Mechanical Property of Glass Mat Composite With Open Hole

2012 ◽  
Author(s):  
Zhiyuan Zhang ◽  
Yuqiu Yang ◽  
Hiroyuki Hamada
Keyword(s):  
Mechanical Property ◽  
Unsaturated Polyester ◽  
Element Analysis ◽  
Good Correspondence ◽  
Characteristic Distance ◽  
Linear Elastic ◽  
Notched Specimens ◽  
Open Hole ◽  
Notched Strength ◽  
Glass Mat

In using process, joints and fasteners always became the weakest area around holes and easy to generate initial damage. At current study, glass chopped fiber mat and unsaturated polyester were used to fabricate glass mat composite (GMC) plates. The influence of open-hole on mechanical property was investigated from tensile test. The decreasing ratio of notched strength from unnotched strength was compared with different size of holes to evaluate the influence of holes size on the sensitivity of GMC. Two sizes of drills, were employed to make drilling hole on the materials. Different damage areas in notched specimens were distinguished. Finally, in order to describe the property of GMC in resistance on open holes, the concept of characteristic distance was introduced. The values were calculated by finite element analysis software (MSC-Marc.) in linear elastic method. Furthermore, the characteristic distance was found that it had a good correspondence with damage characteristics.

The effects of open holes on the fracture behaviors and mechanical properties of glass fiber mat composites

2015 ◽  
Vol 22 (5) ◽  
Author(s):  
Zhiyuan Zhang ◽  
Yuqiu Yang ◽  
Hiroyuki Hamada
Keyword(s):  
Mechanical Properties ◽  
Glass Fiber ◽  
Volume Fraction ◽  
Unsaturated Polyester ◽  
Good Correspondence ◽  
Characteristic Distance ◽  
Finite Element Software ◽  
Notched Specimens ◽  
Fracture Behaviors ◽  
Notched Strength

AbstractIn this paper, composite specimens were fabricated from a glass fiber chopped strand mat and unsaturated polyester resin using the hand lay-up method. To evaluate the effects of open holes on the mechanical properties, different factors, including the volume fraction of glass fiber and material thickness were investigated. Both the unnotched strength of smooth specimens and the notched strength of specimens with holes, increased as volume fraction increased, but the trends were different. For notched specimens with closer volume fractions, increased thickness or width-to-depth ratio led to a lower resistance on the open hole. In investigating the fracture behaviors of notched specimens, two different fracture areas were distinguished: parallel areas and fan-shaped areas. The length of each parallel area was measured. To evaluate the material properties, characteristic distance was calculated using linear elastic methods in finite element software (MSC-Marc, MSC Software Corporation, Tokyo, Japan). The results revealed that characteristic distance has a good correspondence with parallel area length.

Application of Two Methods for Notch Fatigue Life Prediction

2011 ◽  
Vol 488-489 ◽  
pp. 654-657
Author(s):  
Radu Negru ◽  
Liviu Marsavina ◽  
Hannelore Filipescu ◽  
Cristiana Caplescu
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Fatigue Life ◽  
Reduction Factor ◽  
Volumetric Method ◽  
Life Assessment ◽  
Strength Reduction Factor ◽  
Element Analysis ◽  
Linear Elastic ◽  
Notched Specimens

The aim of this paper is the application of two methods for notch fatigue life assessment, methods which are based on finite element analysis: the theory of critical distances and the volumetric method. Firstly, un-notched and notched specimens (for three different geometries) were tested in tension under constant-amplitude loading. The use of theory of critical distances (TCD) to predict the notch fatigue life involves the determination of the material characteristic length L based on experimental results obtained for the un-notched and one type of notched specimens. For the others notched geometries, based on linear-elastic finite element analysis, the fatigue strength is predicted using the TCD. In order to apply the volumetric method, elastic-plastic stress field around notches are considered and notch strength reduction factor are determined. Finally, the predictions of the two methods were compared with experimental fatigue data for notched specimens.

scholarly journals Open hole size effects on tensile properties of 3D braided composites

