A New Method to Reduce Cure-Induced Stresses in Thermoset Polymer Composites, Part I: Test Method

Madhukar, Madhu S.; Genidy, A. N. D. Mohamed S.; Russell, John D.

doi:10.1106/hucy-dy2b-2n42-ujbx

Cited by 42 publications

(29 citation statements)

References 12 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The sources of the cure induced strain are chemical shrinkage, the result of crosslinking, and thermal deformation due to a reduction in temperature [1,2]. Over the years, several experimental methods have been developed for measuring both chemical and thermal shrinkage.…”

Section: Introductionmentioning

confidence: 99%

Digital image correlation measurement of resin chemical and thermal shrinkage after gelation

Kravchenko

Casares

2015

J Mater Sci

View full text Add to dashboard Cite

A method for measuring chemical shrinkage and coefficient of thermal expansion during cure and postgelation is presented based on digital image correlation to record the in situ stress-free strain field in a thermosetting polymer. An independent determination of the resin cure kinetics was required to relate the chemical shrinkage strain and coefficient of thermal expansion to the degree of cure. The changes in the coefficient of thermal expansion were observed from the initial heating to final cooling of the sample. The results obtained are shown to compare favorably with results previously found by other techniques. The proposed method provides a simple and reliable procedure to measure the evolution of thermochemical shrinkage properties of the resin during the cure cycle.

show abstract

Section: Introductionmentioning

confidence: 99%

Digital image correlation measurement of resin chemical and thermal shrinkage after gelation

Kravchenko

Casares

2015

J Mater Sci

View full text Add to dashboard Cite

show abstract

“…The manufacturer recommended one-hold cure cycle for HexPly M65 simulated by RAVEN.TimeTemperature, TgDegree of CureAs shown in other studies[Madhukar et al, 2000, White and Hahn, 1993and Li et al, 2014…”

mentioning

confidence: 88%

Integrated Computational Materials Engineering for Airframe Composite Structure Applications

Engelstad

Koon

Action

et al. 2015

56th AIAA/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference

View full text Add to dashboard Cite

IntroductionIntegrated Computational Materials Engineering (ICME) is a game-changing AFRL and industry vision to reduce the material and process development cycle time and cost, simultaneously bringing optimized material systems to the war fighter tailored to the needs of both the airframe and propulsion systems [Ref: National Materials Advisory Board]. The nearterm path to achieving these goals is through integration of material modeling capabilities. AFRL is currently working on two Foundational Engineering Problems (FEPs), one for metallic aircraft applications, and one for composites. GE Aviation and Lockheed Martin Aeronautics (LM Aero) have teamed to work the composites FEP, called "Integrated Computational Methods for Composite Materials (ICM2)" specifically targeting integration of composites processing, micromechanics, and damage progression modeling codes to address composite material development and application issues. GE is focused on engine applications, whereas LM Aero is focused on airframe applications.For the airframe specific ICM2 FEP, LM Aero is targeting the fundamental issues that drive the design of acreage composite materials on the next generation airframes. In order to meet composite airframe future needs, large scale airframe manufacturing will target larger, unitized composite assemblies with increased use of bonding and reduced part-count. Process automation will be utilized to reduce costs through reductions in touch labor. Improvements in composite design allowables are critical to optimal airframe weight (and hence performance) and must be obtained through use of higher performance resins and fibers along with reduced variability in key sizing properties. The ICM2 program intends to integrate composite process and design modeling codes to streamline the development cycle time and reduce the cost to implement such new high performance materials on next generation aircraft. For the ICM2 program's demonstration purposes LM Aero is studying the IM7/M65 bismaleimide (BMI) system for application to large acreage wing skin and web applications. M65 is an established BMI system (MRL ≥5) well suited to manufacturing using high speed automated fiber placement (AFP).BMI systems have experienced increased usage on fighter aircraft due primarily to key structural design properties such as open hole compression (OHC) and compression-strengthafter-impact (CSAI), the values for which exceed epoxies at max service temperature and moisture conditions [Rousseau et al.] These key properties often "size" the acreage of the aircraft composite skins. Bolted joint strength and acreage repair criteria are most closely related

show abstract

“…After demolding, the composite is usually post-cured at an elevated temperature above T g . During this process, the stresses induced by curing can be significantly relaxed [24][25][26]. For some resin systems, such as epoxy, the curing strain during conversion can be neglected in the analysis of residual stress [27].…”

Section: Spring-in Modelmentioning

confidence: 99%

Modeling the process-induced dimensional variations of general curved composite components and assemblies

Dong¹

2009

Composites Part A: Applied Science and Manufacturing

View full text Add to dashboard Cite

Dimensional variations are induced during the processing of composite materials. General curved components are commonly used in composite structures. Their performance is affected by the dimensional variations associated with the manufacturing process. This paper presents a piecewise approach for predicting the dimensional variations of general curved composite components and assemblies. For a general curved composite component, it is first divided into a number of pieces of simple geometry. For each piece, the dimensional variation, i.e. spring-in, is calculated using the effective coefficients of thermal expansion. Based on the dimensional variation of each piece, the dimensional variations of the general curved component are calculated sequentially. This approach was validated against the finite element analysis. It shows that it offers excellent accuracy while avoiding time-consuming numerical computations. Besides general curved components, this approach can also be applied to composite assemblies. It provides the foundation for the tolerance analysis/synthesis of composites.

show abstract

A New Method to Reduce Cure-Induced Stresses in Thermoset Polymer Composites, Part I: Test Method

Cited by 42 publications

References 12 publications

Digital image correlation measurement of resin chemical and thermal shrinkage after gelation

Digital image correlation measurement of resin chemical and thermal shrinkage after gelation

Integrated Computational Materials Engineering for Airframe Composite Structure Applications

Modeling the process-induced dimensional variations of general curved composite components and assemblies

Contact Info

Product

Resources

About