Now showing items 1-20 of 37

    • Additive manufactured polymer test coupons: Issues and solutions 

      Andrulonis, Rachael; Lovingfoss, Royal; Tomblin, John S. (ASTM International, 2020-06-04)
      Leveraging the experience and lessons learned from the National Center for Advanced Material Performance (NCAMP) and the Composite Materials Handbook-17 (CMH-17) composite material databases, a new qualification program ...
    • Allowable generation and generic basis value for multiple loading and environmental conditions 

      Hajiha, Reza; Godines, Cody; De Fenza, De Fenza, Angelo; Baid, Harsh Kumar; Clarkson, Elizabeth P.; Moazami, Nima; Abdi, Frank (CAMX, 2020)
      Engineers conduct expensive testing in different environmental conditions to obtain the necessary material allowables. These values consider scatter in composite material constituents and structure according to the “Building ...
    • Automated fiber placement (AFP)--Effects of features and defects 

      Seneviratne, Waruna P.; Tomblin, John S.; Shafie, Mohamed Z.; Perera, Shenal; Smith, Garret (DEStech Publications, 2019-09)
      Automated Fiber Placement (AFP) manufacturing methods, considered to be one of the most advanced methods of composite manufacturing, are used in fabricating complex and large scale composite structures. During AFP ...
    • Automated fiber placement (AFP)—Effects of features and defects 

      Seneviratne, Waruna P.; Tomblin, John S.; Shafie, Mohamed Z.; Perera, Shenal; Smith, Garret (DEStech Publications, 2019)
      Automated Fiber Placement (AFP) manufacturing methods, considered to be one of the most advanced methods of composite manufacturing, are used in fabricating complex and large scale composite structures. During AFP ...
    • Automating structural modeling of composites enriched by X-ray micro-tomography and digital imaging data 

      Iliopoulos, Athanasios P.; Michopoulos, John G.; Steuben, John C.; Birnbaum, Andrew J.; Lua, Jim Y.; Karuppiah, Anand Vijay; Seneviratne, Waruna P.; Saathoff, Caleb (ASME, 2018)
      The manufacturing processes of Fiber Reinforced Polymers (FRPs) as composite materials are frequently prone to the creation of various types of undesired morphologies and defects. These can include layer waviness, inclusions, ...
    • A combined X-Ray CT and mechanistic characterization of bearing failure mechanisms in bolted composite components 

      Cui, Xiaodong; Xiao, Jian; Lua, Jim Y.; Kariyawasam, Supun; Fulghum, Ethan; Saathoff, Caleb (Vertical Flight Society, 2021-05)
      This paper presents the characterization of bearing failure mechanisms in composite joints with countersunk bolt by applying an X-ray Computed Tomography (XCT) technique and a developed bearing failure model to build the ...
    • Composite drilling characterization and performance evaluation 

      Xiao, Jian; Pham, Dinh Chi; Lua, Jim Y.; Saathoff, Caleb; Seneviratne, Waruna P. (DEStech Publications, 2019-09)
      Hole drilling is one of the most widely used operations in order to place bolts or rivets. Drilling holes in composites leads to drilling-induced defects and damages such as delamination, burr, microcracking, swelling, ...
    • Compressive response of composite laminates with defects 

      Cui, Xiaodong; Karuppiah, Anand Vijay; Pham, Dinh Chi; Lua, Jim Y.; Saathoff, Caleb; Seneviratne, Waruna P. (American Institute of Aeronautics and Astronautics Inc, 2020-01-05)
      Defects are inevitable in the manufacture and service of composite laminates and their influence on the mechanical performance of composite laminates can be substantial. Ply waviness and delamination are two major types ...
    • Coupon-level mechanical testing for polymer-based additive manufacturing 

      Park, Chul Y.; Rupel, Keith E.; Henry, Chelsey E.; Palliyaguru, Upul R. (ASTM International, 2020-06-04)
      The term additive manufacturing (AM) is used to describe processes of joining materials to make parts from a three-dimensional model data, as opposed to subtractive manufacturing. Although AM technology offers potential ...
    • Crashworthiness by analysis: verifying FEA modeling capabilities by accident reconstruction 

      Zinzuwadia, Chandresh M.; Olivares, Gerardo; Ly, Hoa T.; Gomez Valbuena, Luis M. (ASCE, 2018-11-15)
      A finite element (FE) model of a generic single-aisle narrow body transport aircraft was used for computational crash analysis to compare simulated deformations to those observed in the Turkish Airline Flight 1951 crash ...
    • Damage growth analysis of sandwich structures subjected to combined compression and pressure loading 