2021 ◽  
Vol 72 (05) ◽  
pp. 545-551
Author(s):  
SHUANGQIANG LIANG ◽  
QIHONG ZHOU ◽  
GE CHEN
Keyword(s):  
Size Effects ◽  
Uniaxial Tensile ◽  
Braided Composites ◽  
Notched Specimen ◽  
Stress Criterion ◽  
Notched Specimens ◽  
3D Braided Composites ◽  
Open Hole ◽  
Uniaxial Tensile Stress ◽  
Notched Strength

Owing to the excellent integrated structure, notch-insensitivity, delamination-free characteristics, 3D braided composites have a broad range of engineering applications. In this paper, the notch size effects on two types of 3D braided composites were experimentally examined. Style I incorporated 40% of longitudinal lay-in yarns. Style II was the pure braids. The Point Stress Criterion (PSC) was applied to predict the open-hole strength of 3D braided composites. It is found the 3D braided composites can keep higher proportion residual strength after involving the different circular hole sizes compared to plain woven laminates. The open-hole pure braided specimen shows better performance than that the braids with longitudinal yarns, the lay-in longitudinal yarns improve neither specimens’ un-notched strength, nor the modulus. The predicted open-hole strength were compared with experimental results. The traditional analytical method can predict the open-hole strength of 3D braided composite to some extent. Under uniaxial tensile stress, the failure behaviour of two types of 3D braided specimens are different. For un-notched specimen, clear cracks usually show up on the Style II specimen, while it is not true for Style I coupon. For notched specimen, the crack of both notched specimens will propagate along the notch and finally render the specimen to fail

Tensile and Bending Behavior of Melt Growth Al2O3/YAG Composite at Ultra High Temperatures (1773-2023K)

2005 ◽  
Vol 475-479 ◽  
pp. 1091-1096
Author(s):  
Shojiro Ochiai ◽  
Yuushi Sakai ◽  
K. Sato ◽  
T. Ueda ◽  
Kohei Morishita ◽  
...  
Keyword(s):  
High Temperatures ◽  
Yttrium Aluminum Garnet ◽  
Plastic Zone Size ◽  
Tensile Tests ◽  
Element Analysis ◽  
Notched Specimens ◽  
Speed Up ◽  
Displacement Speed ◽  
Notched Strength ◽  
Increasing Temperature

The deformation and fracture behavior at 1773-2023K of the unidirectionally solidified eutectic Al2O3/YAG (Yttrium-Aluminum Garnet with the composition of Y3Al5O13) ceramic composite was investigated. The stress-stain curve and strength of unnotched and notched specimens, measured by bending and tensile tests, showed that (a) both unnotched and notched specimens fractured in a brittle manner at low temperatures and at high displacement speeds, but in a ductile manner at high temperatures and at low displacement speeds, and (b) the notched strength increased, reaching maximum, and decreased with increasing temperature and decreasing displacement speed. The increase in the notched strength with increasing temperature and decreasing displacement speed up to the maximum value was accounted for by the increase in plastic zone size ahead of the notch, and the decrease with further increasing temperature and decreasing displacement speed by the loss of the stress carrying capacity of the yielded ligament, based on the finite element analysis.

Notched Strength and Fractures Behavior of Chopped Glass Mat Reinforced Unsaturated Plastics

2011 ◽  
Author(s):  
Ryuiti Nishida ◽  
Ying Yu ◽  
Yuqiu Yang ◽  
Hiroyuki Hamada
Keyword(s):  
Finite Element ◽  
Stress Analysis ◽  
Natural Fiber ◽  
Drill Hole ◽  
Short Fiber ◽  
Fiber Mats ◽  
Characteristic Distance ◽  
Finite Element Stress Analysis ◽  
Notched Strength ◽  
Glass Mat

