to be about one-tenth of the cohesive fracture energy, Gco, in the plane of the Griffith crack. Measured values of the fracture energies determined by 180° peel (Gad) tests and trouser tear (Gco) tests showed that the talc-filled elastomer satisfied the criterion. However, the criterion was met, not by the introduction of planes of weakness in the lateral direction (thereby reducing Gad), but by a more than five-fold increase in the cohesive fracture energy over that measured for a control containing carbon black as reinforcing agent. Examination of the fractured surfaces by scanning electron microscopy showed that the increase in Gco was due to the many energy absorbing fracture paths down which the tear was diverted as it advanced through the elastomer. Besides exhibiting high tear energies, the elastomer was found to be highly insensitive to stress risers such as razor cuts. The combination of tear resistance and insensitivity to flaws leads to a prediction that elastomers containing oriented platy fillers will exhibit increased strength and durability. This first practical system affording crack diversion has special application to hoses and topologically similar shapes such as boots and sleeves.

scholarly journals Energy Absorption Characteristics of Foam Filled Tri Circular Tube under Bending Loads

2021 ◽  
Vol 15 ◽  
pp. 159-164
Author(s):  
Fauzan Djamaluddin
Keyword(s):  
Energy Absorption ◽  
Failure Modes ◽  
Circular Tube ◽  
Comparative Investigation ◽  
Tubular Structures ◽  
Vehicle Engineering ◽  
Bending Resistance ◽  
Bending Loads ◽  
Foam Filled ◽  
Energy Absorbing

In this study, the researcher carried out a comparative investigation of the crashworthy features of different tubular structures with a quasi-static three bending point, like the foam-filled two and tri circular tube structures. Energy absorption capacities and failure modes of different structures are also studied. Furthermore, the general characteristics are investigated and compared for instance the energy absorption, specific energy absorption and energy-absorbing effectiveness for determining the potential structural components that can be used in the field of vehicle engineering. Experimental results indicated that under the bending conditions, the tri foam-filled structures were higher crashworthiness behaviour than the two foam-filled circular structures. Therefore, this study recommended the use of crashworthy structures, such as foam-filled tri circular tubes due to the increased bending resistance and energy-absorbing effectiveness.

scholarly journals Rheology, fresh and hardened properties of self-consolidating concrete utilizing metal and PVA polymer fibers

2021 ◽  
Author(s):  
Moustafa M Sammour
Keyword(s):  
Flexural Strength ◽  
Fracture Energy ◽  
Strength Properties ◽  
Fiber Reinforced Concrete ◽  
Fiber Types ◽  
Fiber Reinforced ◽  
Segregation Index ◽  
Self Consolidating Concrete ◽  
Funnel Flow ◽  
Energy Absorbing

Fiber reinforced self-consolidating concrete (FRSCC) has a tremendous potential to be used in construction industry as it combines the advantagees of both self-consolidating concrete (SCC) and fiber reinforced concrete (FRC). 18 concrete mixtures were developed by incorporating differenct volumes (0 to 0.3) of polyvinyl alchohol (PVA) and metallic fibers. Fresh, rheological, mechanical and durability (in terms of chloride penetration resistance) properties of all FRSCC mixtures were evaluated. The influences of fiber types/size/ dosages and fiber combination (used in hybrid mixes) on fresh (slump flow, L-box passing ability, V-funnel flow time and segregation index), rheological (plastic viscosity and yield stress) and hardened (fracture energy and compressive/flexural/splitting tensile strength) properties were critically analyzed to examine the relationships among various properties as well as to suggest suitable FRSCC mixtures. The fibers (especially metallic ones) wre more effective in increasing the fracture energy of FRSCC than compressive/splitting tensile/flexural strength. A fracture energy gain of about 730% was observed (which is substantial) compared to 10% of compressive strength, 39% of splitting tensil strength and 124% of flexural strength. The improved strength and fracture energy of FRSCC mixtures can significantly reduce the amount of tensile reinforcement and subsantially increase the energy absorbing capacity of concrete structures.

Hybrid composite laminates reinforced with flax-basalt-glass woven fabrics for lightweight load bearing structures

2020 ◽  
pp. 152808372096074
Author(s):  
Mohamed A Attia ◽  
Marwa A Abd El-baky ◽  
Mostafa M Abdelhaleem ◽  
Mohamed A Hassan
Keyword(s):  
Mechanical Properties ◽  
Composite Laminates ◽  
Failure Modes ◽  
Woven Fabrics ◽  
Plane Shear ◽  
Load Bearing ◽  
Impact Properties ◽  
Basalt Glass ◽  
Interlaminar Shear ◽  
The Impact

