Progressive fracture in composites subjected to hygrothermal environment

Minnetyan, Levon; Murthy, Pappu L. N.; Chamis, Christos C.

doi:10.2514/6.1991-1140

Cited by 7 publications

(8 citation statements)

References 3 publications

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“…The use of computer-based computational modeling to evaluate the service life (i.e., durability and reliability) of Polymer Matrix Composite (PMC) structures has been under development by NASA Lewis/ Langley [11][12][13][14][15][16] for several years, with the result that computer codes have become available for evaluation of PMC structures under service conditions. The use of computer-based computational modeling to evaluate the service life (i.e., durability and reliability) of Polymer Matrix Composite (PMC) structures has been under development by NASA Lewis/ Langley [11][12][13][14][15][16] for several years, with the result that computer codes have become available for evaluation of PMC structures under service conditions.…”

Section: -14mentioning

confidence: 99%

Risk Management of Composite Structures

Castillo¹,

Shroyer²,

Abdi³

2004

Engineering Design Reliability Handbook

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The two aspects of risk assessment for an event are likelihood of occurrence of the event and the consequence of the event given its occurrence. A typical risk matrix where several events would usually be plotted is shown in Figure 45.1.Composite structures are often used in situations where they are subjected to multiple environments and combined loads. They can fail in a variety of modes, some of which have dire consequences. Knowledge of the risk-likelihood/consequence space is required for proper risk management. For example, space vehicles face combined environment loading that includes dynamic/acoustic/static thermalmechanical loads applied in a wide range of random atmospheric (e.g., hygral) conditions that gradate to the vacuum of space during a mission. These complex conditions and the consequences of possible system failure make risk management to achieve mission-readiness quality both costly and time consuming. This complexity is present to varying degrees in most military and commercial products employing advanced composite designs. Much of the cost and time of assessing/managing risk is due to physical testing. Physical testing is usually done in the design stage to obtain an adequate design and again during production to ensure that the design criteria have been met. Tests that give useful failure information (destructive tests) are usually limited to small portions of a system and a few failure modes. Acceptancetype tests that do not involve failure give minimal information about either the likelihood or consequence of failure for multiple complex loadings and failure mechanisms. The penalty is paid in cost, weight, and quality trade-offs -limited risk management. ProblemThe present method of structural design is based on tailoring structural components and joints to provide the required strength and stiffness response based on finite element stress analyses. Safety factors are -2Engineering Design Reliability Handbook used locally to provide sufficient strength for each component to remain safe under occasional overloading. The factors of safety for each failure mode are usually rules of thumb based on limited experience and test data. The focus is often on local rather than on system considerations. For example, during the initial design phase, the effects of possible local failures due to overloads and discrete source damage are not considered with regard to global structural response and damage tolerance.Addressing combined environments, such as those described for spacecraft, usually involves modifying (increasing) the factors of safety. There is generally little data to define how much to increase the factor of safety. The risk strategy/culture of the enterprise or regulatory agency may drive the decision, or "similar" experience with metals may be used. This drives design risks such as cost and weight that can result in a product that cannot satisfy the customer or market requirements (market failure). Another aspect of the risk is designing products that perform satisfactorily for a require...

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Section: -14mentioning

confidence: 99%

Risk Management of Composite Structures

Castillo¹,

Shroyer²,

Abdi³

2004

Engineering Design Reliability Handbook

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“…Previous researchers predicted the influence of an existing notch, as well as loading on the safety and durability of fiber composite specimens by tracking the damage growth and propagation. Minnetyan et al [2][3][4][5] and Huang et al [6,7] have demonstrated that computational simulations can be used to evaluate the fracture characteristics of composite structures under various loading and environmental conditions. [8] modeled C(T) specimens and identified the damage initiation, growth, and propagation processes for cross-ply laminated specimens.…”

Section: Introductionmentioning

confidence: 99%

“…[8] modeled C(T) specimens and identified the damage initiation, growth, and propagation processes for cross-ply laminated specimens. However, most of the previous investigations [2][3][4][5][6]8] focused on cross-ply and angle-ply laminated composites. Since biaxial braided fiber composites have many advantages over conventional laminated composites and are used frequently in aerospace and automobile components, it is essential to develop an effective computational capability to predict fracture behavior of biaxially braided composites.…”

Section: Introductionmentioning

confidence: 99%

Fracture Propagation in Composites with Biaxial Fiber Reinforcement

Zhao

Minnetyan

Chamis

2004

Journal of Reinforced Plastics and Composites

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Fracture characteristics such as damage progression, work of fracture, ultimate fracture loads, and failure modes are evaluated by computational simulation for composites with biaxial braided fiber reinforcements. Several Graphite-Epoxy Mode I compact tension (C(T)) specimens with different biaxial fiber orientations are modeled and simulated. Damage initiation, growth, and propagation processes at the microscopic level are tracked, enabling a more insightful interpretation of the test results. The effects of ply-layup with various orientations of the braid axis with reference to the notch directions are investigated with respect to their influences on damage and fracture progression characteristics. Results validate the computational simulation method and identify fracture characteristics for biaxially reinforced composites.KEY WORDS: braided composite, C(T) specimen, notch angle, computational simulation, fracture characteristics.

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“…The present computational approach has previously been used for the investigation of the behavior of conventional laminated composite structures, including the effects of composite degradation on structural response (Minnetyan et al, 1992), composite structures global fracture toughness (Minnetyan et al, 1990), effect of the hygrothermal environment on durability (Minnetyan et al, 1992a), damage progression in stiffened composite shells (Minnetyan et al, 1992b), the behavior of discontinuously stiffened composite panels under loading (Minnetyan et al, 1995), damage propagation in thick composite shells under external pressure (Minnetyan and Chamis, 1997), damage and fracture progression in CFRP I-beams with three different lay-ups (Huang and Minnetyan, 1998). Further degradation is in the form of additional cracking, delamination, and fiber fractures that may lead to structural fracture.…”

Section: Introductionmentioning

confidence: 99%

Progressive Fracture of Stitched Stiffened Composite Shear Panels in the Postbuckling Range

Huang

Minnetyan

2001

Journal of Reinforced Plastics and Composites

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Progressive damage and fracture of stitched J-stiffened composite panels under shear loading is evaluated via computational simulation. The objective of this paper is to demonstrate the postbuckling range application of a new methodology that scales up constituent material properties, stress and strain limits to the structure level, to evaluate the overall damage and fracture propagation for stitched laminates. Stiffened panels with different lay-up configurations are simulated for various damage stages, including damage initiation, growth, accumulation, and progression to fracture. Postbuckling analysis is also included to evaluate progressive fracture characteristics after local buckling of the skin. Results are compared with experimental data from the literature.

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Progressive fracture in composites subjected to hygrothermal environment

Abstract: The influence of hygrothermal environmental conditions on the load carrying ability and response of composite structures

Cited by 7 publications

References 3 publications

Risk Management of Composite Structures

Risk Management of Composite Structures

Fracture Propagation in Composites with Biaxial Fiber Reinforcement

Progressive Fracture of Stitched Stiffened Composite Shear Panels in the Postbuckling Range

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