Glass chopped fiber mats have been used as traditional reinforcements for fiber reinforced plastics. However, the literature is found limited even it has a long history. However short fiber mats is considered to be suitable reinforcement configuration for natural fiber or filled composites because the natural fiber is inherently short fiber. Various fiber textile technologies are available to be used to fabricate the fiber mats structure, for example needle punching process. Therefore the relation between different textile manufacturing techniques (the fiber mat structure) and the composites properties is considered necessary to be should be fully understood. Chopped glass mat reinforced composite was used as experimental materials and the fracture behavior of the specimens with drill-hole was investigated. Acoustic emission (AE) measurement was carried out by using Dual AE measurement system with both 140 KHz and 1 MHz sensors to understand the fiber and matrix fracture behaviors simultaneously. Also the characteristic distance was calculated experimentally and was compared theoretically with the values obtained from finite element stress analysis. It is found that the notched strength decrease by drilling a hole in the center. While regarding to the effect of w/d ratio i.e. the ratio of width to the diameter of the drill-hole, w/d of 3 specimens seems to have relative higher notched strength as compared to 2 or 5 w/d specimens. During the tensile test AE signals which detected by both 140 kHz and 1MHz are found to be generated almost at the same time. Additionally, the white area before the final broken seems to relative to the characteristic distance calculated by finite element stress analysis.

Fatigue Failure Analysis Using the Theory of Critical Distance

2011 ◽  
Vol 462-463 ◽  
pp. 663-667 ◽  
Author(s):  
Ruslizam Daud ◽  
Ahmad Kamal Ariffin ◽  
Shahrum Abdullah ◽  
Al Emran Ismail
Keyword(s):  
Stress Concentration ◽  
Fatigue Failure ◽  
Notch Root ◽  
High Stress ◽  
Critical Distance ◽  
Future Research ◽  
Element Analysis ◽  
Linear Elastic ◽  
The Finite Element Analysis ◽  
Elastic Fracture

This paper explores the initial potential of theory of critical distance (TCD) which offers essential fatigue failure prediction in engineering components. The intention is to find the most appropriate TCD approach for a case of multiple stress concentration features in future research. The TCD is based on critical distance from notch root and represents the extension of linear elastic fracture mechanics (LEFM) principles. The approach is allowing possibilities for fatigue limit prediction based on localized stress concentration, which are characterized by high stress gradients. Using the finite element analysis (FEA) results and some data from literature, TCD applications is illustrated by a case study on engineering components in different geometrical notch radius. Further applications of TCD to various kinds of engineering problems are discussed.

Strength envelope of granular soil stabilized by multi-axial geogrid in large triaxial tests

2020 ◽  
Vol 57 (3) ◽  
pp. 448-452 ◽  
Author(s):  
A.S. Lees ◽  
J. Clausen
Keyword(s):  
Triaxial Compression ◽  
Triaxial Tests ◽  
Compression Tests ◽  
Failure Envelope ◽  
Element Analysis ◽  
Linear Elastic ◽  
Perfectly Plastic ◽  
Elastic Perfectly Plastic ◽  
Triaxial Compression Tests ◽  
Properties Of Soil

Conventional methods of characterizing the mechanical properties of soil and geogrid separately are not suited to multi-axial stabilizing geogrid that depends critically on the interaction between soil particles and geogrid. This has been overcome by testing the soil and geogrid product together as one composite material in large specimen triaxial compression tests and fitting a nonlinear failure envelope to the peak failure states. As such, the performance of stabilizing, multi-axial geogrid can be characterized in a measurable way. The failure envelope was adopted in a linear elastic – perfectly plastic constitutive model and implemented into finite element analysis, incorporating a linear variation of enhanced strength with distance from the geogrid plane. This was shown to produce reasonably accurate simulations of triaxial compression tests of both stabilized and nonstabilized specimens at all the confining stresses tested with one set of input parameters for the failure envelope and its variation with distance from the geogrid plane.

scholarly journals Reinforcing Effect of Carbon Nanotubes/Surfactant Dispersions in Portland Cement Pastes

2018 ◽  
Vol 2018 ◽  
pp. 1-9 ◽  
Author(s):  
Oscar A. Mendoza Reales ◽  
Caterin Ocampo ◽  
Yhan Paul Arias Jaramillo ◽  
Juan Carlos Ochoa Botero ◽  
Jorge Hernán Quintero ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Cement Matrix ◽  
Multiwalled Carbon ◽  
Element Analysis ◽  
Cement Pastes ◽  
Reinforcing Effect ◽  
Linear Elastic ◽  
Crack Propagation Process ◽  
Negative Effect ◽  
The Individual