An experimental investigation on the mechanical performance of interlayer hybrid flax-basalt-glass woven fabrics reinforced epoxy composite laminates has been performed. The tensile, flexural, in-plane shear, interlaminar shear, bearing, and impact properties of the fabricated laminates were investigated. Test specimens were fabricated using vacuum bagging process. Failure modes of all specimens were recorded and discussed. Results proved that the mechanical properties of flax-basalt-glass hybrid laminates are highly dominated by the reinforcement combinations and plies stacking sequence. Hybridizing flax fiber reinforced composite with basalt and/or glass fabrics provides an effective method for enhancing its tensile, flexural, in-plane shear, interlaminar shear, and bearing properties as well as controls the impact strength of the composite. The fabricated hybrids are found to have good specific mechanical properties benefits. Amongst the studied flax/basalt/glass hybrids, FBGs has the highest tensile properties, GBFs has the highest flexural and impact properties, and GFBs has the best shear and bearing properties. Flax-basalt-glass hybrid composites with different layering sequence seem to be an appropriate choice for lightweight load bearing structures.

scholarly journals 3D-printed cellular tips for tuning fork atomic force microscopy in shear mode

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Liangdong Sun ◽  
Hongcheng Gu ◽  
Xiaojiang Liu ◽  
Haibin Ni ◽  
Qiwei Li ◽  
...  
Keyword(s):  
Atomic Force Microscopy ◽  
Shear Mode ◽  
Unique Contribution ◽  
Force Microscopy ◽  
Atomic Force ◽  
Afm Tips ◽  
3D Printed ◽  
Architectured Material ◽  
Energy Absorbing ◽  
Absorption Field

AbstractConventional atomic force microscopy (AFM) tips have remained largely unchanged in nanomachining processes, constituent materials, and microstructural constructions for decades, which limits the measurement performance based on force-sensing feedbacks. In order to save the scanning images from distortions due to excessive mechanical interactions in the intermittent shear-mode contact between scanning tips and sample, we propose the application of controlled microstructural architectured material to construct AFM tips by exploiting material-related energy-absorbing behavior in response to the tip–sample impact, leading to visual promotions of imaging quality. Evidenced by numerical analysis of compressive responses and practical scanning tests on various samples, the essential scanning functionality and the unique contribution of the cellular buffer layer to imaging optimization are strongly proved. This approach opens new avenues towards the specific applications of cellular solids in the energy-absorption field and sheds light on novel AFM studies based on 3D-printed tips possessing exotic properties.

Experimental Study on Interlaminar Shear Properties of T300/BMI Composite Laminates

2013 ◽  
Vol 718-720 ◽  
pp. 157-161
Author(s):  
Zong Hong Xie ◽  
Hai Han Liu ◽  
Jian Zhao ◽  
Jun Feng Sun ◽  
Fei Peng ◽  
...  
Keyword(s):  
Composite Laminates ◽  
Shear Test ◽  
Failure Modes ◽  
Shear Failure ◽  
Test Method ◽  
Test Results ◽  
Shear Properties ◽  
Test Fixture ◽  
Iosipescu Shear Test ◽  
Interlaminar Shear

A modified test fixture to measure the shear properties of composite laminates was designed and manufactured based upon Iosipescu shear test method. Tests on interlaminar shear propertis of T300/BMI composite laminates were conducted according to ASTM D 5379 test standard. Interlaminar shear stress/strain curves and shear failure modes were obtained. The test results showed that the modified shear test fixture and test method were effective in measuring the shear properties of composite laminates.

Fracture Energy of Elastomers in Mode I (Cleavage) and Mode III (Lateral Shear)

1975 ◽  
Vol 48 (5) ◽  
pp. 896-901 ◽  
Author(s):  
A. Ahagon ◽  
A. N. Gent ◽  
H. J. Kim ◽  
Y. Kumagai
Keyword(s):  
Fracture Energy ◽  
Strain Energy ◽  
Sheet Thickness ◽  
Shear Mode ◽  
Mode I ◽  
Input Energy ◽  
Mode Iii ◽  
Lateral Shear ◽  
Test Sheet ◽  
Filled Elastomers

Abstract Attention has been drawn here to three different reasons why measurements of fracture energy by different methods may not agree: (1) When the test involves propagation of a tear by stored strain energy, as in the method shown in Figure 1, the energy available to cause rupture will be less than that supplied, because of dissipation within the elastomer. Calculation of the fracture energy on the basis of input energy would then lead to an overestimate, by about 100 per cent or more for typical filled elastomers. (2) As shown in Figures 4a and 5, the tear path is sometimes wider than the thickness of the test sheet. In consequence, fracture energy calculated from the sheet thickness would be too large, by about 40 per cent in the cases considered here. (3) Even when allowance is made for the true width of the tear path, measurements of fracture energy in shear (Mode III) are about 50 per cent larger than in cleavage (Mode I). This is attributed to frictional work expended in sliding the rough torn surfaces past each other.

