A novel model of Z-pin insertion in prepreg based on fracture mechanics

2021 ◽  
pp. 095440542110144
Author(s):  
Guobiao Ji ◽  
Liang Cheng ◽  
Shaohua Fei ◽  
Jiangxiong Li ◽  
Yinglin Ke
Keyword(s):  
Fracture Toughness ◽  
Fracture Mechanics ◽  
Analytical Model ◽  
Model Parameters ◽  
Force Model ◽  
Fe Model ◽  
Cohesive Elements ◽  
Fe Method ◽  
Insertion Force ◽  
Mechanics Model

Through-thickness reinforcement is a promising solution to the problem of delamination susceptibility in laminated composites. Modeling Z-pin–prepreg interaction is essential for accurate robotics-assisted Z-pin insertion. In this paper, a novel Z-pin insertion force model combining the classical cohesive finite element (FE) method with a dynamic analytical fracture mechanics model is proposed. The velocity-dependent cohesive elements, in which the fracture toughness is provided by the analytical model, are implemented in Z-pin insertion FE model to predict the crack initiation and propagation. Then Z-pin insertion experiments are performed on prepreg sample with metallic Z-pins at different velocities to identify the analytical model parameters and validate the simulation predictions offered by the model. Dynamics of Z-pin interaction with inhomogeneous prepreg is described and the effects of insertion velocity on prepreg contact force are studied. Results show that the force model agrees well with experiments and the fracture toughness rises with the increasing Z-pin insertion velocity.

Fracture Mechanics Model of Needle Cutting Tissue

2015 ◽  
Vol 138 (1) ◽  
Author(s):  
Andrew C. Barnett ◽  
Yuan-Shin Lee ◽  
Jason Z. Moore
Keyword(s):  
Fracture Toughness ◽  
Fracture Mechanics ◽  
Shear Modulus ◽  
Friction Force ◽  
Ex Vivo ◽  
Strain Curve ◽  
Needle Insertion ◽  
Force Model ◽  
Insertion Force ◽  
Needle Insertion Force

This work develops a needle insertion force model based on fracture mechanics, which incorporates the fracture toughness, shear modulus, and friction force of the needle and tissue. Ex vivo tissue experiments were performed to determine these mechanical tissue properties. A double insertion of the needle into the tissue was utilized to determine the fracture toughness. The shear modulus was found by applying an Ogden fit to the stress–strain curve of the tissue achieved through tension experiments. The frictional force was measured by inserting the needle through precut tissue. Results show that the force model predicts within 0.2 N of experimental needle insertion force and the fracture toughness is primarily affected by the needle diameter and needle edge geometry. On average, the tearing force was found to account for 61% of the total insertion force, the spreading force to account for 18%, and the friction force to account for the remaining 21%.

Needle Insertion Force Model for Haptic Simulation

2015 ◽  
Author(s):  
Adam Gordon ◽  
Inki Kim ◽  
Andrew C. Barnett ◽  
Jason Z. Moore
Keyword(s):  
Force Feedback ◽  
Needle Insertion ◽  
Model Parameters ◽  
Force Model ◽  
Medical Procedures ◽  
Insertion Force ◽  
Clinical Scenarios ◽  
Needle Insertion Force ◽  
Haptic Simulation ◽  
Simulation Systems

Percutaneous medical procedures rely upon clinicians performing precise needle insertion in soft tissue. The utility of haptic simulation systems in training clinicians for these procedures is highly dependent upon the ability to render accurate insertion force feedback. This paper presents a piecewise mathematical model for insertion force that does not require tissue material properties, detailed mechanical approximations, or complex computations. With manipulation of model parameters, a wide variety of insertion tasks and clinical scenarios can be modeled. Through needle insertion experiments and parameter estimation, this model was demonstrated to replicate the insertion forces associated with a variety of needle and tissue types. In 11 of 12 needle and tissue combinations tested, the model replicated the insertion force with an average absolute mean error of less than 0.065 N.

scholarly journals Experimental fracture and mechanical properties of Antarctic ice: preliminary results

1996 ◽  
Vol 23 ◽  
pp. 284-292 ◽  
Author(s):  
M. A. Rist ◽  
P. R. Sammonds ◽  
S. A. F. Murrell ◽  
P. G. Meredith ◽  
H. Oerter ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Fracture Mechanics ◽  
Crack Nucleation ◽  
Ice Core ◽  
Critical Stress Intensity Factor ◽  
Ice Shelf ◽  
Small Surface ◽  
Preliminary Results ◽  
Mechanics Model ◽  
Apparent Fracture Toughness