Decoupling the individual effects of multiwalled carbon nanotubes (MWCNTs) and surfactants when used as reinforcement materials in cement-based composites is aimed in this study. Powder MWCNTs were dispersed in deionized water using different types of surfactants as chemical dispersing agents and an ultrasonic tip processor. Cement pastes with carbon nanotubes additions of 0.15% by mass of cement were produced in two steps: first, the MWCNT/surfactant dispersions were combined with the mixing water, and then, cement was added and mixed until a homogeneous paste was obtained. Mechanical properties of the pastes cured at 7 days were measured, and their fracture behavior was characterized using the linear elastic finite element analysis. It was found that the reinforcing effect of MWCNT was masked by the negative effect of surfactants in the cement matrix; nevertheless, nanotubes were capable of increasing both stress and strain capacity of the composite by controlling the crack propagation process at the tip of the crack.

scholarly journals Experimental Study on Mechanical Property of Stiffening-ribbed-hollowpipe Reinforced Concrete Girderless Floor with Four Clamped Edges Supported

2013 ◽  
Vol 7 (1) ◽  
pp. 170-178 ◽  
Author(s):  
Weijun Yang ◽  
Yongda Yang ◽  
Jihua Yin ◽  
Yushuang Ni
Keyword(s):  
Mechanical Property ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Reinforced Concrete ◽  
Large Scale ◽  
Load Test ◽  
Static Load Test ◽  
Loading Test ◽  
Element Analysis ◽  
Clamped Edges

In order to study the basic mechanical property of cast-in-place stiffening-ribbed-hollow-pipe reinforced concrete girderless floor, and similarities and differences of the structural performance compared with traditional floor, we carried out the destructive stage loading test on the short-term load test of floor model with four clamped edges supported in large scale, and conducted the long-term static load test. Also, the thesis conducted finite element analysis in virtue of ANSYS software for solid slab floor, stiffening-ribbed-hollow-pipe floor and tubular floor. The experiment indicates that the developing process of cracks, distribution and failure mode in stiffening-ribbed-hollow-pipe floor are similar to that of solid girderless floor, and that this kind of floor has higher bearing capacity and better plastic deformation capacity. The finite element analysis manifests that, compared with solid slab floor, the deadweight of stiffening-ribbed-hollow-pipe floor decreases on greater level while deformation increases little, and that compared with tubular floor, this floor has higher rigidity. So stiffening-ribbed-hollow-pipe reinforced concrete girderless floor is particularly suitable for long-span and large-bay building structure.

scholarly journals Open-Hole 3D Braided Composites Strength Prediction and Stress Analysis

2020 ◽  
Vol 38 (4) ◽  
pp. 889-896
Author(s):  
Shuangqiang Liang ◽  
Chenglong Zhang ◽  
Ge Chen ◽  
Qihong Zhou ◽  
Frank Ko
Keyword(s):  
Failure Analysis ◽  
Progressive Failure ◽  
Failure Criteria ◽  
Element Analysis ◽  
Braided Composite ◽  
Failure Initiation ◽  
Geometry Model ◽  
Progressive Failure Analysis ◽  
3D Braided Composites ◽  
Open Hole

The stress concentration caused by notches is a common engineering issue for composite structure application. 3D braided composite possess excellent damage tolerance compared to common laminates. The tensile properties of 3D braided composite with open-hole and un-notched were experimentally examined. The mechanic properties of 3D braided composite in other directions are predicted using FGM (Fabric Geometry Model) and finite element analysis. The stress distributions around the hole and perpendicular to the loading direction are analyzed based on Abaqus software. The simulation results were compared with Lekhnitskii's analytical study. The open-hole strength of 3D braided composite was predicted respectively using Average stress failure criteria, Point stress failure criteria (PSC), and also the progressive failure analysis based on different failure criteria. The predicted strength results were compared to the experimental values. The results show the PSC predicted strength matched the experiment, while the progressive failure analysis can predict the failure initiation, propagation and final failure mode.

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