scholarly journals Stress and strain analysis from dynamic loads of mechanical hand using finite element method

Author(s):  
Iskandar Hasanuddin ◽  
Husaini ◽  
M. Syahril Anwar ◽  
B.Z. Sandy Yudha ◽  
Hasan Akhyar
2019 ◽  
Vol 31 (1) ◽  
pp. 47-54
Author(s):  
Abdul Kadir ◽  
Soegeng Hardjono

Analysis of the Strength of Floating Dock Structures for Pioneer Ports: Geographically, Indonesia's position is very strategic towards trade traffic because it is located between two continents and two oceans. This condition needs to be supported by inter-island transportation facilities and infrastructure including adequate ports. Port planning needs to be adapted to Indonesia's natural conditions which are in the area of the most active tectonic plate fire ring and contribute greatly to the occurrence of earthquakes on earth. One alternative port designs that can be developed is floating docks that are designed and planned to be able to withstand internal loads from the cargo and external loads from the environment in the form of water fills, waves and ship collision forces when anchored. The structure of the floating dock has a dynamic nature where the structure of the pier will be part of the load buoyancy. Thus, the greater the weight of the structure, the smaller the capacity of the dock will be. This paper provides an example of the strength analysis of the structure of the pioneer floating dock using Finite Element Method for stress and strain analysis due to the lateral and vertical loads that occur. The results obtained from the analysis carried out identify that the stress and strain values were still below the allowable critical value which mean that they were still safe.Keywords: Floating dock, loading, strength structure. Secara geografis, posisi Indonesia sangat strategis terhadap lalu lintas perdagangan karena terletak antara dua benua dan dua samudra. Kondisi tersebut perlu didukung oleh sarana dan prasarana transportasi antar pulau termasuk pelabuhan yang memadai. Perencanaan pelabuhan perlu disesuaikan dengan kondisi alam Indonesia yang berada pada daerah rangkaian cincin api lempeng tektonik paling aktif dan berkontribusi besar terhadap terjadinya gempa bumi. Salah satu alternatif desain pelabuhan yang bisa dikembangkan adalah dermaga apung yang didesain dan direncanakan untuk menahan beban baik beban internal akibat muatan maupun beban eksternal dari lingkungan yang berupa tumpuan air, hempasan gelombang, maupun gaya tumbukan kapal saat sandar. Struktur dermaga apung memilki sifat yang dinamis dimana struktur dermaga akan menjadi bagian dari beban daya apung dermaga, sehingga semakin besar berat struktur maka akan semakin kecil kapasitas dermaga. Tulisan ini memberikan contoh analisis kekuatan struktur dermaga apung perintis yang menggunakan Finite Element Method untuk analisa tegangan dan regangan akibat beban lateral dan vertikal yang terjadi. Hasil yang diperoleh dari analisa yang dilakukan  yakni bahwa nilai tegangan dan regangan yang didapatkan masih dibawah nilai kritis yang diizinkan sehingga masih dalam kondisi aman.Kata kunci : dermaga terapung, pembebanan, kekuatan struktur.


1993 ◽  
Vol 115 (4B) ◽  
pp. 497-502 ◽  
Author(s):  
Lewis K. Waldman ◽  
Andrew D. McCulloch

Nonhomogeneous distributions of strains are simulated and utilized to determine two potential errors in the measurement of cardiac strains. First, the error associated with the use of single-plane imaging of myocardial markers is examined. We found that this error ranges from small to large values depending on the assumed variation in stretch. If variations in stretch are not accompanied by substantial regional changes in ventricular radius, the associated error tends to be quite small. However, if the nonuniform stretch field is a result of substantial variations in local curvature from their reference values, large errors in stretch and strain occur. For canine hearts with circumferential radii of 2 to 4 cm, these errors in stretch may be as great as 30 percent or more. Moreover, gradients in stretch may be over- or underestimated by as much as 100 percent. In the second part of this analysis, the influence of random measurement errors in the coordinate positions of markers on strains computed from them is studied. Arrays of markers covering about 16 cm2 of ventricular epicardium are assumed and nonuniform stretches imposed. The reference and deformed positions of the markers are perturbed with Gaussian noise with a standard deviation of 0.1 mm, and then strains are computed using either homogeneous strain theory or a nonhomogeneous finite element method. For the strain distributions prescribed, it is found that the finite element method reduces the error resulting from noise by about 50 percent over most of the region. Accurate measurements of cardiac strain distributions are needed for correlation with and validation of realistic three-dimensional stress analyses of the heart. Moreover, with the advent of increasingly effective noninvasive methods to measure cardiac deformation such as magnetic resonance imaging, the use of nonhomogeneous strain analysis to determine more accurate strain distributions has increasing clinical significance.


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