scholarly journals Determination and Validation of Residual Stresses in CFRP/Metal Hybrid Components Using the Incremental Hole Drilling Method

2020 ◽  
Vol 4 (3) ◽  
pp. 143
Author(s):  
Tao Wu ◽  
Steffen R. Tinkloh ◽  
Thomas Tröster ◽  
Wolfgang Zinn ◽  
Thomas Niendorf
Keyword(s):  
Residual Stresses ◽  
Hybrid Materials ◽  
Strain Gauge ◽  
Bending Test ◽  
Orthotropic Materials ◽  
Hole Drilling ◽  
Metallic Component ◽  
Hole Drilling Method ◽  
Incremental Hole Drilling ◽  
Drilling Method

Lightweight materials contribute to an efficient decrease in fuel consumption in the automotive and aircraft industries. Hybrid components made of metal and carbon fiber-reinforced plastics (CFRP) have a high potential in lightweight applications due to their high strength-to-weight ratio. For cost-effective processing of hybrid materials, advanced manufacturing processes such as the prepreg-press-technology have been developed, in which the bonding between a metallic component and a fiber compound is exclusively realized in the forming process. However, upon processing of these hybrid components at elevated temperature, the difference in thermal expansion coefficients of the two materials leads to the formation of tensile residual stresses upon cooling. It is well known that these tensile residual stresses can be detrimentally effective with respect to the durability of a hybrid component. The objective of this work is to accurately measure and analyze residual stresses in hybrid components made of unidirectional CFRP and steel through the incremental hole drilling method. Within this study, the evaluation formalism for orthotropic materials is employed for measuring non-uniform residual stresses in hybrid materials. In order to improve the measurement accuracy, a customized strain gauge with eight grids is employed and a drilling increment size of only 20 µm is utilized. The influence of the angle between the strain gauge rosette and the fiber direction on the evaluation of the residual stresses is investigated. In order to evaluate the reliability of the results determined, a bending test applying a well-defined load is carried out. By direct comparison of the experimentally determined stresses and stress values calculated by the finite element method, the applicability of the hole drilling method for robust determination of residual stresses in CFRP/metal hybrid components is finally validated.

scholarly journals The Effect of Specimen Size on Residual Stresses in Friction Stir Welded Aluminum Components

2014 ◽  
Vol 996 ◽  
pp. 445-450 ◽  
Author(s):  
Wulf Pfeiffer ◽  
Eduard Reisacher ◽  
Michael Windisch ◽  
Markus Kahnert
Keyword(s):  
Residual Stresses ◽  
Specimen Size ◽  
Hole Drilling ◽  
X Ray Diffraction ◽  
X Ray ◽  
Friction Stir ◽  
Metal Parts ◽  
Hole Drilling Method ◽  
Incremental Hole Drilling ◽  
Drilling Method

Friction stir welding (FSW) is a well-known technique which allows joining of metal parts without severe distortion. Because FSW involves less heat input relative to conventional welding, it may be assumed that cutting specimens from larger friction stir welded components results in a negligible redistribution of residual stresses. The aim of the investigations was to verify these assumptions for a welded aluminum plate and a circumferentially-welded aluminum cylinder. Strain gage measurements, X-ray diffraction and the incremental hole drilling method were used.

scholarly journals Influence of Hydrothermal Ageing on the Residual Stresses and Mechanical Behavior of Carbon/Epoxy Composite Laminates

2014 ◽  
Vol 996 ◽  
pp. 958-963
Author(s):  
Zhong Meng Wen ◽  
Xiao Lu Gong
Keyword(s):  
Residual Stresses ◽  
Composite Laminates ◽  
Epoxy Composite ◽  
Hydrothermal Condition ◽  
Hole Drilling ◽  
Mechanical Behaviors ◽  
Hole Drilling Method ◽  
Incremental Hole Drilling ◽  
Drilling Method ◽  
The Relationship

In this work, the residual stresses for composite laminates [02/θ2]S determined by means of the incremental hole-drilling method with a formula to express the relationship between the residual stresses and the relaxed strains around the drilled hole. Then the ageing tests related to hydrothermal condition are carried out to analyze the influence on the residual stress redistributions and also on the mechanical behaviors of the carbon/epoxy laminates.

