REPRESENTATION, CHARACTERIZATION AND SIMULATION OF TOOL-PART INTERACTION AND ITS EFFECTS ON PROCESS-INDUCED DEFORMATIONS IN COMPOSITES

2021 ◽  
Author(s):  
CALEB SCHOENHOLZ ◽  
DANIEL SLADE ◽  
ENRICO ZAPPINO ◽  
MARCO PETROLO ◽  
NAVID ZOBEIRY
Keyword(s):  
Mechanical Performance ◽  
Surface Condition ◽  
Mechanical Analysis ◽  
Interfacial Stress ◽  
Shear Stresses ◽  
Current Analysis ◽  
Degree Of Cure ◽  
Dimensional Changes ◽  
Tool Surface ◽  
Composites Processing

The interaction between a tool and part during composites processing contributes to the formation of residual stresses and dimensional changes. A resultant mismatch of part geometries during assembly can cause a potential loss of mechanical performance in aerospace structures. Costly shimming steps are needed to compensate for processinduced deformations and satisfy specifications on mechanical performance. Due to difficulties associated with accurate measurement of interfacial shear stresses, current analysis methods fail to represent the interaction between a tool and part throughout processing. A combined approach to represent, characterize, and simulate tool-part interaction and its effects on dimensional changes is proposed. First, a characterization method was established using a custom Dynamic Mechanical Analysis (DMA) shear test setup to measure tool-part interfacial stress development in a simulated autoclave curing environment. Tool-part interfacial stresses were characterized for Toray T800S/3900-2 UD prepreg as a function of temperature, degree of cure, strain rate, and tool surface condition. Then, a previously developed numerical model was modified to include the effects of tool-part interaction in predicting dimensional changes of L-shape parts. For validation, composite parts were fabricated on tools with different surface conditions and successfully compared to simulation results. This paper demonstrates that tool-part interaction significantly impacts the spring-in of angled composite parts. The proposed method is a comprehensive and practical approach to study and simulate the effects of tool-part interaction. The results of this paper can be used to understand the complex interaction between a tool and part throughout processing and potentially mitigate processinduced deformations.

Water damage in glass fibre/resin composites

1969 ◽  
Vol 312 (1511) ◽  
pp. 553-564 ◽  
Keyword(s):  
Coupling Agent ◽  
Fibre Surface ◽  
Linear Shrinkage ◽  
Fused Silica ◽  
Water Soluble ◽  
Hot Water ◽  
Interfacial Stress ◽  
Shear Stresses ◽  
Dimensional Changes ◽  
Glass Fibres

Thin films of polyester resin containing glass fibres of several different compositions have been exposed to water at three different temperatures (20, 60, 100°C) and examined by means of optical and scanning electron microscopy. The incidence and development of fibre debonding has been studied by using the optical anisotropy arising from resin shrinkage on to the fibres during cure. To aid interpretation of these experiments, measurements have been made of resin dimensional changes produced by water immersions. At each temperature, the first response to diffused water is resin swelling and, in hot water, this is superseded by shrinkage, the magnitude of which becomes considerable after prolonged immersion, e. g. 8% linear shrinkage after 2000 h in boiling water. Evidence is reported suggesting that this shrinkage is mainly due to leaching of low molecular weight material from the resin. The interfacial bond between resin and clean glass fibres is rapidly destroyed by diffused water at all three temperatures. However, the use of a coupling agent produces vast improvements in bond life. In fact, debonding in the presence of a coupling agent has been observed only for hot water immersions; even then, the bond withstands the interfacial tension present during early resin swelling and is destroyed very much later when the interfacial stress is compressive owing to resin shrinkage. The mechanism by which this debonding is eventually initiated depends on glass composition. With ‘E’ and ‘C’ glass fibres, bond fracture is due to osmotic pressure generated at the interface by water soluble constituents leached from the fibre, and is often accompanied by the growth of cracks into the resin from the fibre surface. With fused silica fibres, which contain negligible amounts of impurities, small regions of debonded interface appear at fibre ends after much longer immersion times and are attributed to high interfacial shear stresses caused by resin shrinkage. Debonding facilitates relative longitudinal movement between fibre and resin, enabling each fibre end to act as a rigid indentor pushing into the adjacent resin. In hot water, resin indentation cracks result and subsequent resin shrinkage and gross plastic deformation lead to their displacement along the fibres, followed by the successive nucleation and displacement of further indentation cracks.

