Impact Resistance of SM Joints Formed With ICA

2002 ◽  
Vol 124 (4) ◽  
pp. 374-378 ◽  
Author(s):  
C. M. Lawrence Wu ◽  
Robert K. Y. Li ◽  
N. H. Yeung
Keyword(s):  
Impact Damage ◽  
Impact Resistance ◽  
High Energy ◽  
Bending Test ◽  
Conductive Adhesives ◽  
Energy Impact ◽  
Split Hopkinson ◽  
Post Impact ◽  
Impact Bending ◽  
The Impact

Isotropic conductive adhesives (ICA) have been considered as replacement materials for lead-tin solder alloys. In this paper, the post-impact shear strength of ICA surface mount (SM) joints was obtained experimentally and compared with that of SM lead-tin joints. The dynamic impact energy was provided in the form of three-point bending on the PCB using equipment called the split Hopkinson bar. Strain rates of over 4000/s were used for the impact bending test. The action of impact bending was used to simulate the effect on the PCB and the interconnection as a result of high energy impact on an electronic equipment. Shear test was then performed to examine the change in strength of the ICA joints as a result of impact damage. It was found that the SM ICA joints failed due to impact at a strain rate just over 4000/s. Microstructural examination carried out using a scanning electron microscope revealed that the interface between the ICA and copper pad on the PCB was the weakest region of the joint.

Impact Resistance of SM Joints Formed With ICA

2003 ◽  
Vol 125 (1) ◽  
pp. 93-97 ◽  
Author(s):  
C. M. Lawrence Wu ◽  
Robert K. Y. Li ◽  
N. H. Yeung
Keyword(s):  
Impact Damage ◽  
Impact Resistance ◽  
High Energy ◽  
Bending Test ◽  
Conductive Adhesives ◽  
Energy Impact ◽  
Split Hopkinson ◽  
Post Impact ◽  
Impact Bending ◽  
The Impact

Isotropic conductive adhesives (ICA) have been considered as replacement materials for lead-tin solder alloys. In this paper, the post-impact shear strength of ICA surface mount (SM) joints was obtained experimentally and compared with that of SM lead-tin joints. The dynamic impact energy was provided in the form of three-point bending on the PCB using equipment called the split Hopkinson bar. Strain rates of over 4000/s were used for the impact bending test. The action of impact bending was used to simulate the effect on the PCB and the interconnection as a result of high energy impact on an electronic equipment. Shear test was then performed to examine the change in strength of the ICA joints as a result of impact damage. It was found that the SM ICA joints failed due to impact at a strain rate just over 4000/s. Microstructural examination carried out using a scanning electron microscope revealed that the interface between the ICA and copper pad on the PCB was the weakest region of the joint.

An Enhanced Time-Reversal Method for Impact Damage Monitoring on Plate-Like Structures

2012 ◽  
Vol 525-526 ◽  
pp. 365-368
Author(s):  
Chun Lin Chen ◽  
Yu Long Li ◽  
Fuh Gwo Yuan
Keyword(s):  
Time Reversal ◽  
Composite Structures ◽  
Impact Damage ◽  
High Energy ◽  
Low Velocity ◽  
Energy Impact ◽  
Location Detection ◽  
Focusing Property ◽  
The Impact ◽  
Impact Events

Based on the self-focusing property of time-reversal (T-R) concept, a time focusing parameter was suggested to improve the impact source identification method developed in authors previous work. This paper presents a further study on monitoring relatively high energy impact events which caused induced damage on structures. Numerical verifications for a finite isotropic plate and a composite plate under low velocity impacts are performed to demonstrate the versatility of T-R method for impact location detection with induced plastic deformation and delamination damage on metallic and composite structures respectively. The focusing property of T-R concept was adequately utilized to detect impact/damage location. The results show that impact events with various features can be localized using T-R method by introducing the time focusing parameter. It is suited to monitor serious impact events on plate like structures in practice in future.