An experimental study of the fracture mechanics and rheology of ice from the Ronne Ice Shelf, Antarctica, is currently being undertaken. The apparent critical stress-intensity factor (or apparent fracture toughness,KQ) for crack propagation has been measured using a three-point bend method for inducing crack growth perpendicular to the axis of cylindrical ice-core specimens. Tensile crack nucleation under applied uniaxial compressive stress has also been evaluated. Both methods have allowed a profile of ice elastic and fracture properties with depth through the ice shelf to be constructed. Preliminary results indicate that the measured elastic modulus increases with depth through the firn and upper meteoric ice before reaching a constant value in the deeper, dense meteoric and basal marine ice. The resistance to fracture, as measured by changes in apparent fracture toughness and crack-nucleation stress, increases with depth right through the firn and meteoric ice layers. A simple fracture mechanics model applied to the Ronne Ice Shelf indicates that crevasses form from small surface cracks, less than 40 cm deep, which quickly grow to depths of 40–60m and then remain stable.

scholarly journals Experimental fracture and mechanical properties of Antarctic ice: preliminary results

1996 ◽  
Vol 23 ◽  
pp. 284-292 ◽  
Author(s):  
M. A. Rist ◽  
P. R. Sammonds ◽  
S. A. F. Murrell ◽  
P. G. Meredith ◽  
H. Oerter ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Fracture Mechanics ◽  
Crack Nucleation ◽  
Ice Core ◽  
Critical Stress Intensity Factor ◽  
Ice Shelf ◽  
Small Surface ◽  
Preliminary Results ◽  
Mechanics Model ◽  
Apparent Fracture Toughness

An experimental study of the fracture mechanics and rheology of ice from the Ronne Ice Shelf, Antarctica, is currently being undertaken. The apparent critical stress-intensity factor (or apparent fracture toughness, K Q) for crack propagation has been measured using a three-point bend method for inducing crack growth perpendicular to the axis of cylindrical ice-core specimens. Tensile crack nucleation under applied uniaxial compressive stress has also been evaluated. Both methods have allowed a profile of ice elastic and fracture properties with depth through the ice shelf to be constructed. Preliminary results indicate that the measured elastic modulus increases with depth through the firn and upper meteoric ice before reaching a constant value in the deeper, dense meteoric and basal marine ice. The resistance to fracture, as measured by changes in apparent fracture toughness and crack-nucleation stress, increases with depth right through the firn and meteoric ice layers. A simple fracture mechanics model applied to the Ronne Ice Shelf indicates that crevasses form from small surface cracks, less than 40 cm deep, which quickly grow to depths of 40–60m and then remain stable.

scholarly journals Fracture Toughness Analysis of Aluminum (Al) Foil and Its Adhesion with Low-Density Polyethylene (LPDE) in the Packing Industry

Coatings ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1079
Author(s):  
Umer Sharif ◽  
Beibei Sun ◽  
Md Shafiqul Islam ◽  
Kashif Majeed ◽  
Dauda Sh. Ibrahim ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Aluminum Foil ◽  
Material Model ◽  
Extensive Study ◽  
Low Density Polyethylene ◽  
Model Parameters ◽  
Fe Model ◽  
Low Density ◽  
Yield Model ◽  
Damage Initiation

Liquid food packages consist of various polymers films, which are bonded together with Aluminum foil (Al-foil) using adhesion or by direct heat. The main aim of this research was to define important material properties such as fracture toughness and some FE-simulation material model parameters such as damage initiation, damage evolution, and the adhesion between Al-foil and low-density polyethylene (LDPE) film. This investigation is based on both physical experiments and FE simulations in ABAQUS with and without initial cracks of different lengths for comparison purposes. The final FE model in ABAQUS was used to compare the numerical input parameters in an extensive study with the ambition to investigate the materials’ parameters in cases with or without adhesion between laminates. Finally, the relation between the theoretical and experimental results for Al-foil using linear elastic fracture mechanics and modified strip yield model were shown, and the fracture toughness was calculated for two different thicknesses of Al-foil.

Reliability of Carbon Coated Optical Fibers

2005 ◽  
Author(s):  
Srinath S. Chakravarthy ◽  
Wilson K. S. Chiu
Keyword(s):  
Fracture Toughness ◽  
Residual Stress ◽  
Fracture Mechanics ◽  
Optical Fibers ◽  
Critical Role ◽  
Carbon Film ◽  
Mechanics Model ◽  
Carbon Coated ◽  
Good Agreement ◽  
Deposition Conditions

The inert strength of carbon coated optical fibers has been observed to be less than that standard optical fibers. The fracture toughness of the carbon film and the residual stress in the film play a critical role in determining the strength of the carbon coated optical fibers. The fracture toughness and the residual stress in the film were measured for a variety of deposition conditions. A recently developed fracture mechanics model was used to predict the failure of carbon coated optical fibers. Model based strength predictions were compared to experimentally measured values. The prediction was found to be in good agreement with the measured values.