      Seneviratne, Waruna P.; Tomblin, John S.; Perera, Shenal; Varatharaj, Pirashandan (DEStech Publications, 2019-09)
      Fluid-ingression phenomena in composite sandwich structures is a concern for components employed in the aerospace industry. Poor design/material selections, impact damages, thermo-mechanical loads occurring during ...
    • Damage mechanisms in tapered composite structures under static and fatigue loading 

      Rao, Prabhakar M.; Gurvich, Mark R.; Palliyaguru, Upul R.; Seneviratne, Waruna P. (DEStech Publications, 2019-09)
      In this work an integrated computational/experimental approach was developed to validate the predictive capabilities of State-of-the-Art (SoA) Progressive Damage Analysis (PDA) methods and tools. Specifically, a tapered ...
    • Defects characterization and evaluation of their effects on compressive failure of composite components 

      Cui, Xiaodong; Pham, Dinh Chi; Karuppiah, Anand Vijay; Lua, Jim Y.; Saathoff, Caleb; Seneviratne, Waruna P. (DEStech Publications, 2019-09)
      In the design and certification of composite structural components for aircrafts, compression and combined compression and shear loading cases have to be considered. Various forms of defects such as ply waviness, delamination ...
    • Defects characterization, damage mapping, and property evaluation of composites 

      Lua, Jim Y.; Sadeghirad, Alireza; Cui, Xiaodong; Karuppiah, Anand Vijay; Saathoff, Caleb; Seneviratne, Waruna P. (DEStech Publications Inc., 2018)
      The presence of voids in the composite laminates can reduce the mechanical properties in composites and these voids can become precursors in the activation of other failure modes such as delamination. Knowing the volume ...
    • Electroplating polymer based additive manufactured parts for enhanced structural performance 

      Seneviratne, Waruna P.; Tomblin, John S.; Saathoff, Brandon L. (DEStech Publications, 2021)
      Additive manufacturing has been adopted in many aerospace and defense applications to reduce weight and buy-to-fly ratios of low-volume high- complexity parts. Polymer-based additive manufacturing processes such as Fused ...
    • An engineering approach to analyze damage initiation modes in tapered composite structures 

      Rao, Prabhakar M.; Palliyaguru, Upul R.; Gurvish, Mark R.; Seneviratne, Waruna P. (DEStech Publications Inc., 2018)
      In this work an engineering approach is demonstrated for analyzing damage initiation modes in tapered composite structures. The analysis methodology includes simulation of the non-linear static response of tapered composite ...
    • Evaluation of ls-dyna mat162 for modeling composite fastener joints for high rates of loading 

      Kona Ravi, Aswini; Bhasin, Akhil; Gomez, Leandro; Olivares, Gerardo; Gomez, Adrian; Keshavanarayana, Suresh R.; Pang, Jenna K.; Molitor, Matthew; Rassaian, Mostafa (American Institute of Aeronautics and Astronautics Inc., 2019-01)
      In the present work, the behavior of composite-fastener joints in bearing failure at dynamic stroke rates of 500 in/s, 300 in/s and 100 in/s has been evaluated through progressive damage analysis (PDA) material model in ...
    • Experimental Observations of Damage States in Unnotched and Notched 3D Orthogonal Woven Coupons Loaded in Tension 

      Jackson, Wade C.; Bergan, Andrew C.; Rose, Cheryl A.; Segal, Kenneth N.; Gardner, Nathaniel W.; Waas, Nalinda W. (American Institute of Aeronautics and Astronautics, 2021-12-29)
      This paper describes a series of unnotched and notched tensile tests on two 3D orthogonal woven architectures loaded in the warp direction. Dogbone specimens were used for the unnotched tests, and open-hole specimens were ...
    • Fatigue damage modeling in laminated composites by using Rx-FEM and strength tracking method 

      Lu, Weitsen; Gao, Zhenjia; Adluru, Hari K.; Hoos, Kevin H.; Seneviratne, Waruna P.; Mollenhauer, David H.; Iarve, Endel V. (DEStech Publications, 2021-09)
      The durability and residual load carrying capacity of composite materials and structures is of critical importance for increasing their application across the industry. Regularized eXtended Finite Element Method (Rx-FEM) ...
    • High rate testing of composite fastener joints with and without clamp-up 

      Gomez, Adrian; Keshavanarayana, Suresh R.; Castillo, Luis D.; Kona Ravi, Aswini; Bhasin, Akhil; Pang, Jenna K.; Molitor, Matthew; Rassaian, Mostafa (DEStech Publications Inc., 2018)
      The NASA Advanced Composites Consortium (ACC) High Energy Dynamic Impact (HEDI) group has been investigating experimentally the effects of testing speed and fastener clamp-up on the behavior of single lap shear composite ...