Containment and Arrest of Blade Shedding in Gas Turbine Engines Using Novel Dual-Ring Design

2021 ◽  
Author(s):  
Prayers Roy ◽  
Shaker A. Meguid
Keyword(s):  
Energy Absorption ◽  
Impact Damage ◽  
Impact Resistance ◽  
High Energy ◽  
Element Analysis ◽  
Single Ring ◽  
High Energy Absorption ◽  
Interfacial Gap ◽  
The Impact ◽  
Dual Ring

Abstract In this paper, we examine the energy absorption and containment capabilities of a newly proposed dual-ring design accounting for interactions between a released blade and fully bladed fan disk using 3D finite element analysis. The components of this dual-ring design are strategically selected to ensure high energy absorption and high impact resistance, thus leading to reduced damage of the disk and increased safety. Three containment ring designs are examined: (i) conventional single-ring design composed of one of titanium, aluminum or Kevlar, (ii) a newly proposed aluminium-Kevlar dual-ring arrangement, and (iii) dual-ring arrangement with an interfacial gap between them to arrest and contain the released blade and ensure free passage of the trailing blades. The results of our numerical simulations indicate that although the single-ring design resists penetration and contains the released blade within the confines of the disk, it does not remove the released blade from the path of the trailing blades leading to severe damage to the fan disk. On the contrary, our new dual-ring design, which contains an interfacial gap, has potential to successfully arrest the released blade within the confines of the ring and out of the path of the trailing blades. This design significantly can reduce the impact damage to the fan disk and reduces kinetic energy of the released blade to near zero in less than half a rotation of the fan disk.

scholarly journals Impact Performance and Bending Behavior of Carbon-Fiber Foam-Core Sandwich Composite Structures in Cold Arctic Temperature

2020 ◽  
Vol 4 (3) ◽  
pp. 133
Author(s):  
M.H. Khan ◽  
Bing Li ◽  
K.T. Tan
Keyword(s):  
Carbon Fiber ◽  
Impact Damage ◽  
Matrix Cracking ◽  
Face Sheet ◽  
Foam Core ◽  
Impact Performance ◽  
Post Impact ◽  
Bending Behavior ◽  
Impact Bending ◽  
The Impact

This study investigates the impact performance, post-impact bending behavior and damage mechanisms of Divinycell H-100 foam core with woven carbon fiber reinforced polymer (CFRP) face sheets sandwich panel in cold temperature Arctic conditions. Low-velocity impact tests were performed at 23, −30 and −70 °C. Results indicate that exposure to low temperature reduces impact damage tolerance significantly. X-ray microcomputed tomography is utilized to reveal damage modes such as matrix cracking, delamination and fiber breakage on the CFRP face sheet, as well as core crushing, core shearing and debonding in the Polyvinyl Chloride (PVC) foam core. Post-impact bending tests reveal that residual flexural properties are more sensitive to the in-plane compressive property of the CFRP face sheet than the tensile property. Specifically, the degradation of flexural strength strongly depends on pre-existing impact damage and temperature conditions. Statistical analyses based on this study are employed to show that flexural performance is dominantly governed by face sheet thickness and pre-bending impact energy.

Characterization of Resin-Injection Repair of Impact Damage in Polymer Matrix Composite

2015 ◽  
Author(s):  
Ritwik Prashant Moghe ◽  
Raghu V. Prakash ◽  
Deepika Sudevan ◽  
Hema Katta Shambhayya
Keyword(s):  
Polymer Matrix ◽  
Impact Damage ◽  
Damage Zone ◽  
Injection Pressure ◽  
High Energy ◽  
Low Energy ◽  
Repair Method ◽  
Energy Impact ◽  
Resin Injection ◽  
The Impact

Resin injection repair of impact damage in polymer matrix composites is studied using an in-house developed repair methodology. Carbon fiber reinforced polymeric composite specimens were impacted for three levels of impact damage (23 J, 35 J and 51 J — typical of low energy, medium energy, high energy) using a drop tup test rig and the damage zone was characterized using ultrasonic C-scan technique. The impact damaged specimens were repaired using a resin infiltration method. The selection of low viscosity room temperature curing resin, and process parameters such as resin injection pressure and vacuum levels to be maintained were studied to arrive at optimum repair method. The tension, compression strength of laminates prior to impact and post-impact as well as post-repair was studied to assess the quality of repair method. The results indicate that the chosen resin injection repair is effective for the repair of low energy impact damage but not in the case of medium and high energy impact damage.

