Notched Strength Prediction and Verification of APC-2 Composite Laminates at Elevated Temperature

2009 ◽  
Vol 79-82 ◽  
pp. 1563-1566 ◽  
Author(s):  
Ming Hwa R. Jen ◽  
Yi Chun Sung ◽  
Yu Chung Tseng
Keyword(s):  
Experimental Data ◽  
Elevated Temperature ◽  
Composite Laminates ◽  
Elevated Temperatures ◽  
Characteristic Length ◽  
Tensile Tests ◽  
Stress Criterion ◽  
Static Tensile ◽  
Notched Strength ◽  
Good Agreement

The notched strength of AS-4/PEEK (APC-2) composite laminates with a central hole at elevated temperature was systematically studied by both analytical and empirical methods. First, the APC-2 cross-ply [0/90]4s panels were fabricated and cut into samples. Each sample was drilled a hole in the center with five kinds of diameters, such as d=0(unnotched), 1, 2, 3, and 4mm. Then, the samples were subjected to quasi-static tensile tests at elevated temperatures, including 25°C (RT), 75, 100, 125, 150 and 175°C, to measure their mechanical properties. The average values of received notched strength were affected significantly by stress concentration and high temperature. In analysis the prediction of residual strength by point stress criterion (PSC) was adopted first and found unsatisfactory due to at least 15% errors with experimental data. Then, the modified PSC was used with the varied characteristic length dependent on nature of material and specimen geometry. The predicted notched strengths by the modified PSC model were in very good agreement with experimental data. The predictive results were not only precisely validated, but extended to the application at elevated temperature.

Fatigue responses of cracked Ti/APC-2 nanocomposite laminates at elevated temperature

2019 ◽  
Vol 54 (13) ◽  
pp. 1705-1715
Author(s):  
MHR Jen ◽  
GT Kuo ◽  
YH Wu ◽  
YJ Chen
Keyword(s):  
Mechanical Properties ◽  
Elevated Temperature ◽  
Composite Laminates ◽  
Elevated Temperatures ◽  
Tensile Tests ◽  
Cyclic Tests ◽  
Constant Length ◽  
Nano Powder ◽  
Strength And Stiffness ◽  
Inclined Angle

The mechanical properties and fatigue responses of Ti/APC-2 neat and nanocomposites with inclined single-edged cracks due to tensile and cyclic tests at elevated temperature were investigated. Two types of composite laminates [Ti/(0/90)s/Ti] were fabricated with and without (W/WO) nanoparticles SiO2 of optimal 1 wt.%. The geometry and dimensions of specimens were L × W × t = 240 × 25 × 1.55 mm3. The cracks were of constant length 3 mm and width 0.3 mm. The inclined angles were 0°, 45°, and 60°. Both the tensile and cyclic tests were conducted at elevated temperatures 25℃ (RT), 100℃, 125℃, and 150℃. From the tensile tests we obtained the load vs. displacement curves for both types of laminates with varied inclinations at elevated temperatures. Next, we received the applied load vs. cycles curves for the same laminates with inclined cracks at the corresponding temperature due to cyclic tests. According to the experimental data of both tensile and cyclic tests the mechanical properties, such as strength, stiffness, and life, decreased as the temperature rises. The greater the inclined angles were, the greater the strength and stiffness were. Similarly, the fatigue life was in the same trend. However, the effect of inclined angle on mechanical properties was more strong than those of temperature. The mechanical properties of nanocomposite laminates were higher than those of neat composite laminates, but not significant. The main reason was that the enhancement of spreading nano-powder silica on the laminate interfaces did not effectively eliminate the stress intensity at the crack tip locally.

Springback Behavior of an Invar Sheet and Its Perforated Form

2006 ◽  
Vol 505-507 ◽  
pp. 781-786
Author(s):  
Yi Che Lee ◽  
Fuh Kuo Chen
Keyword(s):  
Experimental Data ◽  
Mechanical Properties ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Tensile Tests ◽  
Test Results ◽  
Bending Tests ◽  
Predicted Values ◽  
Springback Behavior ◽  
Good Agreement

The springback behavior of an invar sheet and its perforated form were examined in the present study. The mechanical properties for invar sheet and perforated invar-sheet at elevated temperatures were first obtained from tensile tests. The test results suggest that both invar sheet and perforated invar-sheet have favorable formability at temperature higher than 200oC. An analytical model was also established to predict the springback of the invar sheet and its perforated form under bending conditions at various elevated temperatures. In order to verify the predicted results, the V-bending tests were conducted for the invar sheet at various temperatures ranging from room temperature to 300. The experimental data indicate that the springback decreases with the rise in temperature for both invar sheet and perforated invar-sheet. The good agreement between the experimental data and the predicted values confirms the validity of the proposed theoretical model as well.