Representation of bolted joints in a structure using finite element modelling and model updating

2020 ◽  
Vol 14 (3) ◽  
pp. 7141-7151 ◽  
Author(s):  
R. Omar ◽  
M. N. Abdul Rani ◽  
M. A. Yunus
Keyword(s):  
Finite Element ◽  
Dynamic Behaviour ◽  
Model Updating ◽  
Complex Structure ◽  
Bolted Joints ◽  
Model Parameters ◽  
Fe Model ◽  
Bolted Joint ◽  
Fe Modelling ◽  
Joint Structure

Efficient and accurate finite element (FE) modelling of bolted joints is essential for increasing confidence in the investigation of structural vibrations. However, modelling of bolted joints for the investigation is often found to be very challenging. This paper proposes an appropriate FE representation of bolted joints for the prediction of the dynamic behaviour of a bolted joint structure. Two different FE models of the bolted joint structure with two different FE element connectors, which are CBEAM and CBUSH, representing the bolted joints are developed. Modal updating is used to correlate the two FE models with the experimental model. The dynamic behaviour of the two FE models is compared with experimental modal analysis to evaluate and determine the most appropriate FE model of the bolted joint structure. The comparison reveals that the CBUSH element connectors based FE model has a greater capability in representing the bolted joints with 86 percent accuracy and greater efficiency in updating the model parameters. The proposed modelling technique will be useful in the modelling of a complex structure with a large number of bolted joints.

Development and analysis of composite overwrapped pressure vessels for hydrogen storage

2021 ◽  
pp. 002199832110335
Author(s):  
Osman Kartav ◽  
Serkan Kangal ◽  
Kutay Yücetürk ◽  
Metin Tanoğlu ◽  
Engin Aktaş ◽  
...  
Keyword(s):  
Hydrogen Storage ◽  
Damage Model ◽  
Pressure Vessels ◽  
Filament Winding ◽  
Burst Pressure ◽  
Fe Model ◽  
Fe Method ◽  
Liner Material ◽  
Mechanical Performances ◽  
Metallic Liner

In this study, composite overwrapped pressure vessels (COPVs) for high-pressure hydrogen storage were designed, modeled by finite element (FE) method, manufactured by filament winding technique and tested for burst pressure. Aluminum 6061-T6 was selected as a metallic liner material. Epoxy impregnated carbon filaments were overwrapped over the liner with a winding angle of ±14° to obtain fully overwrapped composite reinforced vessels with non-identical front and back dome layers. The COPVs were loaded with increasing internal pressure up to the burst pressure level. During loading, deformation of the vessels was measured locally with strain gauges. The mechanical performances of COPVs designed with various number of helical, hoop and doily layers were investigated by both experimental and numerical methods. In numerical method, FE analysis containing a simple progressive damage model available in ANSYS software package for the composite section was performed. The results revealed that the FE model provides a good correlation as compared to experimental strain results for the developed COPVs. The burst pressure test results showed that integration of doily layers to the filament winding process resulted with an improvement of the COPVs performance.

Linear translaminar fracture characterization of additive manufactured continuous carbon fiber reinforced thermoplastic

2021 ◽  
pp. 089270572110214
Author(s):  
Weiller M Lamin ◽  
Flávio LS Bussamra ◽  
Rafael TL Ferreira ◽  
Rita CM Sales ◽  
José E Baldo
Keyword(s):  
Fracture Toughness ◽  
Carbon Fiber ◽  
Fracture Mechanics ◽  
Image Correlation ◽  
Fiber Reinforced ◽  
Fused Filament Fabrication ◽  
Critical Energy Release Rate ◽  
Linear Elastic ◽  
Continuous Carbon Fiber ◽  
Carbon Fiber Reinforced

This work presents the experimental determination of fracture mechanics parameters of composite specimens manufactured by fused filament fabrication (FFF) with continuous carbon fiber reinforced thermoplastic filaments, based on Linear Elastic Fracture Mechanics (LEFM). The critical mode I translaminar fracture toughness (KIc) and the critical energy release rate (GIc) are found for unidirectional and cross-ply laminates. The specimens were submitted to quasi-static tensile testing. Digital Image Correlation (DIC) is used to find the stress field. The stress fields around the crack tip are compared to linear elastic finite element simulations. The results demonstrate the magnitude of fracture toughness is in the same range as for polymers and some metals, depending on lay-up configuration. Besides, fractographic analyses show some typical features as river lines, fiber impression, fiber pulls-out and porosity aspects.

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