Mechanical performance and failure criterion of coral concrete under combined compression-shear stresses

2021 ◽  
Vol 288 ◽  
pp. 123050
Author(s):  
Bing Liu ◽  
Jingkai Zhou ◽  
Xiaoyan Wen ◽  
Jianhua Guo ◽  
Zhiheng Deng ◽  
...  
Keyword(s):  
Failure Criterion ◽  
Mechanical Performance ◽  
Shear Stresses

Enhancement of the Mechanical Properties of PEBAX Graphene Nanocomposite Using Supercritical Fluid Assisted Extrusion Polymer Processing Technique

2017 ◽  
Vol 883 ◽  
pp. 75-84 ◽  
Author(s):  
Nireeksha Karode ◽  
Laurence Fitzhenry ◽  
Siobhán Matthews ◽  
Philip Walsh ◽  
Austin Coffey
Keyword(s):  
Mechanical Properties ◽  
Carbon Dioxide ◽  
Supercritical Carbon Dioxide ◽  
Mechanical Performance ◽  
Mechanical Analysis ◽  
Polymer Processing ◽  
Processing Technique ◽  
Graphene Nanocomposites ◽  
Mechanical Tensile ◽  
Supercritical Carbon

Medical tubing used in minimally invasive devices presents a number of design considerations depending on the material used, design requirements (such as sufficient stiffness, flexibility and biocompatibility) and processing conditions. Currently, manufacturing industries adopt co-extrusion systems to meet design specifications, by using multilayer configuration leading to higher cost per device and increased complexity. This paper investigates the mechanical performance of nanocomposites using supercritical carbon dioxide assisted polymer processing technique. The use of innovative medical compounds such as PEBAX graphene nanocomposites have resulted in measurable improvements in mechanical properties. This study also presents the effect of supercritical carbon dioxide on the mechanical and physical properties of the polymer matrix. The mechanical properties have been investigated using dynamic mechanical analysis (DMA) and mechanical tensile test, where sufficient reinforcement was observed depending on the composition of graphene within PEBAX matrix. ATR-FTIR was used to further analyze the effect of supercritical carbon dioxide and interactions within the polymer composite matrix.

The Effect of Stirring Tool Surface Condition on Wear Characteristics in Friction Stir Welding (FSW) Process

2021 ◽  
Vol 880 ◽  
pp. 57-62
Author(s):  
Normariah Che Maideen ◽  
Salina Budin ◽  
Koay Mei Hyie ◽  
Nor Azirah Mohd Fohimi
Keyword(s):  
Heat Treatment ◽  
Friction Stir Welding ◽  
Surface Condition ◽  
Welding Process ◽  
Wear Characteristics ◽  
Rotating Speed ◽  
Friction Stir ◽  
Ticn Coating ◽  
Tool Surface

Stirring tool is one of the important factor that contribute to the successful of Friction Stir Welding (FSW). Role of tool, is to heat the welding zone and stir the material along the process. Many studies have been conducted by other researchers to improve the performance of stirring tool. Similar to this work, it is aimed to investigate and analyze the effect of stirring tool surface condition on wear characteristics in friction stir welding process. Four tools have been fabricated with pre-determined surface condition. Tool 1: H13 without heat treatment and without coating. Tool 2: H13 with heat treatment only. Tool 3: H13 with TiCN coating only and Tool 4: H13 with heat treatment and with TiCN coating. Friction stir welding was performed to test and verify the performance of fabricated tools. Process parameter used are 1270 RPM for rotating speed while 218 mm/min for welding speed. From the result, Tool 4 performed better in terms of physical wear as well as wear rate.

