Failure Strengths of Composite Additions and Repairs

2015 ◽  
Vol 40 (4) ◽  
pp. 364-371 ◽  
Author(s):  
D Tantbirojn ◽  
C Fernando ◽  
A Versluis
Keyword(s):  
Bending Test ◽  
Failure Strength ◽  
Test Beam ◽  
Four Point Bending ◽  
Significant Difference ◽  
Control Failure ◽  
Four Point Bending Test ◽  
Composite Substrates ◽  
Aged Composite ◽  
Mechanical Surface

SUMMARY Purpose When adding composite to a cured composite restoration, the intent is to achieve the same failure strength as the original restorative material. This study evaluated the failure strengths of added or repaired composite using various chemical and/or mechanical surface treatments. Methods Failure strengths were determined using a four-point bending test. Beam-shaped specimens were fabricated by adding new composite to cured composite (Filtek Supreme Ultra). The cured composites were either fresh or aged seven days (N=10-14). The composite surfaces were left unground or were ground before treatment with various combinations of roughening, acid etching, silane, and dental adhesives (conventional Adper SingleBond Plus or new multimode Scotchbond Universal) and/or tribochemistry (CoJet system). Monolithic composite specimens were the control. Failure strengths were statistically analyzed using one-way analysis of variance and the Fisher protected least significant difference (α=0.05). Results Failure strengths (mean ± standard deviation) when composite was added to unground freshly cured composites (111±25 MPa) and aged composites using a new multimode adhesive with (102±22 MPa) or without (98±22 MPa) tribochemical treatment were not significantly lower than the monolithic specimens (122±23 MPa). Grinding the surfaces of freshly cured composite significantly reduced failure strength, either with (81±30 MPa) or without (86±31 MPa) use of conventional adhesive. Failure strengths of aged composites were also significantly lower (51±21 MPa with SingleBond Plus), even after tribochemical treatment (71±29 MPa with SingleBond Plus; 73±35 MPa with Silane-Visiobond). Conclusions Using a new multimode adhesive when adding composite to freshly cured or aged composite substrates recovered the failure strength to that of the original monolithic composite.

Test Methods for Silicon Die Strength

2006 ◽  
Vol 128 (4) ◽  
pp. 419-426 ◽  
Author(s):  
M. Y. Tsai ◽  
C. H. Chen ◽  
C. S. Lin
Keyword(s):  
High Performance ◽  
Low Cost ◽  
Test Methods ◽  
Biaxial Stress ◽  
Bending Test ◽  
Published Data ◽  
Failure Strength ◽  
Surface Conditions ◽  
Four Point Bending ◽  
Four Point Bending Test

Recently, the 3D or stacked-die packages become increasingly popular for packaging ICs into a system or subsystem to satisfy the needs of low cost, small form factor, and high performance. For the applications of these packages, IC silicon wafers have to be ground to be relatively thin through the wafer-thinning processes (such as grinding, polishing, and plasma etching). The strength of dies has to be determined for the design requirement and reliability assurance of the packages. From the published data, there still exist some issues, including a large scatter existed in die strength data and difficulties in differentiating the causes of the low strength between from the wafer grinding and from wafer sawing by either the three-point bending or four-point bending test. The purposes of this study are to develop new, reliable, and simple test methods for determination of die strength, in order to improve the data scatter, and to provide a solution for differentiating the factors that affect the variability of die strength for finding out the causes of the weakness of the die strength. In this study, two new test methods, point-loaded circular plate with simple supports test (PLT-I) and point-loaded plate on elastic foundation test (PLT-II), are proposed and then evaluated by testing two groups of silicon dies with different surface conditions. The surface conditions (roughness) of the specimens are determined by atomic force microscopy and correlated to failure strength. The failure forces from both tests have to be modified by using maximum stress obtained from theories or finite element analyses to obtain the failure strength. The test results are compared to each other and further with a widely used four-point bending test. The results suggest that, unlike the four-point bending test suffering the chipping effect, both methods provide very consistent data with a small scatter for each group of specimens and can be used for identifying the effect of surface grinding (roughness) on the die strength. It is also shown that the die strength is highly dependent on the surface roughness. Accordingly, these two methods can provide not only a (biaxial) stress field similar to temperature-loaded die in the packages, but also simple, feasible, reliable, and chipping-free tests for silicon dies of dummy or real IC chips, without strict geometrical limitation, such as beam-type geometry for the three-point or four-point bending test.