Study of Residual Stress Distribution by a Combined Method of Moire´ Interferometry and Incremental Hole Drilling, Part I: Theory

1998 ◽  
Vol 65 (4) ◽  
pp. 837-843 ◽  
Author(s):  
Zhu Wu ◽  
Jian Lu ◽  
Bongtae Han
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Plane Surface ◽  
Moiré Interferometry ◽  
Hole Drilling ◽  
Moire Interferometry ◽  
Hole Drilling Method ◽  
Surface Displacements ◽  
Incremental Hole Drilling ◽  
Drilling Method

A new method combining Moire´ interferometry and the incremental hole-drilling method is developed to determine both uniform and nonuniform residual stress distribution in depth. The study is reported in two parts. In this first part, the theoretical development of the moire´ interferometry hole-drilling method is presented. The relationship between the in-plane surface displacements produced by introducing a blind hole and the corresponding residual stresses is established by employing the existing theoretical solution containing a set of undetermined coefficients. The coefficients are calibrated by the three-dimensional finite element method and they are processed nondimensionally for general use. The whole field in-plane surface displacements data Ux and Uy produced by the relaxation of residual stresses are obtained from moire´ interferometry after each increment of hole drilling. The high signal-to-noise ratio provided by moire´ interferometry allows accurate determination of fringe orders near the hole boundary which is essential for enhancing fidelity of residual stress determination. The experimental procedure to determine the signs of residual stresses is described and the accuracy of the method is also discussed.

scholarly journals Application of the Incremental Hole-Drilling Method for the Determination of Residual Stresses in Glass-Fiber Reinforced Composites

2014 ◽  
Vol 996 ◽  
pp. 262-268
Author(s):  
Frank Schweizer ◽  
Marius Dickele ◽  
Michael Luke
Keyword(s):  
Residual Stresses ◽  
Glass Fiber ◽  
Fiber Reinforced Composites ◽  
Hole Drilling ◽  
Reinforced Composites ◽  
Fiber Reinforced ◽  
Hole Drilling Method ◽  
Glass Fiber Reinforced ◽  
Incremental Hole Drilling ◽  
Drilling Method

The incremental hole-drilling method was adapted for the measurement of residual stresses in polymer based composite materials. The parameters of the hole drilling process and the strain measurement in non-reinforced and 70 weight-percent glass-fiber-reinforced polypropylene were investigated. Calibration coefficients for the calculation of the residual stresses in the orthotropic material systems were determined by Finite Element Analysis. By means of application of the method to unidirectional and cross-ply glass-fiber reinforced composites the residual stresses, maximum measurable depths and measurement uncertainties could be derived.

Influence of Residual Stresses on the Damage of Composite Laminates under Tensile Loading

2015 ◽  
Vol 784 ◽  
pp. 361-368
Author(s):  
Zhong Meng Wen ◽  
Xiao Lu Gong
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Composite Laminates ◽  
Tensile Loading ◽  
Hole Drilling ◽  
Acoustic Emission Technique ◽  
Hole Drilling Method ◽  
Incremental Hole Drilling ◽  
Drilling Method

This work investigates the effect of residual stresses on the damage of composite laminate. The incremental hole-drilling method is applied to determine residual stresses in composite laminates [02/θ2]s and then acoustic emission technique is used for the identification of damage appearance during the tensile testing. The samples with different residual stress distribution are prepared through curing and post curing in order to study the role of residual stress on the damage of composite laminates. Besides the experimental method, the theoretical approach is applied to illustrate the role of residual stress on the damage of composite laminates.

scholarly journals The Effect of Fiber Waviness on the Residual Stress State and Its Prediction by the Hole Drilling Method in Fiber Metal Laminates: A Global-Local Finite Element Analysis

Metals ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 156
Author(s):  
Steffen Tinkloh ◽  
Tao Wu ◽  
Thomas Tröster ◽  
Thomas Niendorf
Keyword(s):  
Residual Stress ◽  
Stress State ◽  
Residual Stresses ◽  
Global Model ◽  
Hole Drilling ◽  
Fiber Waviness ◽  
Hole Drilling Method ◽  
Residual Stress State ◽  
Incremental Hole Drilling ◽  
Drilling Method

