Lamina-Based Fiber Failure Criteria and Effective Stress Failure Models

Failure analyses of laminated fibrous composite structures were conducted using the failure criteria based on a multiscale approach. The failure criteria used the stresses and strains in the fiber and matrix materials, respectively, rather than those smeared values at the lamina level. The failure modes and their respective failure criteria consist of fiber failure, matrix failure and their interface failure explicitly. In order to determine the stresses and strains at the constituent material level (i.e. fiber and matrix materials), analytical expressions were derived using a unit-cell model. This model was used for the multiscale approach for both upscaling and downscaling processes. The failure criteria are applicable to both quasi-static loading as well as dynamic loading with strain rate effects.

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Structural design and analysis of CFRP boom for concrete pump truck

Modern Physics Letters B ◽

10.1142/s0217984919400335 ◽

2019 ◽

Vol 33 (14n15) ◽

pp. 1940033 ◽

Cited By ~ 1

Author(s):

Sang-Jin Lee ◽

Il-Sup Chung ◽

Sung-Youl Bae

Keyword(s):

Structural Design ◽

Static Load ◽

Equivalent Stress ◽

Failure Criteria ◽

Steel Component ◽

Fiber Failure ◽

Composite Failure ◽

Reinforced Plastic ◽

Concrete Pump Truck ◽

Concrete Pump

This research presents structural design and analysis results of applying a composite boom structure on a Concrete Pump Truck (CPT). Carbon Fiber Reinforced Plastic (CFRP) is used to complete the structural design of the end boom to reduce the weight of the CPT. The weight of the newly designed end boom is reduced by 32% compared to the original steel component. Structural analysis is accomplished by applying static load combinations of self-weight of the boom and the weights of the pipes, the concrete and the drain hose. The results show that the tip deflection is reduced by 30% compared to the conventional end boom. Also, equivalent stress is considerably lower than the conventional design. Composite failure evaluation of the CFRP end boom is conducted by post-processing the stress results using Puck’s failure criteria. The evaluation results show that the design criteria are met on the static load of the pump truck. Specifically, it is expected that fiber failure and inter fiber failure of the boom do not occur under loading conditions according to the design evaluation results.

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Cracking behaviour of fine-grained soils: from laboratory testing to numerical modelling

E3S Web of Conferences ◽

10.1051/e3sconf/20199216004 ◽

2019 ◽

Vol 92 ◽

pp. 16004

Author(s):

Pierre Gerard ◽

Ian Murray ◽

Alessandro Tarantino

Keyword(s):

Effective Stress ◽

Failure Criterion ◽

Shear Failure ◽

Digital Camera ◽

Failure Criteria ◽

Fine Grained ◽

Fine Grained Soil ◽

Desiccation Cracking ◽

Stress States ◽

Stress Dependent

Many experimental evidences suggest that desiccation cracks in clay initiate as a result of the mobilization of soil tensile strength. However this mechanical approach disregards the cohesionless and effective stress-dependent behaviour of fine-grained soil. On the other hand recent findings in the literature suggest that effective stress-dependent shear failure criteria would be appropriate to explain the mechanisms of desiccation cracking for tensile total stress states. This work aims at assessing the validity of a shear failure criterion to predict the onset of cracking in clay forms exposed to air drying. Clay forms of various geometries were experimentally subjected to non-uniform hydraulic and mechanical boundary conditions. Time and location for crack initiation are monitored using a digital camera. Cracking experiments are then modelled in a hydro-mechanical framework using an effective-stress shear failure criterion. The comparison of simulations with experimental results for both the time and the location of cracking allows assuming that cracking occurs due to failure in shearing.

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DISCOVERING FAILURE CRITERIA OF COMPOSITES BY SPARSE IDENTIFICATION AND COMPRESSED SENSING

10.12783/asc36/35821 ◽

2021 ◽

Author(s):

FEI TAO ◽

XIN LIU ◽

HAODONG DU ◽

WENBIN YU

Keyword(s):

Compressed Sensing ◽

Failure Criterion ◽

Failure Criteria ◽

Engineering Practice ◽

The Past ◽

Failure Data ◽

Failure Models ◽

Reliable Design ◽

Fiber Modes ◽

First World

A reliable design of a composite structure needs to consider the failure of the composites. Hashin failure criterion is one of the most popular phenomenological models in engineering practice due to its simplicity of application. Although remarkable success has been achieved from the Hashin failure criterion, it does not always fit the experimental results very well. Over the past few years, a few experimental failure data have been collected. It would be of interest to leverage the existing data to improve the prediction of failure criteria. In this paper, we proposed to apply a framework that combines sparse regression with compressed sensing to discover failure criteria from data. Following the phenomenological failure models, we divided the failure of composites into tensile and compressive fiber modes, tensile and compressive matrix modes. Two examples were studied with the proposed framework. The first example was presented to demonstrate the capability of the framework. The data was generated by the Hashin failure criterion and added various magnitudes of noise. The proposed framework was implemented to discover the failure criterion from the noised data. For the second example, the proposed method was used to discover failure criteria from the experimental data which are collected from the first world wide failure exercise (WWFE I). Both examples show that the proposed method can discover the failure criteria accurately.

