For the ship building industry, ship accidents continue to occur regardless of efforts to prevent them. Some extreme or accidental situations such as collision and grounding need to be considered at the design stage. The rigid body dynamic program MCOL was developed in LS-DYNA and used in simulation of ship collisions analysis. The MCOL solver requires an input file as .mco file containing the hydrodynamic parameters such as the rigid body added mass matrix, hydrostatic restoring matrix, buoyancy parameters, and wave damping matrices for the body, etc. These parameters were provided by third-party software previously. In this paper, the new development on LS-DYNA/MCOL-Aqwa coupling analysis has been implemented in which the Aqwa solver can automatically create the MCOL required hydrodynamic database, .mco file.
LS-DYNA has been used in automotive industries for many years, especially in vehicle crashworthi-ness and occupant safety analysis areas. Besides that, LS-DYNA also provides many useful features for NVH (Noise, Vibration and Harshness) analysis. During the past few years, based on the feedback and suggestions from users, many updates and enhancements in the NVH solvers have been imple-mented, including - Fast FRF analysis with reduced eigenvectors. - Frequency dependent adaptive remeshing for BEM acoustics. - Frequency interpolation for BEM acoustic solvers. - Fluid added mass computation and its application in modal and vibration analysis. - Coupling of acoustic spectral element method and piezoelectric materials for ultrasonic sensor simulation. - Enhanced d3max output. - New options in fatigue solvers. - Other enhancements.
The standard eigenvalue problem for Implicit Mechanics in LS-DYNA is ΚΦ = ΜΦΛ , where Κ and Μ , the stiffness and mass matrices, are real and symmetric positive semi-definite in most applications. LS-DYNA offers three main algorithms for this problem, chosen with EIGMTH (field 7 of line 1 of *CONTROL_IMPLICIT_EIGENVALUE). The three algorithms currently available are • Lanczos (EIGMTH=2); • LOGPCG (EIGMTH=102); • Fast Lanczos (EIGMTH=103). This paper will give an overview of these methods, guidelines on when each should be used, performance comparisons, and recent enhancements. For non-symmetric problems, LS-DYNA also has an SMP solver, which relies on ARPACK [1,2]. An MPP solver relying on a different algorithm is being actively developed and is briefly mentioned in the last section.
Introduction of LS-DYNA® MCOL solver coupling with Ansys Aqwa for the application in shipbuilding analysis