High-Energy Impact Certification of Aero Structures: Experiments and Numerical Simulations

2015 ◽  
Vol 237 ◽  
pp. 233-238
Author(s):  
Grzegorz Socha ◽  
Sebastian Szałkowski ◽  
Andrzej Zbrowski
Keyword(s):  
Numerical Simulations ◽  
Impact Resistance ◽  
Experimental Tests ◽  
High Energy ◽  
Sustainable Technologies ◽  
Impact Tests ◽  
Energy Impact ◽  
Particle Hydrodynamics ◽  
Real Objects ◽  
The Impact

The article presents the test results obtained from the “Research methods and systems for the investigation on impact resistance of elements of aero structures and land vehicles aimed at the assessment of passenger safety” R&D project that was jointly executed by the Institute of Aviation, the Institute for Sustainable Technologies – National Research Institute, and the PZL Mielec. The main objective of the project was to perform impact tests of the windscreen and the vertical stabilizer of the PZL M28 Skytruck. The experimental tests were conducted for real objects in full scale. The investigations were carried out using an original 250 mm pneumatic gun. Apart from the impact tests, the project was also focused on numerical simulations of impacts employing the Finite Element Method (test object modelling) and the Smoothed Particle Hydrodynamics methods (the model of the gelatine projectile). The authors compare the results of experimental tests and numerical simulations. They present the differences in the results obtained and analyse the reasons behind these discrepancies, and based on the analysis, they conclude that the main cause for them is the simplified mathematical model describing the behaviour of the material subjected to dynamic loads, which was used in numerical simulations.

scholarly journals Flexural Toughness as an Attribute for Impact Damage Evaluation of Composite Laminates

2011 ◽  
Author(s):  
Mohammad Alemi-Ardakani ◽  
Abbas S. Milani ◽  
Spiro Yannacopoulos ◽  
David Trudel-Boucher ◽  
Golnaz Shokouhi
Keyword(s):  
Mechanical Properties ◽  
Composite Materials ◽  
Composite Laminates ◽  
Visual Inspection ◽  
Impact Damage ◽  
Impact Resistance ◽  
Damage Evaluation ◽  
Flexural Toughness ◽  
Post Impact ◽  
The Impact

Popularity and application of composite materials are increasing in several industries including transportation, construction and aerospace. The mechanical properties of these materials should be known to engineers to be able to design/select new products. Impact resistance is one of the properties which have been studied extensively over the past years and still is an ongoing topic in composites research. Since analytical solutions have not been fully developed for the impact characterization of anisotropic materials, researchers often perform mechanical testing in conjunction with visual inspection methods to investigate the impact behavior of composite materials. The present study shows that flexural toughness can be used as a parameter in the design/material selection stage in the evaluation of pre- and post-impact damage of composite laminates. A series of drop-weight impact tests, using a 200J energy level, were performed on specimens made of four different stacking configurations of TWINTEX® and unidirectional laminates (polypropylene and glass fiber commingled composites) according to ASTM D7136. The damaged areas of the impacted specimens were measured using image analysis. Four-point flexural testing was then carried out, based on ASTM D7264, on both non-impacted and impacted specimens. Damaged area and flexural toughness, along with a set of other commonly used mechanical properties, were selected as measures for damage evaluation. Comparison of results before and after impact and under different criteria showed that in the present case study, visual inspection is not sufficient in predicting the post-impact properties of the tested specimens and can be misleading. On the other hand, flexural toughness could give a much clearer perspective on the extent of post-impact resistance of the specimens.

scholarly journals Bioinspired Helicoidal Composite Structure Featuring Functionally Graded Variable Ply Pitch

Materials ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5133
Author(s):  
Michele Meo ◽  
Francesco Rizzo ◽  
Mark Portus ◽  
Fulvio Pinto
Keyword(s):  
Impact Resistance ◽  
Residual Energy ◽  
Functionally Graded ◽  
Low Velocity Impact ◽  
Bending Test ◽  
Three Point Bending ◽  
Constant Pitch ◽  
Biological Structures ◽  
Post Impact ◽  
The Impact