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A multiscale framework for predicting the mechanical properties of unidirectional non-crimp fabric composites with manufacturing induced defects

Journal of Composite Materials ◽

10.1177/0021998320958189 ◽

2020 ◽

pp. 002199832095818

Author(s):

Khizar Rouf ◽

Michael J Worswick ◽

John Montesano

Keyword(s):

Mechanical Properties ◽

Failure Criteria ◽

Structural Defects ◽

Fiber Failure ◽

Manufacturing Defects ◽

Transverse Strength ◽

Real Model ◽

Fabric Composites ◽

Out Of Plane ◽

Meso Scale

The aim of this study was to evaluate the effect of manufacturing induced in-plane tow misalignment and out-of-plane tow crimp on the mechanical properties of a heavy-tow unidirectional non-crimp fabric (UD-NCF) composite. The elastic constants and failure onset (strength) are predicted by employing a multiscale computational approach. Micro-scale finite element (FE) models that explicitly represent the fibers and matrix within the tow microstructure were used to predict the effective properties of the tow. Meso-scale FE models comprised of the homogenized tows and surrounding matrix were used to predict the properties of a UD NCF composite lamina. Four meso-scale models, identified as ideal, crimp, misalignment and real, were considered in this study. No manufacturing defects were represented in the ideal model, while out-of-plane crimp, in-plane misalignment and both out-of-plane crimp and in-plane misalignment were accounted for in the crimp model, misalignment model and real model, respectively. Predicted lamina stiffness based on the real model are found to be in an excellent agreement with available experimental data, which was not always the case for the other three models. The longitudinal and transverse strength predictions are found to be dependent on the chosen local failure criteria for each model. Max-stress and Puck’s fiber failure criteria provide an excellent estimate of longitudinal strength while the Puck’s inter-fiber failure and Tsai-Hill criteria predict transverse strength with good accuracy. The feasibility to accurately predict the mechanical properties of heavy tow non-crimp fabric composites by incorporating their inherent micro-structural defects is demonstrated in this study.

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Interpretation of vane shear tests for geotechnical stability calculations

Canadian Geotechnical Journal ◽

10.1139/cgj-2017-0209 ◽

2017 ◽

Vol 54 (12) ◽

pp. 1775-1780 ◽

Cited By ~ 4

Author(s):

George Kouretzis ◽

Jubert Pineda ◽

Kristian Krabbenhøft ◽

Lachlan Wilson

Keyword(s):

Effective Stress ◽

Slip Surface ◽

Failure Criteria ◽

Shear Tests ◽

Vane Shear Test ◽

Rate Effects ◽

Undrained Strength ◽

Geotechnical Stability ◽

The Given ◽

Theoretical Considerations

In this note we consider the problem of calibrating failure criteria for short-term stability calculations based on the results of vane shear tests. Numerical and theoretical considerations supported by experimental data provide evidence that we can use the vane shear test to obtain the undrained strength of a sample tested under simple shear conditions at a normal stress equal to the horizontal effective stress at the given depth. Consequently, it is argued that there is no need to correct the field vane undrained strength to obtain the mobilized strength for embankment stability calculations, provided that soil strength is normalized to the normal effective stress acting on the slip surface and rate effects are properly considered. We further show that the standard Tresca failure criterion, albeit simplistic, will provide reasonable estimates of the mobilized strength if properly calibrated against field vane tests.

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Calibration of Failure Criteria for Additively Manufactured Metallic Materials

Materials ◽

10.3390/ma14133442 ◽

2021 ◽

Vol 14 (13) ◽

pp. 3442

Author(s):

Grzegorz Socha

Keyword(s):

Failure Criterion ◽

Failure Strain ◽

Pure Shear ◽

Ductile Failure ◽

Failure Criteria ◽

Calibration Procedure ◽

Metallic Materials ◽

Ductile Materials ◽

Failure Models

A new version of failure criterion for additively manufactured materials, together with simple and accurate calibration procedures, is proposed and experimentally verified in this paper. The proposition is based on void growth-based ductile failure models. The failure criterion for ductile materials proposed by Hancock–Mackenzie was calibrated using simple methods and accessories. The calibration procedure allows the determination of failure strain under pure shear. The method is accurate and simple due to the fact that it prevents strain localization disturbing stress distribution at the failure zone. The original criterion was modified to better suit the deformation behavior of additively manufactured materials. Examples of calibration of the original and modified failure criteria for additively manufactured 316L alloy steel is also given in this paper, along with analyses of the obtained results.

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