Low-Density Phenolic Syntactic Foams: Processing and Properties

2007 ◽  
Vol 26 (4) ◽  
pp. 229-244 ◽  
Author(s):  
Bibin John ◽  
C.P. Reghunadhan Nair ◽  
K.N. Ninan
Keyword(s):  
Phenolic Resin ◽  
Mechanical Performance ◽  
Volume Fraction ◽  
Mechanical Analysis ◽  
Low Density ◽  
Syntactic Foams ◽  
Novolac Resin ◽  
High Concentration ◽  
Volume Percentage ◽  
Propargyl Ether

Low-density phenolic syntactic foams with different volume percentages of microballoons were processed and their mechanical performance has been evaluated in terms of tensile, flexural, compressive and the corresponding specific properties. Tensile and flexural strength increased with volume fraction of microballoon and optimized at 72–74 percentage by volume of microballoon. Both the properties decreased with further addition of microballoon. The corresponding specific properties also manifested a similar order. Compressive and specific compressive strength decreased with increase in microballoon volume percentage. The flexural and compressive modulus values followed the same trend as the strength values. The properties of phenolic syntactic foams were compared with syntactic foams based on an addition cure phenolic resin, Propargyl Ether Novolac resin (PN). The mechanical properties of the latter were inferior to those of phenolic syntactic foams. The morphology of the failed samples as examined by SEM showed that failure occurred by a combination of matrix and microballoon failure at low microballoon loading whereas it occurred by microballoon cracking and resin to microballoon debonding at high concentration of filler. The dynamic mechanical analysis of phenolic and PN resin syntactic foams showed a higher use temperature for PN system in comparison to phenolic.

Viscoelastic behavior of an epoxy resin during cure below the glass transition temperature: Characterization and modeling

2018 ◽  
Vol 53 (2) ◽  
pp. 155-171 ◽  
Author(s):  
Alice Courtois ◽  
Martin Hirsekorn ◽  
Maria Benavente ◽  
Agathe Jaillon ◽  
Lionel Marcin ◽  
...  
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Epoxy Resin ◽  
Viscoelastic Behavior ◽  
Mechanical Analysis ◽  
Strain History ◽  
Model Parameters ◽  
Degree Of Cure ◽  
Model Predictions

This paper presents a viscoelastic temperature- and degree-of-cure-dependent constitutive model for an epoxy resin. Multi-temperature relaxation tests on fully and partially cured rectangular epoxy specimens were conducted in a dynamic mechanical analysis apparatus with a three-point bending clamp. Master curves were constructed from the relaxation test results based on the time–temperature superposition hypothesis. The influence of the degree of cure was included through the cure-dependent glass transition temperature which was used as reference temperature for the shift factors. The model parameters were optimized by minimization of the differences between the model predictions and the experimental data. The model predictions were successfully validated against an independent creep-like strain history over which the temperature varied.

Enhancing the toughness of composites via dynamic thiol–thioester exchange (TTE) at the resin–filler interface

2020 ◽  
Vol 11 (29) ◽  
pp. 4760-4767 ◽  
Author(s):  
Nancy Sowan ◽  
Yinan Lu ◽  
Kevin J. Kolb ◽  
Lewis M. Cox ◽  
Rong Long ◽  
...  
Keyword(s):  
Stress Relaxation ◽  
Mechanical Performance ◽  
Interfacial Stress ◽  
Adaptive Interface ◽  
Thioester Exchange

An adaptive interface employing thiol-thioester exchange (TTE) at the resin-filler interface is introduced to promote interfacial stress relaxation and improve the mechanical performance of thermosetting composites.

