Professor Tsai's research interest is in the development of design methodology of composite materials and structures. As an emerging technology, composite materials offer unique performances for structures that combine light weight with durability. Keys to the successful utilization of composite materials are predictability in performance and cost effective design of anisotropic, laminated structures. Current emphasis is placed on the understanding of failure modes, and computer simulation for design and cost estimation.

Academic Appointments

Boards, Advisory Committees, Professional Organizations

  • Member, National Academy of Engineering (1995 - Present)

All Publications

  • Happy 40th anniversary JOURNAL OF COMPOSITE MATERIALS Tsai, S. W. 2008; 42 (18): 1821-1823
  • Smart cure of thick composite filament wound structures to minimize the development of residual stresses EUROMECH 453 Colloquium on Internal Stresses in Polymer Composite Processing and Service Life Lee, D. H., Kim, S. K., Lee, W. I., Ha, S. K., Tsai, S. W. ELSEVIER SCI LTD. 2006: 530–37
  • Three decades of composites activities at US Air Force Materials Laboratory COMPOSITES SCIENCE AND TECHNOLOGY Tsai, S. W. 2005; 65 (15-16): 2295-2299
  • Prediction of fatigue S-N curves of composite laminates by Super Mic-Mac COMPOSITES PART A-APPLIED SCIENCE AND MANUFACTURING Sihn, S., Tsai, S. W. 2005; 36 (10): 1381-1388
  • Trends in the design, manufacture and evaluation of wind turbine blades WIND ENERGY Veers, P. S., Ashwill, T. D., Sutherland, H. J., Laird, D. L., Lobitz, D. W., Griffin, D. A., Mandell, J. F., Musial, W. D., Jackson, K., Zuteck, M., Miravete, A., Tsai, S. W., Richmond, J. L. 2003; 6 (3): 245-259

    View details for DOI 10.1002/we.90

    View details for Web of Science ID 000186355900005

  • Prediction of fatigue life for CFRP/metal bolted joint under temperature conditions JSME/ASME International Conference on Materials and Processing Sekine, N., Nakada, M., Miyano, Y., Kuraishi, A., Tsai, S. W. JAPAN SOC MECHANICAL ENGINEERS. 2003: 484–89
  • Catalysis, specificity, and ACP docking site of Streptomyces coelicolor malonyl-CoA : ACP transacylase STRUCTURE Keatinge-Clay, A. T., Shelat, A. A., Savage, D. F., Tsai, S. C., Miercke, L. J., O'Connell, J. D., Khosla, C., Stroud, R. M. 2003; 11 (2): 147-154


    Malonyl-CoA:ACP transacylase (MAT), the fabD gene product of Streptomyces coelicolor A3(2), participates in both fatty acid and polyketide synthesis pathways, transferring malonyl groups that are used as extender units in chain growth from malonyl-CoA to pathway-specific acyl carrier proteins (ACPs). Here, the 2.0 A structure reveals an invariant arginine bound to an acetate that mimics the malonyl carboxylate and helps define the extender unit binding site. Catalysis may only occur when the oxyanion hole is formed through substrate binding, preventing hydrolysis of the acyl-enzyme intermediate. Macromolecular docking simulations with actinorhodin ACP suggest that the majority of the ACP docking surface is formed by a helical flap. These results should help to engineer polyketide synthases (PKSs) that produce novel polyketides.

    View details for Web of Science ID 000180905000006

    View details for PubMedID 12575934

  • Time- and temperature-dependent failures of a metal-to-composites bonded joint with PMMA adhesive material JOURNAL OF COMPOSITE MATERIALS Sihn, S., Miyano, Y., Nakada, M., Tsai, S. W. 2003; 37 (1): 35-54
  • Interlocked composite grids design and manufacturing JOURNAL OF COMPOSITE MATERIALS Han, D. Y., Tsai, S. W. 2003; 37 (4): 287-316
  • Expression, site-directed mutagenesis, and steady state kinetic analysis of the terminal thioesterase domain of the methymycin/picromycin polyketide synthase BIOCHEMISTRY Lu, H. X., Tsai, S. C., Khosla, C., Cane, D. E. 2002; 41 (42): 12590-12597


