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Autoclave Molding

The Experts below are selected from a list of 231 Experts worldwide ranked by ideXlab platform

Uday K. Vaidya – 1st expert on this subject based on the ideXlab platform

  • Affordable processing of thick section and integral multi-functional composites
    Composites – Part A: Applied Science and Manufacturing, 2001
    Co-Authors: Uday K. Vaidya, A. Abraham, Sachin Bhide

    Abstract:

    The use of multi-functional integral armor is of current interest in armored vehicles and military carriers. In the present study, thick-section laminated composites and multi-layered integrated composites have been processed/manufactured with the aim of providing multi-functionality including easy reparability, quick deployment, enhanced ballistic damage and fire protection, as well as lightweight advantages. The design of an integral armor utilizes a combination of thick-section structural composite, ceramic tiles, resilient rubber, fire retardant laminate liner and a composite durability cover. Processing techniques such as automated fiber placement and/or Autoclave Molding are traditionally used to process dissimilar multi-layered structure, but prove to be expensive. This work focuses on emerging cost-effective liquid Molding processes such as vacuum assisted resin transfer/infusion Molding (VARTM) for the production of thick-section and integral armor parts (up to 50 mm thick). While thick-section composites have applications in a variety of structures including armored vehicles, marine bodies, civil infrastructure, etc. in the present work they refer to the structural laminate within the integral armor. The processing steps of thick-section composite panels and integral armor have been presented. The integrity of the interfaces has been evaluated through scanning electron microscopy (SEM). Representative results on static and dynamic response (high strain rate, HSR and ballistic impact) of the VARTM processed thick-section composite panels are presented. Wherever applicable, comparisons are made to conventional closed-mold resin transfer Molding (CMRTM). Process sensing by way of flow and cure monitoring of the resin in the fiber perform has been conducted using embedded direct current (DC)-based sensors in the thick-section preform and integral armor interfaces. The feasibility of cost-effective VARTM for producing thick-section composites and integral armor has been demonstrated. © 2001 Elsevier Science Ltd.

  • Assessment of flow and cure monitoring using direct current and alternating current sensing in vacuum-assisted resin transfer Molding
    Smart Materials and Structures, 2000
    Co-Authors: Uday K. Vaidya, Nitesh C. Jadhav, Madhusoodan V. Hosur, J W Gillespie, Bruce K Fink

    Abstract:

    Vacuum-assisted resin transfer Molding (VARTM) is an emerging manufacturing technique that holds promise as an affordable alternative to traditional Autoclave Molding and automated fiber placement for producing large-scale structural parts. In VARTM, the fibrous preform is laid on a single-sided tool, which is then bagged along with the infusion and vacuum lines. The resin is then infused through the preform, which causes simultaneous wetting in its in-plane and transverse directions. An effective sensing technique is essential so that comprehensive information pertaining to the wetting of the preform, arrival of resin at various locations, cure gradients associated with thickness and presence of dry spots may be monitored. In the current work, direct current (dc) and alternating current sensing/monitoring techniques were adopted for developing a systematic understanding of the resin position and cure on plain weave S2-glass preforms with Dow Derakane vinyl ester VE 411-350, Shell EPON RSL 2704/2705 and Si-AN epoxy as the matrix systems. A SMARTweave dc sensing system was utilized to conduct parametric studies: (a) to compare the flow and cure of resin through the stitched and non-stitched preforms; (b) to investigate the influence of sensor positioning, i.e. top, middle and bottom layers; and (c) to investigate the influence of positioning of the process accessories, i.e. resin infusion point and vacuum point on the composite panel. The SMARTweave system was found to be sensitive to all the parametric variations introduced in the study. Furthermore, the results obtained from the SMARTweave system were compared to the cure monitoring studies conducted by using embedded interdigitated (IDEX) dielectric sensors. The results indicate that SMARTweave sensing was a viable alternative to obtaining resin position and cure, and was more superior in terms of obtaining global information, in contrast to the localized dielectric sensing approach.

