Simulasi Komputer Distribusi Tegangan pada Helm Sepeda Motor dari Bahan Komposit GFRP BTQN 157 EX Dilapisi Busa (Foam) terhadap Beban Impak Kecepatan Tinggi Menggunakan MSC/Nastran 4.5

Abstract

This study focuses on a verification using simulation of stress distribution of helmet motorcycle with high speed impact. The helmet is made of Glass Fiber Reinforced Plastics (GFRP). Two types of helmet model were used in this study, they are of composite helmet and foam-coated composite helmet. The helmets with load of 8.2MPa were impacted from several impact locations such as from the top, the side and the back of the helmets. To observe the stress distribution on the helmets, computer simulation using AutoCad2002 and MSC/Nastran 4.5 was used. The simulation showed that impacted from back direction (X-axis) measured at Y-direction was -4.7MPa of stress was developed at time 0.0039μs and Z-direction was -3.4MPa of stress was developed at time 0.0040μs. For the composite helmet the condition stress propagated into the helmet became decreasingly smaller at the distance 66mm from impact direction. For the composite helmet foam-coated that impacted from top direction (Z-axis) by X direction was -3MPa of was developed at the time 0.0042μs and Y direction was 2.6MPa of stress was developed at time 0.0045μs. From the result of both helmet experiments it was showed that foam-coated composite helmet were able to absorb stress impact up to 1.6%.

Dalam penelitian ini dilakukan simulasi distribusi tegangan pada helm sepeda motor yang dikenai beban impak kecepatan tinggi. Helm dibuat dari bahan komposit Glass Fiber Reinforced Plastics (GFRP). Konstruksi helm dibuat dua jenis yaitu helm komposit dan helm komposit dilapisi busa. Helm dibebani dengan beban impak pada tiga posisi yaitu pada bagian atas, samping, dan belakang dengan beban impak sebesar 8,2 MPa. Untuk melihat besarnya distribusi tegangan pada kedua helm ini, dilakukan simulasi dengan menggunakan perangkat lunak AutoCad 2002 dan MSC/Nastran 4.5. Hasil simulasi menunjukkan bahwa pada helm komposit tegangan yang paling besar terjadi pada pemberian beban impak belakang arah X dipeoleh pada titik Y sebesar -4,7 Mpa saat t 0.0039μs dan titik Z sebesar -3,4 MPa saat t = 0,0040 μs. Penjalaran tegangan pada jarak 66mm dari titik pembebanan tampak semakin mengecil. Pada helm komposit dilapisi busa tegangan yang paling besar terjadi pada pemberian beban impak atas arah Z diperoleh pada titik X sebesar -3,0 MPa saat t 0,0042μs dan titik Y sebesar -2,6 MPa, saat t =0,0045 μs. Hasil simulasi memberi informasi bahwa helm komposit dilapisi busa mampu menyerap tegangan hingga 1,6%.