Strain Rate Effect on Out of Plane Shear Strength of Fiber Composites

2007 ◽  
Vol 345-346 ◽  
pp. 725-728
Author(s):  
Jia Lin Tsai ◽  
Jui Ching Kuo
Keyword(s):  
Shear Strength ◽  
Strain Rate ◽  
Shear Strain ◽  
Fiber Composites ◽  
Strain Rate Effect ◽  
Rate Effect ◽  
Strength Analysis ◽  
Shear Strain Rate ◽  
Plane Shear ◽  
Out Of Plane

This research aims to investigate strain rate effect on the out of plane shear strength of unidirectional fiber composites. Both glass/epoxy and graphite/epoxy composites were considered in this study. To demonstrate strain rate effect, composite brick specimens were fabricated and tested to failure in the transverse direction at strain ranges from 10-4/s to 700/s. Experimental observations reveal that the main failure mechanism of the specimens is the out of plane shear failure taking place on the plane oriented around 30 to 35 degree to the loading direction. The corresponding out-of-plane shear strength was obtained from the uniaxial failure stress through Mohr-Coulomb strength analysis. In addition, the associated shear strain rate on the failure plane was calculated through the coordinate transformation law. Results show that the out-plane shear strength increases with the increment of the shear train rates. A semi-logarithmic function expressed in terms of the normalized shear strain rate was employed to describe the rate dependence of the out-plane shear strength.

Strain Rate Effect on Mechanical Behavior of Metallic Honeycombs Under Out-of-Plane Dynamic Compression

2015 ◽  
Vol 82 (2) ◽  
Author(s):  
Yong Tao ◽  
Mingji Chen ◽  
Yongmao Pei ◽  
Daining Fang
Keyword(s):  
Strain Rate ◽  
Present Model ◽  
Dynamic Compression ◽  
Strain Rate Effect ◽  
Numerical Results ◽  
Rate Effect ◽  
Plateau Stress ◽  
Parent Materials ◽  
Wide Range ◽  
Out Of Plane

Although many researches on the dynamic behavior of honeycombs have been reported, the strain rate effect of parent materials was frequently neglected, giving rise to the underestimated plateau stress and energy absorption (EA). In this paper, the strain rate effect of parent materials on the out-of-plane dynamic compression and EA of metallic honeycombs is evaluated by both numerical simulation and theoretical analysis. The numerical results show that the plateau stress and the EA increase significantly if the strain rate effect is considered. To account for the strain rate effect, a new theoretical model to evaluate the dynamic compressive plateau stress of metallic honeycombs is proposed by introducing the Cowper–Symonds relation into the shock theory. Predictions of the present model agree fairly well with the numerical results and existing experimental data. Based on the present model, the plateau stress is divided into three terms, namely static term, strain rate term, and inertia term, and thus the influences of each term can be analyzed quantitatively. According to the analysis, strain rate effect is much more important than inertia effect over a very wide range of impact velocity.

scholarly journals Shearing Rate Effects on Research Centre for Soft Soils (Recess) Clay Using Cone Penetration Test (CPT)

2015 ◽  
Vol 773-774 ◽  
pp. 1555-1559
Author(s):  
Azranasmarazizi Ayob ◽  
Nor Azizi Yusoff ◽  
I. Bakar ◽  
Nur Abidah Azhar ◽  
Ameer Nazrin Abd Aziz
Keyword(s):  
Shear Strength ◽  
Strain Rate ◽  
Shear Strain ◽  
Penetration Rate ◽  
Cone Penetration Test ◽  
Shear Strain Rate ◽  
Penetration Test ◽  
Cone Penetration ◽  
Rate Effects ◽  
Cpt Test

A wide range of industrial applications, on land and offshore, require the solution of time domain problems and an associated understanding of rate effects in clay soils. In recent decades many researchers have examined the correlation between shear strength of soils and variation of shear strain rate and it is generally accepted that the strength increases by 1-5% for each order of magnitude increase in shear strain rate. This paper discusses the effects of penetration rate on the penetration resistance (qc) by using cone penetration test (CPT) test setup. The research had been conducted at RECESS and cone penetration test were used in three selected range of rate which were 0.5 cm/s, 1cm/s and 5cm/s. In addition, Mackintosh probe testhad been considered as comparison with CPT test for the unconfined compressive strength. The result shows different penetration rate influenced the soil shear strength. For the slowest rate (0.5 cm/s), the shear strength was approximately 0.15% less compared to the standard rate (2 cm/s). However, for the highest rate (5 cm/s), the shear strength was 0.22% more than the reference rate (0.5 cm/s). In conclusion, it is suggested that the RECESS clay soil influenced by the rate effect and in agreement with previous research findings.