Experimental Investigation of Ti-6Al-4V with a Biaxial Tensile Test Setup at Elevated Temperature

2014 ◽  
Vol 622-623 ◽  
pp. 273-278 ◽  
Author(s):  
Marion Merklein ◽  
Sebastian Suttner ◽  
Adam Schaub
Keyword(s):  
Elevated Temperature ◽  
Elevated Temperatures ◽  
Tensile Tests ◽  
Advanced Materials ◽  
Uniaxial Tensile ◽  
Plastic Yielding ◽  
Characterization Methods ◽  
Specific Strength ◽  
Biaxial Tensile ◽  
Stress States

The requirement for products to reduce weight while maintaining strength is a major challenge to the development of new advanced materials. Especially in the field of human medicine or aviation and aeronautics new materials are needed to satisfy increasing demands. Therefore the titanium alloy Ti-6Al-4V with its high specific strength and an outstanding corrosion resistance is used for high and reliable performance in sheet metal forming processes as well as in medical applications. Due to a meaningful and accurate numerical process design and to improve the prediction accuracy of the numerical model, advanced material characterization methods are required. To expand the formability and to skillfully use the advantage of Ti-6Al-4V, forming processes are performed at elevated temperatures. Thus the investigation of plastic yielding at different stress states and at an elevated temperature of 400°C is presented in this paper. For this reason biaxial tensile tests with a cruciform shaped specimen are realized at 400°C in addition to uniaxial tensile tests. Moreover the beginning of plastic yielding is analyzed in the first quadrant of the stress space with regard to complex material modeling.

Experimental Study on the Mechanical Property and Forming Limit of Magnesium Sheet at Elevated Temperatures

2009 ◽  
Author(s):  
Y. Huang ◽  
J. Huang ◽  
J. Cao
Keyword(s):  
Elevated Temperature ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Strain Curve ◽  
Tensile Tests ◽  
Alloy Sheet ◽  
Dome Height ◽  
Forming Limit ◽  
Uniaxial Tensile ◽  
Magnesium Sheet

Magnesium alloy sheet has received increasing attention in automotive and aerospace industries. It is widely recognized that magnesium sheet has a poor formability at room temperature. While at elevated temperature, its formability can be dramatically improved. Most of work in the field has been working with the magnesium sheet after annealed around 350°C. In this paper, the as-received commercial magnesium sheet (AZ31B-H24) with thickness of 2mm has been experimentally studied without any special heat treatment. Uniaxial tensile tests at room temperature and elevated temperature were first conducted to have a better understanding of the material properties of magnesium sheet (AZ31B-H24). Then, limit dome height (LDH) tests were conducted to capture forming limits of magnesium sheet (AZ31B-H24) at elevated temperatures. An optical method has been introduced to obtain the stress-strain curve at elevated temperatures. Experimental results of the LDH tests were presented.

Sulfur Effects on High-Temperature Creep and Fracture Behavior of 25Cr35Ni-Nb Alloys

2013 ◽  
Author(s):  
Tao Chen ◽  
Xuedong Chen ◽  
Juan Ye ◽  
Xiyun Hao
Keyword(s):  
Elevated Temperature ◽  
Grain Boundaries ◽  
Fracture Behavior ◽  
Elevated Temperatures ◽  
Rupture Life ◽  
Local Stress ◽  
Tensile Tests ◽  
Creep Rupture ◽  
Scanning Electron Micrographs ◽  
Nucleation Sites

Centrifugal cast 25Cr35Ni-Nb alloy furnace tubes with different contents of S are selected to investigate effects of S addition on creep and fracture behavior. Rupture tests in air at 1100 °C and 17 MPa and slow rate tensile tests at 850 °C showed that the presence of S decreased the creep rupture life and elevated temperature ductility of 25Cr35Ni-Nb alloy obviously. Scanning electron micrographs (SEM) of the fracture and energy dispersive X-ray spectroscopy (EDS) analysis results indicated that S was the important element to control creep rupture life and elevated temperature ductility. S segregated to grain boundaries at elevated temperatures, blocky fine sulfide particles with smooth surface distribute on the grain boundaries. The presence of sulfides became effective nucleation sites for intergranular creep cavities. Micro cracks occurred by linking up cavities at elevated temperatures due to local stress concentration. Eventually, early failure happened.

