Co-ordination & Harmonisation of Advanced e-Infrastructures for Research and Education Data Sharing Research Infrastructures Grant Agreement n Designing Better Roads with GAMES (General Analysis for Multi-layered Elastic Systems) James Maina, CSIR Africa-Arabia (South) All-Hands Meeting Pretoria, 03/2013

Co-ordination & Harmonisation of Advanced e-Infrastructures for Research and Education Data Sharing Research Infrastructures Grant Agreement n

Co-ordination & Harmonisation of Advanced e-Infrastructures for Research and Education Data Sharing Research Infrastructures Grant Agreement n

4 Date Author | address | AA ROC AllHands | Pretoria 03/2013  To develop improved tools for mechanistic road pavement analysis and evaluation. Derived closed form solutions of pavement responses. Improved understanding of road structural behaviour under the actions of multiple loads (tyres). Research objectives and motivation

5 Date Author | address | AA ROC AllHands | Pretoria 03/2013 Road damage...

6 Date Author | address | AA ROC AllHands | Pretoria 03/2013 Road pavement model... P/σ Surfacing: h 1, E 1, v 1 Selected Layer: h 4, E 4, v 4 Base Layer: h 2, E 2, v 2 Subgrade/ Foundation: h 5, E 5, v 5 Subbase Layer: h 3, E 3, v 3 APPLIED LOAD/STRESSES P/σ Pavement Response: Stresses & Strains Stress Rotation Vertical, Longitudinal & Lateral 3D Contact Stresses Side view of tyre End view of tyre

7 Date Author | address | AA ROC AllHands | Pretoria 03/2013 Governing Equations... are Lame Constants

8 Date Author | address | AA ROC AllHands | Pretoria 03/2013 Equilibrium Equations... are Lame Constants

9 Date Author | address | AA ROC AllHands | Pretoria 03/2013 Hankel Transform of Equilbrium Eqs... where

10 Date Author | address | AA ROC AllHands | Pretoria 03/2013 Hankel Inverse Transform to obtain pavement responses...

11 Date Author | address | AA ROC AllHands | Pretoria 03/2013 Pavement: Multilayered elastic system with a possibility of interface slip. Surface load: Single/Multiple circular loads. Analysis: Single/Multiple points of interest. Response: Stresses, strains, and displacements General features & assumptions

12 Date Author | address | AA ROC AllHands | Pretoria 03/2013 GAMES is written in Fortran90 GAMES can be parallelized (OpenMP, MPICH) by individually obtaining solutions on individual x,y,z points from individual loads then combining these solutions using principle of superposition; thus utilizing CPUs in parallel; and achieving speed-up. Computational Aspects

13 Date Author | address | AA ROC AllHands | Pretoria 03/2013  GAMES is an established road pavement engineering code  Large problem sizes demand long computational runs in single processor environment 20,000 x,y,z points = 1 week 500,000 x,y,z points = 20 weeks  Large problems thus not practical in single processor environment Computational Bottlenecks

14 Date Author | address | AA ROC AllHands | Pretoria 03/2013 Prospects for the future (use of actual measured tyre loads)

15 Date Author | address | AA ROC AllHands | Pretoria 03/2013 Prospects for the future (Eight (8) Axle Truck – Vertical Contact Stress - Foot Prints measured from previous slide….)

16 Date Author | address | AA ROC AllHands | Pretoria 03/2013 Prospects for the future (Tyre contact pressure distribution represented by 206 points….)

17 Date Author | address | AA ROC AllHands | Pretoria 03/2013 Prospects for the future (Some of the results – indicating areas within pavement structure with higher potential for failure – under the front axle)

18 Date Author | address | AA ROC AllHands | Pretoria 03/2013 Prospects for the future (Some of the results – indicating areas within pavement structure with higher potential for failure – under the front axle)

19 Date Author | address | AA ROC AllHands | Pretoria 03/2013 Prospects for the future (Failure starts from the surface – z=0 conventional wisdom – always failure starts from bottom of the top layer!) (Nishizawa and Matsuno - Japan)

20 Date Author | address | AA ROC AllHands | Pretoria 03/2013 Outlook  GAMES can be used to solve much larger pavement engineering problems than before  Further optimization of GAMES parallelization may yield another doubling in speed-up through  Road designers and owners to benefit from the use of cloud computing  We wish to run problems with 30 tyres (each tyre represented by ~200 multiple loads) on 1mm x 1mm x 1mm 3D grid. Total analysis number will > 200x30x500,000 (each involving Hankel Transform and Hankel Inverse Transforms) or more!