    The thioesterase (TE) domain of the methymycin/picromycin synthase (PICS) was functionally expressed in Escherichia coli, and the optimal N-terminal boundary of the recombinant TE was determined. A series of diketide-N-acetylcysteamine (SNAC) thioesters were tested as substrates. PICS TE showed a strong preference for the 2-methyl-3-ketopentanoyl-SNAC substrate 5 over the stereoisomers of the reduced diketides 1-4, with an approximately 1.6:1 preference for the (2R,3S)-2-methyl-3-hydroxy diastereomer 2 over the (2S,3R)-diketide 1. The closely related DEBS TE, the thioesterase from the 6-deoxyerythronolide B synthase, showed a more marked 4.4:1 preference for 2 over 1, with only a slightly greater preference for the 3-ketoacyl-SNAC substrate 5. The roles of several active site residues in PICS TE were examined by site-directed mutagenesis. Serine 148, which is part of the apparent catalytic triad consisting of S148, H268, and D176, was found to be essential for thioesterase activity, while replacement of D176 with asparagine (D176N) gave a mutant thioesterase that retained substantial, albeit reduced, hydrolytic activity toward diketide-SNAC substrates. Mutation of E187 and R191, each of which is thought to play a role in substrate binding, had only minor effects on the relative specificity for diketide substrates 1, 2, and 5. Finally, when PICS TE was fused to the C-terminus of DEBS module 3, the resultant chimeric protein converted diketide 1 with methylmalonyl-CoA to triketide ketolactone 6 with improved catalytic efficiency compared to that of the previously developed DEBS module 3-(DEBS)TE construct.

    View details for DOI 10.1021/bi026006d

    View details for Web of Science ID 000178694000004

    View details for PubMedID 12379101

  • Insights into channel architecture and substrate specificity from crystal structures of two macrocycle-forming thioesterases of modular polyketide synthases BIOCHEMISTRY Tsai, S. C., Lu, H. X., Cane, D. E., Khosla, C., Stroud, R. M. 2002; 41 (42): 12598-12606


    Modular polyketide synthases (PKSs) synthesize the polyketide cores of pharmacologically important natural products such as erythromycin and picromycin. Understanding PKSs at high resolution could present new opportunities for chemoenzymatic synthesis of complex molecules. The crystal structures of macrocycle-forming thioesterase (TE) domains from the picromycin synthase (PICS) and 6-deoxyerythronolide B synthase (DEBS) were determined to 1.8-3.0 A with an R(crys) of 19.2-24.4%, including three structures of PICS TE (crystallized at pH 7.6, 8.0, and 8.4) and a second crystal form of DEBS TE. As predicted by the previous work on DEBS TE [Tsai, S. C., et al. (2001) Proc. Natl. Acad. Sci. U.S.A. 98, 14808-14813], PICS TE contains an open substrate channel and a hydrophobic dimer interface. Notwithstanding their similarity, the dimer interfaces and substrate channels of DEBS TE and PICS TE reveal key differences. The structural basis for the divergent substrate specificities of DEBS TE and PICS TE is analyzed. The size of the substrate channel increases with increasing pH, presumably due to electrostatic repulsion in the channel at elevated pH. Together, these structures support previous predictions that macrocycle-forming thioesterases from PKSs share the same protein fold, an open substrate channel, a similar catalytic mechanism, and a hydrophobic dimer interface. They also provide a basis for the design of enzymes capable of catalyzing regioselective macrocyclization of natural or synthetic substrates. A series of high-resolution snapshots of a protein channel at different pHs is presented alongside analysis of channel residues, which could help in the redesign of the protein channel architecture.

    View details for DOI 10.1021/bi0260177

    View details for Web of Science ID 000178694000005

    View details for PubMedID 12379102

  • Treatment of detrusor-sphincter dyssynergia by pudendal nerve block in patients with spinal cord injury ARCHIVES OF PHYSICAL MEDICINE AND REHABILITATION Tsai, S. J., Lew, H. L., Date, E., Bih, L. I. 2002; 83 (5): 714-717


    To study the effects of pudendal nerve block with phenol on detrusor-sphincter dyssynergia in patients with spinal cord injury (SCI).Before-after trial performed by using a consecutive sample.Rehabilitation hospital affiliated with a medical school.Twenty-two male SCI patients (mean age, 46.3+/-11.9y; mean duration postinjury, 2.7y) with voiding dysfunction resulting from external urethral sphincter hypertonicity.Pudendal nerve block with 5% phenol solution under the guidance of electric stimulator.Outcomes were measured using (1) postvoid residual volume, maximal detrusor pressure, leak point pressure, bladder volume at the first uninhibited contraction, maximal bladder capacity, and urethral pressure profile; (2) rectoanal rest and squeeze pressures; and (3) quality of life measures for urination, quantified by the Quality of Life Index (QLI). Changes in bowel habit or autonomic dysreflexia were recorded.The mean decrease in postvoid residual volume was 242.8mL (mean decrease, 66%) after treatment (P<.001). The mean reduction in leak point pressure and maximal detrusor pressure were 37.1cmH(2)O and 43.3cmH(2)O, respectively (P<.05). The mean QLI significantly improved from -.74+/-.38 to.42+/-.47 (P<.001). The rectoanal pressures showed no significant difference. No complaints of fecal incontinence or other complications were noted after treatment.Pudendal nerve block performed by using 5% phenol solution was safe, easy to perform, and effective as a treatment for detrusor-sphincter dyssynergia in selected patients with SCI.