  • Assessment of flow and cure monitoring using direct current and alternating current sensing in Vacuum Assisted Resin Transfer Molding
    American Society of Mechanical Engineers Manufacturing Engineering Division MED, 1999
    Co-Authors: Nitesh C. Jadhav, Uday K. Vaidya, Madhusoodan V. Hosur, J W Gillespie, Bruce K Fink

    Abstract:

    Vacuum Assisted Resin Transfer Molding (VARTM) is an emerging manufacturing technique that holds promise as an affordable alternative to traditional Autoclave Molding and automated fiber placement for producing large scale structural parts. In VARTM, the fibrous preform is laid on a single sided tool, which is then bagged along with the infusion and vacuum lines. The resin is then infused through the preform, which causes simultaneous wetting in its in-plane and transverse directions. An effective sensing technique is essential so that comprehensive information pertaining to the wetting of the preform, arrival of resin at various locations, cure gradients associated with thickness and presence of dry spots may be monitored. In the current work, direct current and alternating current sensing/monitoring techniques were adopted for developing a systematic understanding of resin position and cure on plain weave S2-Glass preforms with Dow Derakane vinyl ester VE 411-350, Shell EPON RSL 2704/2705 and Si-AN epoxy as the matrix systems. The SMARTweave DC sensing system was utilized to conduct parametric studies a) to compare the flow and cure of resin through the stitched and non-stitched preforms, b) influence of sensor positioning, i.e., top, middle and bottom layers, c) influence of positioning of the process accessories, i.e., resin infusion point and vacuum point on the composite panel. The SMARTweave system was found to be sensitive to all the parametric variations introduced in the study. Furthermore, the results obtained from the SMARTweave system were compared to the cure monitored from embedded IDEX dielectric sensors. The results indicate that SMARTweave sensing was a viable alternative to obtaining resin position and cure, and more superior in terms of obtaining global information in contrast to the localized dielectric sensing approach.

Bruce K Fink – 2nd expert on this subject based on the ideXlab platform

  • Assessment of flow and cure monitoring using direct current and alternating current sensing in vacuum-assisted resin transfer Molding
    Smart Materials and Structures, 2000
    Co-Authors: Uday K. Vaidya, Nitesh C. Jadhav, Madhusoodan V. Hosur, J W Gillespie, Bruce K Fink

    Abstract:

    Vacuum-assisted resin transfer Molding (VARTM) is an emerging manufacturing technique that holds promise as an affordable alternative to traditional Autoclave Molding and automated fiber placement for producing large-scale structural parts. In VARTM, the fibrous preform is laid on a single-sided tool, which is then bagged along with the infusion and vacuum lines. The resin is then infused through the preform, which causes simultaneous wetting in its in-plane and transverse directions. An effective sensing technique is essential so that comprehensive information pertaining to the wetting of the preform, arrival of resin at various locations, cure gradients associated with thickness and presence of dry spots may be monitored. In the current work, direct current (dc) and alternating current sensing/monitoring techniques were adopted for developing a systematic understanding of the resin position and cure on plain weave S2-glass preforms with Dow Derakane vinyl ester VE 411-350, Shell EPON RSL 2704/2705 and Si-AN epoxy as the matrix systems. A SMARTweave dc sensing system was utilized to conduct parametric studies: (a) to compare the flow and cure of resin through the stitched and non-stitched preforms; (b) to investigate the influence of sensor positioning, i.e. top, middle and bottom layers; and (c) to investigate the influence of positioning of the process accessories, i.e. resin infusion point and vacuum point on the composite panel. The SMARTweave system was found to be sensitive to all the parametric variations introduced in the study. Furthermore, the results obtained from the SMARTweave system were compared to the cure monitoring studies conducted by using embedded interdigitated (IDEX) dielectric sensors. The results indicate that SMARTweave sensing was a viable alternative to obtaining resin position and cure, and was more superior in terms of obtaining global information, in contrast to the localized dielectric sensing approach.

  • Assessment of flow and cure monitoring using direct current and alternating current sensing in Vacuum Assisted Resin Transfer Molding
    American Society of Mechanical Engineers Manufacturing Engineering Division MED, 1999
    Co-Authors: Nitesh C. Jadhav, Uday K. Vaidya, Madhusoodan V. Hosur, J W Gillespie, Bruce K Fink

    Abstract:

    Vacuum Assisted Resin Transfer Molding (VARTM) is an emerging manufacturing technique that holds promise as an affordable alternative to traditional Autoclave Molding and automated fiber placement for producing large scale structural parts. In VARTM, the fibrous preform is laid on a single sided tool, which is then bagged along with the infusion and vacuum lines. The resin is then infused through the preform, which causes simultaneous wetting in its in-plane and transverse directions. An effective sensing technique is essential so that comprehensive information pertaining to the wetting of the preform, arrival of resin at various locations, cure gradients associated with thickness and presence of dry spots may be monitored. In the current work, direct current and alternating current sensing/monitoring techniques were adopted for developing a systematic understanding of resin position and cure on plain weave S2-Glass preforms with Dow Derakane vinyl ester VE 411-350, Shell EPON RSL 2704/2705 and Si-AN epoxy as the matrix systems. The SMARTweave DC sensing system was utilized to conduct parametric studies a) to compare the flow and cure of resin through the stitched and non-stitched preforms, b) influence of sensor positioning, i.e., top, middle and bottom layers, c) influence of positioning of the process accessories, i.e., resin infusion point and vacuum point on the composite panel. The SMARTweave system was found to be sensitive to all the parametric variations introduced in the study. Furthermore, the results obtained from the SMARTweave system were compared to the cure monitored from embedded IDEX dielectric sensors. The results indicate that SMARTweave sensing was a viable alternative to obtaining resin position and cure, and more superior in terms of obtaining global information in contrast to the localized dielectric sensing approach.