Strain rate effect on the out-of-plane dynamic compressive behavior of metallic honeycombs: Experiment and theory

2015 ◽  
Vol 132 ◽  
pp. 644-651 ◽  
Author(s):  
Yong Tao ◽  
Mingji Chen ◽  
Haosen Chen ◽  
Yongmao Pei ◽  
Daining Fang
Keyword(s):  
Strain Rate ◽  
Strain Rate Effect ◽  
Rate Effect ◽  
Compressive Behavior ◽  
Out Of Plane

Characterization of the Solid-Fluid Transition of Fine-Grained Sediments

2009 ◽  
Author(s):  
Nathalie Boukpeti ◽  
David White ◽  
Mark Randolph ◽  
Han Eng Low
Keyword(s):  
Shear Strength ◽  
Yield Strength ◽  
Strain Rate ◽  
Shear Strain ◽  
Water Content ◽  
Strength Parameter ◽  
Shear Strain Rate ◽  
Fine Grained ◽  
Rate Effects

Characterization of the strength of fine-grained sediments as they evolve from an intact seabed material to a remolded debris flow is essential to adequately model submarine landslides and their impact on pipelines and other seabed infrastructure. In the current literature, two distinct approaches for modelling this material behavior have been considered. In the soil mechanics approach, fine-grained soils are characterized by the undrained shear strength, su. The critical state framework proposes a relation between su and the water content, or void ratio of the soil. In addition, rate effects and strain softening effects are described by multiplying a reference value of su by a function of the shear strain rate or the accumulated shear strain respectively. In the fluid mechanics approach, slurries of fine-grained material are characterized by a yield strength and a viscosity parameter, which describes the change in shear stress with shear strain rate. Empirical relationships have been proposed, which relate the yield strength and the viscosity to the sediment concentration. This paper demonstrates that the two modelling approaches are essentially similar, with only some formal differences. It is proposed that the strength of fine-grained sediments can be modelled in a unified way over the solid and liquid ranges. To support this unified approach, an experimental campaign has been conducted to obtain strength measurements on various clays prepared at different water content. The testing program includes fall cone tests, vane shear tests, miniature penetrometers (T-bar and ball) and viscometer tests. Rate effects and remolding effects are investigated over a wide range of water contents spanning the domains of behavior that are usually defined separately as soil and fluid. The present paper focuses on analyzing the results of fall cone, vane shear and viscometer tests. Analysis of the results shows that the variation in shear strength over the solid and liquid ranges can be described by a unique function of water content — suitably normalized — for a given soil. Furthermore, the effect of strain rate and degree of remolding can be accounted for by multiplying the basic strength parameter by appropriate functions, which are independent of the current water content.

Investigating Strain Rate Effect on Transverse Compressive Strength of Fiber Composites

2006 ◽  
Vol 306-308 ◽  
pp. 733-738 ◽  
Author(s):  
Jia Lin Tsai ◽  
Jui Ching Kuo
Keyword(s):  
Compressive Strength ◽  
Strain Rate ◽  
Shear Failure ◽  
Split Hopkinson Pressure Bar ◽  
Rate Sensitivity ◽  
Fiber Composites ◽  
Strain Rate Effect ◽  
Rate Effect ◽  
Epoxy Composites ◽  
Hopkinson Pressure Bar

This research aims to investigate strain rate effect on transverse compressive strength of unidirectional fiber composites. Both glass/epoxy and graphite/epoxy composites were taken into account in this study. To demonstrate strain rate effect, composite brick specimens were fabricated and tested to failure in the transverse direction at strain rate ranges from 10-4/s to 500/s. For strain rate less than 1/s, the experiments were conducted by a hydraulic MTS machine. However, the higher strain rate tests were performed using a Split Hopkinson Pressure Bar (SHPB). Experimental observations reveal that the transverse compressive strengths increase corresponding to the increment of the strain rates. A semi-logarithmic function was employed to describe the rate sensitivity of the transverse compressive strength. SEM photographic on the failure surfaces depicts that for glass/epoxy composites, the failure mechanism is mainly due to the matrix shear failure, however, for the graphite/epoxy composites, it becomes the fiber and epoxy interfacial debonding which could dramatically reduce the transverse compressive strengths of the fiber composites.

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