Novel Test Methods for Die Strength

2005 ◽  
Author(s):  
M. Y. Tsai ◽  
C. H. Chen ◽  
C. S. Lin
Keyword(s):  
High Performance ◽  
Axial Stress ◽  
Test Methods ◽  
Bending Test ◽  
Published Data ◽  
Failure Strength ◽  
Element Analysis ◽  
Surface Conditions ◽  
Four Point Bending ◽  
Four Point Bending Test

Recently, the 3-D or stacked-die packages are increasingly popular for packaging ICs into a system or subsystem to satisfy the needs of low cost, small form factor, and high performance. For the applications of these packages, IC wafers have to be ground to be relatively thin through the wafers thinning processes (such as grinding, polishing, and plasma etching). The strength of dies has to be determined for the design requirement and thus assuring reliability of the packages. From the published data, there still exist some issues including a large scatter existed in die strength data, and difficulties with differentiating the causes of the low strength from the grinding or die sawing either by three-point bending or four-point bending test. The purposes of this study is to develop new, reliable and simple test methods for determination of die strength to improve the data scatter and also provide a solution for differentiating the factors that affect the variability of die strength, in order to find out the causes of the weakness of the die strength. In this study, two new test methods, point-loaded circular plate with simple supports test (PLT-I) and point-loaded plate on elastic foundation test (PLT-II) are proposed and evaluated by testing two groups of silicon dies with different surface conditions. The surface conditions (roughness) of the specimens are determined by atomic force microscopy and correlated to failure strength. The failure forces from both tests have to be modified by using maximum stress obtained from theory or finite element analysis to get the failure strength. The test results are compared with each other and further with widely-used four-point bending test. The results suggest that, unlike the four-point bending test, both methods provide very consistent data with a small scatter for these two groups of specimens, and indicated the die strength is highly dependent on the surface roughness. Accordingly, these two methods can provide not only a (bi-axial) stress field similar to temperature-loaded die in the packages, but also simple, feasible, reliable and chipping-free tests for silicon dies of dummy or real IC chips, without strict geometrical limitation, such as beam-type geometry for three-point or four-point bending test.

scholarly journals Structural behaviour of PSCC slab panel under four-point bending test

2021 ◽  
Vol 1144 (1) ◽  
pp. 012039
Author(s):  
M A Iman ◽  
N Mohamad ◽  
A A A Samad ◽  
Steafenie George ◽  
M A Tambichik ◽  
...  
Keyword(s):  
Bending Test ◽  
Structural Behaviour ◽  
Four Point Bending ◽  
Four Point Bending Test

Manufacturing a carbon/epoxy NACA 23018 airfoil skin using a circular braiding machine: experimental and numerical study

2021 ◽  
pp. 152808372199377
Author(s):  
Jalil Hajrasouliha ◽  
Mohammad Sheikhzadeh
Keyword(s):  
Numerical Study ◽  
Filament Winding ◽  
Bending Test ◽  
Elastic Response ◽  
Manufacturing Processes ◽  
Fiber Reinforced Composite ◽  
Four Point Bending ◽  
Reinforced Composite ◽  
Four Point Bending Test ◽  
Meso Scale

In the interest of reducing the weight and also cost of blade skins, various automatic preform manufacturing processes were developed including tape laying, filament winding and braiding. Among them, the circular braiding process was found to be an efficient method in producing seamless preforms on mandrels with various geometries. In this regard, an attempt was made to produce a carbon fiber reinforced composite with the shape of NACA 23018 airfoil using a circular braiding machine. Thus, suitable wooden mandrels were manufactured using NACA 23018 airfoil coordinates, which were obtained by assuming the perimeter of 20 cm. Furthermore, both biaxially and triaxially braided preforms were produced and subsequently impregnated with epoxy resin through an appropriate fabrication method. To assess their performance, four-point bending test was carried out on samples. Ultimately, the elastic response of braided composite airfoils was predicted using a meso-scale finite element modeling and was validated with experimental results.

Research on Damage and Bending Properties of AZ31 Magnesium Alloy

2012 ◽  
Vol 184-185 ◽  
pp. 1163-1166
Author(s):  
Xi An Xie ◽  
Gao Feng Quan
Keyword(s):  
Magnesium Alloy ◽  
Applied Load ◽  
Bending Strength ◽  
Az31 Magnesium Alloy ◽  
Bending Test ◽  
Bending Properties ◽  
Four Point Bending ◽  
Heat Treated ◽  
Four Point Bending Test ◽  
Initial Cracks

Through the four-point bending test of lath-shaped heat treated AZ31 magnesium alloy, the bending properties and damage characteristics were explored. The results show that the optimal bending strength of the magnesium alloy were 355.1MPa and 259.2MPa for extruded and cast samples, respectively, after corresponding heat treatment with 350°C, 90min and 400°C, 30min. The initial cracks both occurred at the loading point after applied load exceeded the yield limit of AZ31 magnesium alloy. Surface bump, cracks and other damage morphology accompanied by a large number of twinning organizations were found on the surface of the samples.

scholarly journals Geometry Effects in Four-Point Bending Test for Thin Sheet Studied by Finite Element Simulation

2016 ◽  
Vol 57 (3) ◽  
pp. 335-343 ◽  
Author(s):  
Xiaolong Dong ◽  
Hongwei Zhao ◽  
Lin Zhang ◽  
Hongbing Cheng ◽  
Jing Gao
Keyword(s):  
Finite Element ◽  
Finite Element Simulation ◽  
Thin Sheet ◽  
Bending Test ◽  
Four Point Bending ◽  
Element Simulation ◽  
Four Point Bending Test ◽  
Geometry Effects
Sign in / Sign up

Export Citation Format

Share Document