Ramesh Chandra – 3rd expert on this subject based on the ideXlab platform

  • Active shape control of composite blades using shape memory actuation
    Smart Materials and Structures, 2001
    Co-Authors: Ramesh Chandra

    Abstract:

    This paper presents active shape control of composite beams using shape memory actuation. Shape memory alloy (SMA) bender elements trained to memorize bending shape were used to induce bending and twisting deformations in composite beams. Bending-torsion coupled graphite-epoxy and kevlar-epoxy composite beams with Teflon inserts were manufactured using an AutoclaveMolding technique. Teflon inserts were replaced by trained SMA bender elements. Composite beams with SMA bender elements were activated by heating these using electrical resistive heating and the bending and twisting deformations of the beams were measured using a mirror and laser system. The structural response of the composite beams activated by SMA elements was predicted using the Vlasov theory, where these beams were modeled as open sections with many branches. The bending moment induced by a SMA bender element was calculated from its experimentally determined memorized shape. The bending, torsion, and bending-torsion coupling stiffness coefficients of these beams were obtained using analytical formulation of an open-section composite beam with many branches (Vlasov theory).

  • Shape memory alloy actuation for active tuning of composite beams
    Smart Materials and Structures, 1997
    Co-Authors: Jeanette J. Epps, Ramesh Chandra

    Abstract:

    This paper presents an experimental – analytical study on the active tuning of composite beams using shape memory alloy (SMA) wires. Two graphite – epoxy composite beams with embedded fused silica tubes (also called sleeves) with `dummy’ steel wires inserted in the sleeves were manufactured using an Autoclave Molding technique. After curing, the `dummy’ wires were replaced by pre-strained SMA wires. During testing of such a beam, the beam and SMA wire are independently clamped at both ends and the SMA wires are activated using electrical resistive heating. A large tensile recovery force develops in the wires due to a phase transformation and the mechanical constraints provided by the clamps. The influence of this recovery force on the vibration behavior of the composite beams was determined by vibration testing. Analytically, these beams with SMA wires inserted in embedded sleeves were examined as beams on an elastic foundation; the spring constant of the elastic foundation depended on the axial recovery force of the SMA wire. Good correlation between analysis and experiment was achieved. A numerical parametric study of natural frequencies of composite beams with activated SMA wires was conducted. The parameters considered were the diameter and the number of SMA wires. The numerical study suggests that inserting 25 SMA wires of 20 mils diameter into a graphite – epoxy beam of 30 in length, 1 in width and 62 mils thickness increases its first frequency by 276%.

  • Torsional actuation with extension-torsion composite coupling and a magnetostrictive actuator
    AIAA Journal, 1995
    Co-Authors: Christopher M. Bothwell, Ramesh Chandra, Inderjit Chopra

    Abstract:

    This paper presents an analytical-experimental study of using magnetostrictive actuators in conjunction with an extension-torsion coupled composite tube to actuate a rotor blade trailing-edge flap to actively control helicopter vibration. Thin-walled beam analysis based on Vlasov theory was used to predict the induced twist and extension in a composite tube with magnetostrictive actuation. To validate the analysis, extension-torsion coupled Kevlar®-epoxy tubes or different ply lay-ups were fabricated using an Autoclave Molding technique. They tubes were first tested under static mechanical loads, and tip twist and axial extension were measured by means or a laser optical system and strain gages, respectively. Good correlation between theory and experiment was achieved. Subsequently, these composite tubes were tested under magnetostrictive actuation. The [11] 2 Kevlar-epoxy tube system generated the maximum twist, 0.19 deg in tension and 0.20 deg in compression. The Kevlar-epoxy systems showed good correlation between measured and predicted twist values. Finally, alternate actuator concepts for these tubes, specifically piezoelectric stacks and electrostrictive actuators, were examined, and a piezoelectric stack actuator was round to induce much larger force and twist (approximately 3 times that created by the magnetostrictive actuator/tube system)