High Strain Rate Tensile Behavior of Carbon Fiber Reinforced Aluminum Laminates

2005 ◽  
Author(s):  
Yuanxin Zhou ◽  
Pingwen Mao ◽  
Mohammad F. Uddin ◽  
Shaikh Jeelani
Keyword(s):  
Carbon Fiber ◽  
Strain Rate ◽  
Rate Sensitivity ◽  
Tensile Tests ◽  
Strain Rate Range ◽  
Fiber Reinforced ◽  
Stress Strain ◽  
Static Tensile ◽  
Carbon Fiber Reinforced ◽  
Good Agreement

In this paper, loading and loading-unloading tests of carbon fiber reinforced aluminum laminates (CRALL) have been carried out in a tensile impact apparatus, and quasi-static tensile tests have been performed on a MTS-810 machine. Complete stress-strain curves of composite in the strain rate range from 0.001–1200 1/s have been obtained. Experimental results show that CRALL composite is a strain rate sensitivity material, the tensile strength and failure strain both increased with increasing strain rate. A linear strain hardening model has been combined with Weibull distribution function to establish a constitutive equation for CRALL. The simulated stress-strain curves from model are in good agreement with the test data. The analysis of the model shows that the Weibull scale parameter, σ0, increased with increasing strain rate, but Weibull shape parameter, β, can be regarded as a constant.

Effect of transverse reinforcement on cracking of CFRP composite laminates under static and fatigue loads

2020 ◽  
Vol 54 (25) ◽  
pp. 3755-3766 ◽  
Author(s):  
Maciej Giżyński
Keyword(s):  
Composite Laminates ◽  
Crack Density ◽  
Tensile Tests ◽  
Fatigue Tests ◽  
Transverse Reinforcement ◽  
Damage Growth ◽  
Cfrp Laminates ◽  
Cfrp Composite ◽  
Static Tensile

Several CFRP laminates with various layups, possessing two distinctive forms of transverse reinforcement either UD 90° or fabric 0°/90°, were tested in both static and fatigue tests. All examined layups were considered to be used in the wingbox design of the multipurpose turboprop aircraft. In-situ microscopic observations were carried out during the tests. Static tensile tests allowed to find the strength of the laminas, stress, and strains at which cracks started to propagate, crack density during the test. The microscopic observations allowed to establish cracks’ growth paths. The first crack in laminates having fabric 0°/90° laminas usually was observed for higher stress and strain than in laminates with UD 90° laminas. Also, the later ones showed a tendency to significantly delaminate along the interface between UD 90° and UD 45° laminas. The fatigue test was carried out in order to find how to distinguish damage growth in both families of laminates that affects their fatigue life. As an outcome, S-N lines were determined. During the test the microscopic observations were made, which allowed to show crack and delamination growth during successive load cycles. The microscopic observations showed that cyclic loading leads to the fast growth of delaminations at the interface of fabric 0°/90°ply or UD 90° laminas.

Manufacturing and Mechanical Responses of Ti/APC-2 Nanocomposite Cross-Ply and Quasi-Isotropic Laminates at Elevated Temperature

2010 ◽  
Vol 150-151 ◽  
pp. 796-799
Author(s):  
Ming Hwa Jen ◽  
Che Kai Chang ◽  
Yi Chun Sung ◽  
Feng Chi Hsu
Keyword(s):  
Elevated Temperature ◽  
Stress Amplitude ◽  
Tensile Tests ◽  
Measured Data ◽  
Cyclic Tests ◽  
Mechanical Responses ◽  
Longitudinal Stiffness ◽  
Strength And Stiffness ◽  
To Receive ◽  
Good Agreement

Both Ti/APC-2 cross-ply and quasi-isotropic nanocomposite laminates were successfully fabricated. Basically, the tensile tests at elevated temperature were conducted to obtain the baseline data of mechanical properties, such as strength and stiffness. The results for both types of laminates of longitudinal stiffness predicted by the rule of mixtures (ROM) were in good agreement with experimental data, whilst, those ultimate strength predicted by ROM were lower than the measured data. Then, the tension-tension (T-T) constant stress amplitude cyclic tests were performed at elevated temperature to receive the S-N curves, fatigue strength and life. It is a surprise that almost no delaminations were observed in tensile and cyclic tests, even at elevated temperature and over a million cycles.

