Experimental Research on Failure Mechanism of a CVI-Fabricated Ceramic Matrix Composite under Compression

2006 ◽  
Vol 326-328 ◽  
pp. 1841-1844 ◽  
Author(s):  
Guo Yang Guan ◽  
Gui Qiong Jiao ◽  
Tao Huang
Keyword(s):  
Failure Mechanism ◽  
Experimental Research ◽  
Fracture Mechanism ◽  
Failure Modes ◽  
Ceramic Matrix Composite ◽  
Ceramic Matrix ◽  
Mechanical Tests ◽  
Strength Prediction ◽  
Compressive Behavior ◽  
Linear Feature

Mechanical tests have been conducted to understand compressive behavior of a plain weave C/SiC composite, especially to investigate the failure mechanism. The stress-strain curves of this composite show linear feature in compression. The specimens fail along a flat plane 13°~15° to the weave plane, running across four typical regions in the bulk: weft bundle, warp/weft interface, warp bundle, and inter-ply. According to the observed fracture route, four basic failure modes are schematically presented. Cracks form and develop in these areas along fiber/matrix interphase or within matrix, depending on the strength competition between interphase and matrix. The fracture mechanism reveals dependence of compress strength on matrix abundance between and within bundles. Based on the failure modes new method for compress strength prediction can be further investigated.

The Application of Ceramic Matrix Composite to Low Pressure Turbine Blade

2016 ◽  
Author(s):  
Fumiaki Watanabe ◽  
Takeshi Nakamura ◽  
Ken-ichi Shinohara
Keyword(s):  
Centrifugal Force ◽  
Failure Modes ◽  
Ceramic Matrix Composite ◽  
Ceramic Matrix ◽  
Low Pressure ◽  
Screening Tests ◽  
Low Pressure Turbine ◽  
Load Tests ◽  
Tip Shroud ◽  
Block Approach

The structural reliability of composite parts for aircraft is established through the “building block” approach, which is a series of tests that are conducted using specimens of various levels of complexity. In this approach, the failure modes and criteria are validated step by step with tests and analysis at coupon, element, sub-component, and component levels. IHI is developing ceramic matrix composite (CMC) components for aircraft engines to realize performance improvement and weight reduction. We conducted the concept design of CMC low pressure turbine (LPT) blade with the building block approach. In this paper, we present the processes and results of the design, which was supported by a series of tests. Typical low pressure turbine blade has dovetail, airfoil and tip shroud. Each element has different function and characteristic shape. In order to select the configuration of CMC LPT blade, we conducted screening tests for each element. The function of dovetail is to sustain the connection with blade and disk against centrifugal force. The failure modes and strength of dovetail elements were examined by static load tests and cyclic load tests. The configuration of airfoil was selected by modal tests. The function of tip shroud is forming gas passage and reducing the leakage flow, therefore this portion needs to sustain the shape against the centrifugal force and the rubbing force. The feasibility of tip shroud was verified by spin tests and rubbing tests. The initial CMC LPT blades were designed as combination of the selected elements by these screening tests. Prototype parts were made and tested to check the manufacturability and the structural feasibility. The static strength to the centrifugal force was examined by spin test. The durability to vibration was examined by HCF test.

Investigation of Moisture Sensitivity Related Failure Mechanism of Quad Flat No-Lead (QFN) Packages

2008 ◽  
Author(s):  
Minshu Zhang ◽  
S. W. Ricky Lee
Keyword(s):  
Finite Element ◽  
Failure Mechanism ◽  
Material Properties ◽  
Test Performance ◽  
Interfacial Adhesion ◽  
Failure Modes ◽  
Material Selection ◽  
Mechanical Tests ◽  
Element Analysis ◽  
Moisture Sensitivity

Interfacial delamination is a long existing problem in the moisture preconditioning process and reflow. The failure is caused by the competition between interfacial strength and hygrothermal stress. Many simulations based on the finite element model have been applied to study the failure mechanism of this phenomenon. However, the difficulty in obtaining material properties of mini-size packages, the lack of experiment investigation of interfacial adhesion and the less-understood moisture analysis will always bring many challenges to simulations. To avoid the above issues, dummy QFN packages were fabricated as the test vehicle for the investigation of the moisture related failure. The major advantage of using dummy packages is that all material properties could be traced and all geometric parameters could be determined without ambiguities. With everything under control, failure modes could be generated within expectation. This would provide a good experiment comparison for future finite element analysis. In this study, several experiment procedures were implemented to establish the relationship between material selection and moisture sensitivity level (MSL) test performance. They were package fabrication, mechanical tests for interfacial adhesion, C-SAM and cross-section inspections. Based on the experimental results, features of the moisture related failure mechanism are presented in this paper.