Development of G-Helix Structure as Off-Chip Interconnect

2004 ◽  
Vol 126 (2) ◽  
pp. 237-246 ◽  
Author(s):  
Qi Zhu ◽  
Lunyu Ma ◽  
Suresh K. Sitaraman
Keyword(s):  
Mechanical Performance ◽  
Coefficient Of Thermal Expansion ◽  
Mechanical Analysis ◽  
Organic Substrate ◽  
Electrical Performance ◽  
Wafer Level ◽  
Wafer Level Packaging ◽  
Package Weight ◽  
Mechanical Compliance ◽  
Cte Mismatch

Microsystem packages continue to demand lower cost, higher reliability, better performance and smaller size. Compliant wafer-level interconnects show great potential for next-generation packaging. G-Helix, an electroplated compliant wafer-level chip-to-substrate interconnect can facilitate wafer-level probing as well as wafer-level packaging without the need for an underfill. The fabrication of the G-Helix interconnect is similar to conventional IC fabrication process and is based on electroplating and photolithography. G-Helix interconnect has good mechanical compliance in the three orthogonal directions and can accommodate the differential displacement induced by the coefficient of thermal expansion (CTE) mismatch between the silicon die and the organic substrate. In this paper, we report the wafer-level fabrication of an area-arrayed G-Helix interconnects. The geometry effect on the mechanical compliance and electrical parasitics of G-Helix interconnects have been studied. Thinner and narrower arcuate beams with larger radius and taller post are found to have better mechanical compliance. However, it is also found that structures with excellent mechanical compliance may not have good electrical performance. Therefore, a trade off is needed. Using response surface methodology (RSM), an optimization has been done. Furthermore, reliability of the optimized G-helix interconnects in a silicon-on-organic substrate assembly has been assessed, which includes the package weight and thermo-mechanical analysis. The pitch size effect on the electrical and mechanical performance of G-Helix interconnects has also been studied.

scholarly journals The Influence of Reclaimed Asphalt Pavement on the Mechanical Performance of Bituminous Mixtures. An Analysis at the Mortar Scale

2020 ◽  
Vol 12 (20) ◽  
pp. 8343
Author(s):  
Ana E. Hidalgo ◽  
Fernando Moreno-Navarro ◽  
Raúl Tauste ◽  
M. Carmen Rubio-Gámez
Keyword(s):  
Mechanical Performance ◽  
Asphalt Pavement ◽  
Mechanical Analysis ◽  
Elastic Response ◽  
Reclaimed Asphalt Pavement ◽  
Reclaimed Asphalt ◽  
Bituminous Mixtures ◽  
Water Sensitivity ◽  
Term Performance

The main characteristics of bituminous mixtures manufactured with a considerable amount of reclaimed asphalt pavement (RAP), compared to conventional mixtures, are a reduction in workability, an increase in stiffness, and a loss of ductility, due to the presence of the aged bitumen contained in the RAP particles. To minimize these impacts, softer binders or rejuvenators are commonly used in the design of these mixtures in order to restore part of the ductility lost and to reduce the stiffness. In spite of previous investigations demonstrating that the mortar plays an essential role in the workability, long-term performance, and durability of bituminous mixtures (where cracking, cohesion, and adhesion problems all start at this scale), not many studies have assessed the impacts caused by the presence of RAP. In response to this, the present paper analyzes the workability, fatigue performance, and water sensitivity of bituminous mortars containing different amounts of RAP (from 0% to 100%) and rejuvenators. Mortar specimens were compacted using a gyratory compactor and studied via dynamic mechanical analysis under three point bending configuration. The results demonstrated that the presence of RAP reduces the workability and ductility of asphalt mortars. However, it also causes an increase in their stiffness, which induces a more elastic response and causes an increase in their resistance to fatigue, which could compensate for the loss of ductility. This aspect, together with the low water sensitivity shown, when using Portland cement as an active filler, would make it possible to produce asphalt materials with high RAP contents with a similar long-term mechanical performance as traditional ones. In addition, the use of rejuvenators was demonstrated to effectively correct the negative workability and ductility impacts caused by using RAP, without affecting the fatigue resistance and material adhesion/cohesion.

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