Pengantar Biomekanika. Dita Ayu Mayasari, ST., M.Biotech Biomedical Engineering Univ. Dian Nuswantoro

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Stanley Neil Small
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1 Pengantar Biomekanika Dita Ayu Mayasari, ST., M.Biotech Biomedical Engineering Univ. Dian Nuswantoro

2 Dasar-Dasar Biomekanika

3 What is Biomechanics? Applies mechanical principles to the human body in order to understand the mechanical influences on bone and joint health (Kelleys and Firestein s Textbook of Rheumatology 10 th Ed, 2017)

4 Why should we learn about biomechanics? Ergonomic Utility Sports Biomechanics Medical Rehabilitation Forensic

5 Why should we learn about biomechanics?

7 Elements of Biomechanics Statics: Studying systems that are in equilibrium, either at rest or moving at a constant velocity. Dynamics: Studying systems that are in motion with acceleration and deceleration. Kinetics: Studying what causes motion, the forces and moments at work. Kinematics: Describing the effect of forces on a system, motion patterns including linear and angular changes in velocity over time. Position, displacement, velocity, and acceleration are studied.

Biomechanical Principles Basic biomechanics relies heavily on Newtonian mechanics Newton s First Law Law of Inertia Objects tend to resist changes in their state of motion.

8 Biomechanical Principles Basic biomechanics relies heavily on Newtonian mechanics Newton s First Law Law of Inertia Objects tend to resist changes in their state of motion. Newton s Second Law Law of Acceleration Links the kinematics of a body to its kinetics Newton s Third law Law of Reaction There is an equal and opposite reaction force for every action (force)

9 Force Gravitation Normal F g = GM R 2 m FN Spring Friction F s = kx F f = F c

10 Vector Has magnitude and direction Vectors are similarly represented in three dimensions in terms of their i, j, and k components A set of forces may be combined into an equivalent force denoted the resultant R Vector multiplication consists of two distinct operations: the dot and cross products A B = AB cos A x B = AB sin

11 Penjumlahan & Pengurangan Vektor

12 Torque Forces describe changes in linear motion which means changes in velocities, while torques describe how these same forces can change angular motion which means changes in angular velocities τ = r F

13 Momen Inersia ukuran kelembaman suatu benda untuk berotasi terhadap porosnya analog rotasi daripada massa berperan dalam dinamika rotasi seperti massa dalam dinamika dasar, dan menentukan hubungan antara momentum sudut dan kecepatan sudut, momen gaya dan percepatan sudut, dan beberapa besaran lain I = m r 2 dm

14 Static Equilibrium F = 0 M = 0

15 Contoh Masalah : Diketahui: Seseorang dengan berat 160 lb menahan beban bola 10 lb dengan siku menekuk 90 derajat Hitung: Gaya yang harus dihasilkan oleh otot bisep (Fb) Jawab:

16 Biotransportasi Mekanika Fluida Zat Alir cairan, gas Fluida statis & dinamis

17 Hidrostatika TEKANAN HIDROSTATIKA df P = df da p o P m = P 0 + ρgh h m

18 Tekanan terukur P = P 0 + ρgh P P 0 = ρgh misal h = 80 mm, berarti tekanan gas dlm tabung 80 mmhg

19 Hukum Archimedes Sebuah benda bila berada dalam zat cair akan mendapat gaya ke atas (B) sebesar berat zat cair yang dipindahkan F 2 F 1 = B = ρ zat cair g v benda F 1 F 2

20 Hidrodinamika Laminer : memiliki garis arus sendiri-sendiri kerapatan dan kompresibilitas sama Turbulen : garis arusnya saling berpotongan dan kerapatannya tidak merata

21 Bilangan Reynold V = kecepatan aliran D = diameter pipa η = koefisien viskositas bila R < 2000 aliran laminer R > 3000 aliran turbulen R = ρvd η

22 Persamaan kontinuitas volume zat cair yang mengalir perdetik di setiap titik adalah sama Q 1 = Q 2 = Q 3 A 1 V 1 = A 2 V 2 = A 3 V 3 A : luas penampang pipa V : kecepatan aliran

23 Persamaan Bernuolli

24 Latihan Soal 1. Seorang anak (ρ=0,98 g/cm 2 ) berada dalam keadaan terapung dengan sebagian tubuhnya berada dalam kolam. Berapa bagian tubuh yang berada di dalam air? 2. Sebuah bola ditengahnyan berongga, r dalam =10 cm dan r rongga =8cm. Bila berada dalam keadaan melayang dalam air maka tentukan massa jenis bola tersebut.

25 Diketahui: Seseorang dengan berat 150 lb (berat kaki dari berat total tubuh) W? Hitung:

DCC5143: FLUID MECHANICS

DCC5143: FLUID MECHANICS SECTION A: 50 MARKS BAHAGIAN A: 50 MARKAH INSTRUCTION: This section consists of TWO (2) structured questions. Please answer ALL questions. ARAHAN: Bahagian ini mengandungi DUA (2) soalan berstruktur. Sila