Composite laminated materials have been largely implemented in advanced applications due to the high tailorability of their mechanical performance and low weight. However, due to their low resistance against out-of-plane loading, they are prone to generate damage as a consequence of an impact event, leading to the loss of mechanical properties and eventually to the catastrophic failure of the entire structure. In order to overcome this issue, the high tailorability can be exploited to replicate complex biological structures that are naturally optimised to withstand extreme impact loading. Bioinspired helicoidal laminates have been already studied in-depth with good results; however, they have been manufactured by applying a constant pitch rotation between each consecutive ply. This is in contrast to that observed in biological structures where the pitch rotation is not constant along the thickness, but gradually increases from the outer shell to the inner core in order to optimise energy absorption and stress distribution. Based on this concept, Functionally Graded Pitch (FGP) laminated composites were designed and manufactured in order to improve the impact resistance relative to a benchmark laminate, exploiting the tough nature of helicoidal structures with variable rotation angles. To the authors’ knowledge, this is one of the first attempts to fully reproduce the helicoidal arrangement found in nature using a mathematically scaled form of the triangular sequence to define the lamination layup. Samples were subject to three-point bending and tested under Low Velocity Impact (LVI) conditions at 15 J and 25 J impact energies and ultrasonic testing was used to evaluate the damaged area. Flexural After Impact (FAI) tests were used to evaluate the post-impact residual energy to confirm the superior impact resistance offered by these bioinspired structures. Vast improvements in impact behaviour were observed in the FGP laminates over the benchmark, with an average reduction of 41% of the damaged area and an increase in post-impact residual energy of 111%. The absorbed energy was similarly reduced (−44%), and greater mechanical strength (+21%) and elastic energy capacity (+78%) were demonstrated in the three-point bending test.

scholarly journals Sandwich panel with in-plane honeycombs in different Poisson's ratio under low to medium impact loads

2021 ◽  
Vol 60 (1) ◽  
pp. 145-157
Author(s):  
Yi Luo ◽  
Ke Yuan ◽  
Lumin Shen ◽  
Jiefu Liu
Keyword(s):  
Poisson’S Ratio ◽  
Sandwich Panel ◽  
Impact Force ◽  
Impact Resistance ◽  
Poisson's Ratio ◽  
Compression Performance ◽  
Post Impact ◽  
Local Impact ◽  
Collapse Behavior ◽  
The Impact

Abstract In this study, a series of in-plane hexagonal honeycombs with different Poisson's ratio induced by topological diversity are studied, considering re-entrant, semi-re-entrant and convex cells, respectively. The crushing strength of honeycomb in terms of Poisson's ratio is firstly presented. In the previous research, we have studied the compression performance of honeycomb with different negative Poisson's ratio. In this study, a comparative study on the local impact resistance of different sandwich panels is conducted by considering a spherical projectile with low to medium impact speed. Some critical criteria (i.e. local indentation profile, global deflection, impact force and energy absorption) are adopted to analyze the impact resistance. Finally, an influential mechanism of Poisson's ratio on the local impact resistance of sandwich panel is studied by considering the variation of core strength and post-impact collapse behavior.

IMPACT RESISTANCE PROPERTIES OF KEVLAR/GLASS FIBER HYBRID COMPOSITE LAMINATES

2015 ◽  
Vol 76 (3) ◽  
Author(s):  
Norazean Shaari ◽  
Aidah Jumahat ◽  
M. Khafiz M. Razif
Keyword(s):  
Glass Fiber ◽  
Hybrid Composite ◽  
Composite Laminates ◽  
Impact Damage ◽  
Impact Resistance ◽  
Impact Behavior ◽  
Slight Reduction ◽  
Depth Of Penetration ◽  
Damage Degree ◽  
The Impact

In this paper, the impact behavior of Kevlar/glass fiber hybrid composite laminates was investigated by performing the drop weight impact test (ASTM D7136). Composite laminates were fabricated using vacuum bagging process with an epoxy matrix reinforced with twill Kevlar woven fiber and plain glass woven fiber. Four different types of composite laminates with different ratios of Kevlar to glass fiber (0:100, 20:80, 50:50 and 100:0) were manufactured. The effect of Kevlar/glass fiber content on the impact damage behavior was studied at 43J nominal impact energy. Results indicated that hybridization of Kevlar fiber to glass fiber improved the load carrying capability, energy absorbed and damage degree of composite laminates with a slight reduction in deflection. These results were further supported through the damage pattern analysis, depth of penetration and X-ray evaluation tests. Based on literature work, studies that have been done to investigate the impact behaviour of woven Kevlar/glass fiber hybrid composite laminates are very limited. Therefore, this research concentrates on the effect of Kevlar on the impact resistance properties of woven glass fibre reinforced polymer composites.

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