Experimental Research on the Behavior of Adhesive Reinforcement under Pullout Load

2014 ◽  
Vol 501-504 ◽  
pp. 1027-1031 ◽  
Author(s):  
Li Zhong Shi ◽  
Jian Rong Zhang
Keyword(s):  
Failure Mechanism ◽  
Ultimate Strength ◽  
Experimental Research ◽  
Failure Modes ◽  
Tensile Load ◽  
Experimental Results ◽  
Design Suggestion ◽  
Pullout Load ◽  
Adhesive Anchors

This paper reports the experimental results of 5 groups of 18 adhesive reinforcement bars in concrete under pullout load. Through observing the experiment process, measuring the characteristic loads, and analyzing the failure mechanism, the behavior of adhesive reinforcement under tensile load is studied and described. Based on the tests and previous findings of other researchers, the five failure modes observed for adhesive anchors can be summarized.The formula to calculate the ultimate strength and some design suggestion are also presented.

Effect of Interfacial Treatment Process on the Microstructure and Properties of Cf/SiC Ceramic Matrix Composites

2012 ◽  
Vol 519 ◽  
pp. 277-280 ◽  
Author(s):  
Xiu Qian Li ◽  
Hai Peng Qiu ◽  
Jian Jiao ◽  
Jing Hua Luo ◽  
Yu Wang
Keyword(s):  
Fracture Toughness ◽  
Treatment Process ◽  
Ceramic Matrix Composite ◽  
Ceramic Matrix Composites ◽  
Ceramic Matrix ◽  
Mechanical Tests ◽  
Bending Test ◽  
High Temperature Treatment ◽  
Matrix Composites ◽  
Sic Ceramic

Abstract. This paper investigated the Cf/SiC ceramic matrix composites. By utilizing different interfacial treatment processes to prepare carbon-fiber preform, the preform was then densified by infiltration and pyrolysis(PIP) with polycarbosilan/xylene solution as precursor, and the Cf/SiC ceramic matrix composite specimens were fabricated. Mechanical tests such as bending test and fracture toughness were performed for Cf/SiC samples. The results show that the interfacial bonding strength in the sample with high-temperature treatment process was improved due to removing surface sizing. The samples which were treated up to 1400°C exhibited the highest three-point flexural strength, up to 595MPa; The samples which were treated up to 1400°C and deposited by pyrolytic carbon(PyC) coating shows the highest fracture toughness value which was 20.70MPa•m1/2.

scholarly journals Experimental Research on Reinforced Concrete Columns Strengthened with Steel Jacket and Concrete Infill

2021 ◽  
Vol 11 (9) ◽  
pp. 4043
Author(s):  
Aleksandar Landović ◽  
Miroslav Bešević
Keyword(s):  
Compressive Strength ◽  
Reinforced Concrete ◽  
Cross Section ◽  
Experimental Research ◽  
Failure Modes ◽  
Steel Tube ◽  
Rc Columns ◽  
Rc Column ◽  
Steel Jacket ◽  
Ductile Behavior

Experimental research on axially compressed columns made from reinforced concrete (RC) and RC columns strengthened with a steel jacket and additional fill concrete is presented in this paper. A premade squared cross-section RC column was placed inside a steel tube, and then the space between the column and the tube was filled with additional concrete. A total of fourteen stub axially compressed columns, including nine strengthened specimens and five plain reinforced concrete specimens, were experimentally tested. The main parameter that was varied in the experiment was the compressive strength of the filler concrete. Three different concrete compression strength classes were used. Test results showed that all three cross-section parts (the core column, the fill, and the steel jacket) worked together in the force-carrying process through all load levels, even if only the basic RC column was loaded. The strengthened columns exhibited pronounced ductile behavior compared to the plain RC columns. The influence of the test parameters on the axial compressive strength was investigated. In addition, the specimen failure modes, strain development, and load vs. deformation relations were registered. The applicability of three different design codes to predict the axial bearing capacity of the strengthened columns was also investigated.

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