    View details for DOI 10.1053/apmr.2002.31609

    View details for Web of Science ID 000175494000019

    View details for PubMedID 11994813

  • A progressive quadratic failure criterion, part B COMPOSITES SCIENCE AND TECHNOLOGY Kuraishi, A., Tsai, S. W., Liu, K. K. 2002; 62 (12-13): 1683-1695
  • Modeling of mechanical property degradation by short-term aging at high temperatures COMPOSITES PART B-ENGINEERING Kim, J., Lee, W. I., Tsai, S. W. 2002; 33 (7): 531-543
  • Crystal structure of the macrocycle-forming thioesterase domain of the erythromycin polyketide synthase: Versatility from a unique substrate channel PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Tsai, S. C., Miercke, L. J., Krucinski, J., Gokhale, R., Chen, J. C., Foster, P. G., Cane, D. E., Khosla, C., Stroud, R. M. 2001; 98 (26): 14808-14813


    As the first structural elucidation of a modular polyketide synthase (PKS) domain, the crystal structure of the macrocycle-forming thioesterase (TE) domain from the 6-deoxyerythronolide B synthase (DEBS) was solved by a combination of multiple isomorphous replacement and multiwavelength anomalous dispersion and refined to an R factor of 24.1% to 2.8-A resolution. Its overall tertiary architecture belongs to the alpha/beta-hydrolase family, with two unusual features unprecedented in this family: a hydrophobic leucine-rich dimer interface and a substrate channel that passes through the entire protein. The active site triad, comprised of Asp-169, His-259, and Ser-142, is located in the middle of the substrate channel, suggesting the passage of the substrate through the protein. Modeling indicates that the active site can accommodate and orient the 6-deoxyerythronolide B precursor uniquely, while at the same time shielding the active site from external water and catalyzing cyclization by macrolactone formation. The geometry and organization of functional groups explain the observed substrate specificity of this TE and offer strategies for engineering macrocycle biosynthesis. Docking of a homology model of the upstream acyl carrier protein (ACP6) against the TE suggests that the 2-fold axis of the TE dimer may also be the axis of symmetry that determines the arrangement of domains in the entire DEBS. Sequence conservation suggests that all TEs from modular polyketide synthases have a similar fold, dimer 2-fold axis, and substrate channel geometry.

    View details for Web of Science ID 000172848800016

    View details for PubMedID 11752428

    View details for PubMedCentralID PMC64940

  • PECVD silicon carbide as a chemically resistant material for micromachined transducers 9th International Conference on Solid-State Sensors and Actuators Flannery, A. F., Mourlas, N. J., Storment, C. W., Tsai, S., Tan, S. H., Heck, J., Monk, D., Kim, T., Gogoi, B., Kovacs, G. T. ELSEVIER SCIENCE SA. 1998: 48–55
  • Practical considerations for the design of composite structures MECHANICS OF COMPOSITE MATERIALS AND STRUCTURES Manne, P. M., Tsai, S. W. 1998; 5 (3): 227-255
  • A progressive quadratic failure criterion for a laminate COMPOSITES SCIENCE AND TECHNOLOGY Liu, K. S., Tsai, S. W. 1998; 58 (7): 1023-1032
  • Design optimization of composite plates: Part I - Design criteria for strength, stiffness, and manufacturing complexity of composite laminates JOURNAL OF COMPOSITE MATERIALS Manne, P. M., Tsai, S. W. 1998; 32 (6): 544-571
  • Obituary: Late Professor Tsuyoshi Hayashi ADVANCED COMPOSITE MATERIALS Hoff, R., Springer, G. S., Tsai, S. W. 1998; 7 (3): 217-218
  • Design optimization of composite plates: Part II - Structural optimization by plydrop tapering JOURNAL OF COMPOSITE MATERIALS Manne, P. M., Tsai, S. W. 1998; 32 (6): 572-598
  • Manufacture and design of composite grids MATERIALES DE CONSTRUCCION Tsai, S. W., Liu, K. K., Manne, P. M. 1997; 47 (247-48): 59-71
  • Analysis and optimum design of composite grid structures JOURNAL OF COMPOSITE MATERIALS Chen, H. J., Tsai, S. W. 1996; 30 (4): 503-534
  • Analysis and behavior of grid structures COMPOSITES SCIENCE AND TECHNOLOGY Huybrechts, S., Tsai, S. W. 1996; 56 (9): 1001-1015
  • Three-dimensional effective moduli of symmetric laminates JOURNAL OF COMPOSITE MATERIALS Chen, H. J., Tsai, S. W. 1996; 30 (8): 906-917
  • SCHOOLING TAIWAN WOMEN - EDUCATIONAL-ATTAINMENT IN THE MID-20TH CENTURY Meeting of the Research-Committee-on-Social-Stratification of the International-Sociological-Association Tsai, S. L., Gates, H., Chiu, H. Y. AMER SOCIOLOGICAL ASSOC. 1994: 243–63