Fatigue Response of Hybrid Ti/APC-2 Nanocomposite Laminates with Single-Edged Cracks

2013 ◽  
Vol 592-593 ◽  
pp. 425-428
Author(s):  
Ming Hwa R. Jen ◽  
Che Kai Chang ◽  
Bo Cyuan Lin
Keyword(s):  
Mechanical Properties ◽  
Crack Length ◽  
Composite Laminates ◽  
Residual Life ◽  
Tensile Tests ◽  
Cyclic Tests ◽  
Paris Law ◽  
Modified Method ◽  
Longitudinal Stiffness ◽  
Static Tensile

The aims of this study are to fabricate Ti/APC-2 hybrid composite laminates with and without (W/WO) nanoparticles and investigate the mechanical properties of laminates with single-edged cracks due to both tensile and cyclic tests. The mechanical properties such as ultimate tensile strength and longitudinal stiffness of original composite laminates W/WO nanoparticles were first obtained from the static tensile tests. However, the load-displacement diagrams were plotted for the crack laminates. The constant stress amplitude tension-tension cyclic tests were conducted to receive the S-N curves and fatigue data. The ultimate strengths for both Ti/APC-2 composite laminates W/WO nanoparticles were very close at varied crack length. Ti/APC-2 cross-ply nanocomposite laminates had better fatigue resistance than that of laminates without nanoparticles. The longer the crack length is, the more their properties are reduced. Also, the values of fracture toughness of both hybrid cracked laminates W/WO nanoparticles were obtained by rule of mixtures and found acceptable. Finally, in predicting crack growth rate and residual life, instead of commonly used Paris Law for metals, the modified method was adopted for hybrid cracked laminates. The prediction is not satisfactorily acceptable, even if most results are in good agreement with empirical data.

Tensile and Fatigue Testings of Hybrid Al/APC-2 Nanocomposite Laminates at Elevated Temperature

2008 ◽  
Vol 47-50 ◽  
pp. 592-595 ◽  
Author(s):  
Ming Hwa R. Jen ◽  
Yi Chun Sung ◽  
Yin Da Lai
Keyword(s):  
Mechanical Properties ◽  
Elevated Temperature ◽  
Tensile Tests ◽  
Fatigue Tests ◽  
Thermoplastic Matrix ◽  
Longitudinal Stiffness ◽  
Hybrid Laminates ◽  
Static Tensile ◽  
Aluminum Alloy 2024 ◽  
Strength And Stiffness

To deal with the stringent operational demands the aerospace structural materials of light weight Aluminum alloy 2024 sheets and plies of carbon fibers reinforced thermoplastic matrix PEEK were used to sustain at least 80% of their mechanical properties at elevated temperature. The addition of nanoparticles SiO2 can enhance the composite laminate strength and stiffness. Also, Al 2024 sheets were treated by an anodic method of electroplating to increase surface roughness to achieve perfectly bonding with matrix PEEK. Then, the modified diaphragm curing process was adopted to make the innovative hybrid Al/APC-2 hybrid nanocomposite laminates. Next, both static tensile and fatigue tests were conducted at elevated temperature to obtain the mechanical properties, lives and failure mechanisms to verify the improved features of hybrid specimens. From tensile tests the mechanical properties of Al/APC-2 [4Al/0/±45/90/2Al]s hybrid laminates at elevated temperature were obtained. Although there is a big drop at 150°C, the reduction in strength from RT to 125°C is generally not significant. The longitudinal stiffness is almost unchanged at elevated temperature. After cyclic tension-tension (T-T) tests, the positions of received S-N curves go downwards as temperature rising. No delaminations were found in both tests. If the applied stress normalized by the ultimate strength at corresponding temperature, the normalized S-N curves are closer with some curve positions reversed. Significant improvement of manufacturing and enhancement of mechanical properties in hybrid laminates were achieved finally.

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