In this paper, fiber waviness, as one of the most frequently occurring defects in fiber reinforced composites, is numerically investigated with regard to the formation of residual stresses in fiber metal laminates. Furthermore, the prediction of the residual stress state in the thickness direction by means of the simulated hole drilling method is studied. To this regard, a global-local finite element analysis based on the submodel technique is presented. The submodel technique essentially consists of two governing steps: In the first step, a global model is first utilized to calculate and analyze the residual stress distribution and deformation in the intrinsically joined hybrid structure. Effective cure-dependent thermo–elastic properties predicted by a numerical homogenization procedure were used to simulate the curing-process and analyze the residual stresses state. However, the dimension of the intrinsically manufactured hybrid plate is large compared to the diameter of the drilled hole (2 mm), so that a local model is necessary, which provides only a geometric partial portion of the global model. The local model takes the global stress state into account and is subsequently used to simulate the incremental hole drilling method with a refined mesh discretization. The production-related fiber waviness is modeled by an element-wise orientation approximating a sinus function. In order to validate the global-local modeling approach, a comparison between numerical results and experimental data from literature is presented. The comparison between global residual stress state (global model) and the simulated hole drilling method (local model) is used to assess the applicability and reliability of the hole drilling method in case of fiber waviness. It is found that an in-plane fiber waviness leads to a rather low variance of residual stresses over thickness. In case of an out-of-plane fiber waviness, oscillating residual stress fields occur over the entire thickness along the fiber direction. Moreover, the current limits of the incremental hole drilling method could be pointed out by the presented investigations. It is seen that the simulated results of the incremental hole drilling method are sensitive to waviness, even if the amplitude-wavelength-ratio is small. Without further adjustment of the calibration coefficients the oscillating stress and strain fields lead, in particular fiber waviness in thickness direction, to unreliable predictions. For the experimental application it can be concluded that the specimens have to be carefully examined with regard to fiber waviness.

Data Management for the Evaluation of Residual Stresses by the Incremental Hole-Drilling Method

1994 ◽  
Vol 116 (4) ◽  
pp. 561-566 ◽  
Author(s):  
Dario Vangi
Keyword(s):  
Residual Stresses ◽  
Measurement Errors ◽  
Stress Measurement ◽  
Hole Drilling ◽  
Hole Drilling Method ◽  
Incremental Hole Drilling ◽  
Drilling Method ◽  
Experimental Errors ◽  
Thickness Variations ◽  
Stress Variations

The semidestructive incremental hole-drilling method commonly used to evaluate residual stresses is exceedingly sensitive to experimental errors, with sensitivity increasing as hole depth increases. To determine stress variations through the engine thickness, it is necessary to use accurate drilling methods, as well as suitable mathematical models and procedures to minimize the errors associated with residual stress measurement. This work examines the effects of measurement errors on the evaluation of residual stresses with the integral method. An enhanced procedure for managing the experimental data is proposed that allows evaluation of the residual stresses with thickness variations.

Investigation of Residual Stresses in Flame Sprayed Ni-Based Wear Resistant Coatings by the Hole-Drilling and X-Ray Methods

2013 ◽  
Vol 768-769 ◽  
pp. 144-149 ◽  
Author(s):  
Alexander Ryabchikov ◽  
Harri Lille ◽  
Renno Reitsnik ◽  
Stanislav Toropov ◽  
Andrei Surženkov ◽  
...  
Keyword(s):  
Residual Stresses ◽  
Hole Drilling ◽  
Ray Method ◽  
X Ray ◽  
Wear Resistant Coatings ◽  
Hole Drilling Method ◽  
Incremental Hole Drilling ◽  
Hard Metals ◽  
Drilling Method ◽  
Main Components

The present investigation was carried out in order to determine residual stresses inNi-based self-fluxing alloy based high velocity oxy-fuel (HVOF) coatings with different wearresistant additives. The main components of the alloy were Ni, Cr, Si and B. To increase the wearresistance of self-fluxing NiCrSiB alloy based coatings, different ceramics and hard metals(WC-Co, TiC-NiMo and Cr2C3-Ni) were added. Residual stresses were measured by the holedrillingmethod and the X-ray method. The incremental hole-drilling technique combined with theintegral method was applied. This combined method allows to analyse non-uniform throughthicknessresidual stresses. The results obtained with the incremental hole-drilling method indicatethat through-thickness residual stress distribution is non-uniform. The determined residual stresseswere tensile on the surface of the coating and became compressive toward the interface.The values of the modulus of elasticity and microhardness of the coatings were obtained byinstrumented indentation. The microstructures of the studied coatings were investigated with theSEM technique.

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