Flexural Fatigue of Unbalanced Glass-Carbon Hybrid Composites

2014 ◽  
Vol 136 (4) ◽  
Author(s):  
Kevin B. Cox ◽  
Nils-Petter Vedvik ◽  
Andreas T. Echtermeyer
Keyword(s):  
Failure Modes ◽  
Hybrid Composites ◽  
Turbine Blades ◽  
Matrix Cracking ◽  
Shear Stresses ◽  
Interlaminar Stresses ◽  
Wind Turbine Blades ◽  
Flexural Fatigue ◽  
Glass Carbon ◽  
Interlaminar Shear

Unbalanced composite layups with bend-twist coupling show potential for aeroelastic tailoring in wind turbine blades. Before these materials can be implemented, their responses to long term cyclic loading must be considered. This paper studies the fatigue characteristics of an unbalanced glass-carbon hybrid laminate with a [45glass/−45glass/24carbon/24carbon]s layup. Flexural fatigue was performed at 7 different load magnitudes up to 1 × 106 cycles to characterize the failure modes and fatigue life of the composite. Stiffness degradation occurred on the tension side due to matrix cracking and small regions of delamination on the glass plies, whereas the failure mechanism of the laminate was by delamination between the glass and carbon. S-N curves were generated from experimental results and static finite element analyses (FEA) based on interlaminar shear stresses and were compared with laminates from previous literature. It was determined that the interlaminar stresses were influenced more so by the lower stiffness of the unbalanced layup than by the induced torsional deflections: leading to the conclusion that bend-twist coupling had little influence on flexural fatigue of glass-carbon hybrid composites.

Multi-Layer Silicon Nitride Laminates Exhibiting High Fracture Toughness and Crack Deflection

2007 ◽  
Vol 280-283 ◽  
pp. 1863-1868 ◽  
Author(s):  
Gurdial Blugan ◽  
Nina Orlovskaya ◽  
Mike Lewis ◽  
Jakob Kübler
Keyword(s):  
Fracture Toughness ◽  
Silicon Nitride ◽  
Fold Increase ◽  
Crack Deflection ◽  
High Fracture Toughness ◽  
High Fracture ◽  
Monolithic Ceramics ◽  
Energy Absorbing

Si3N4-TiN based multi-layer ceramics laminates have been produced. With external compressive layers, laminates with a three-fold increase in KIc over the monolithic ceramics have been realised. When external tensile layers are used in conjunction with thin internal compressive layers, energy absorbing crack deflection and bifurcation processes are observed.

scholarly journals Structural behaviour of composite slab with high performance concretes

2021 ◽  
Author(s):  
Haile Mengistu
Keyword(s):  
High Performance ◽  
Failure Modes ◽  
Experimental Investigations ◽  
Structural Behaviour ◽  
Interface Shear ◽  
Composite Slab ◽  
Composite Slabs ◽  
Energy Absorbing ◽  
Steel Deck ◽  
Bond Characteristics

Composite slabs with profiled steel deck and concrete toping have gained wide acceptance as they lead to faster, lighter and economical construction. Extensive research works have been conducted on the behaviour of composite slabs to study their structural behavior and steel-concrete interface shear bond resistance which primarily governs the failure. However, the use of emerging highly durable engineered cementitous composite (ECC) in composite slab is new and no research has been conducted yet. High strain hardening and intrinsic crack width characteristics of ECC can significantly improve structural performance of composite slabs through enhancing ductility, energy absorbing capacity and steel-concrete shear bond. In this study, experimental investigations are conducted to evaluate the shear bond characteristics of composite slabs made with ECC and conventional self-consolidating concrete (SCC) using Code based m-k method. Twelve slab specimens having variable shear span and two types of profiled steel deck were tested under four point loading. The performance of ECC and SCC composite slabs are compered based on load-deflection response, stress-strain development in concrete and steel, failure modes, energy absorbing capacity and steel-concrete shear bond parameters (m and k) and bond stress.

scholarly journals Theoretical and Experimental Studies of Two-Span Reinforced Concrete Deep Beams and Comparisons with Strut-and-Tie Method

2021 ◽  
Vol 2021 ◽  
pp. 1-16
Author(s):  
Mahsa Zargarian ◽  
Alireza Rahai
Keyword(s):  
Large Scale ◽  
Failure Modes ◽  
Experimental Studies ◽  
Nonlinear Finite Element ◽  
Shear Mode ◽  
Design Codes ◽  
Load Prediction ◽  
Deep Beams ◽  
Strut And Tie ◽  
Truss Model

Regarding the complicated behavior of continuous deep beams, a research program including three parts was conducted. First part: three continuous concrete deep beams with different shear span-to-depth ratios (a/h) were tested. The effects of varying a/h ratio on ultimate strength and failure modes were investigated. Second part: the nonlinear finite element (FE) analyses were performed to simulate the experimental specimens and 21 large-scale continuous deep beams. The main parameters investigated were a/h ratio from 0.33 to 2 and f c ′ considered 40 MPa, 60 MPa, and 80 MPa. Third part: the strut-and-tie modeling of different design codes and indeterminate strut-tie method were studied for continuous deep beams. Regardless of the a/h ratio, all beam specimens failed in shear mode with main diagonal cracks. Although EC2 load prediction was conservative for all beam models, the ACI and CSA predictions for concrete deep beams with high compressive strength were unsafe. The indeterminate truss model showed closer results to FE analysis in comparison with ACI, EC2, and CSA strut-and-tie method.

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