Examius
🇮🇳 GATE Biomedical Engineering · flashcards
GATE Biomedical Engineering Biomechanics Flashcards
60 question-and-answer cards covering Biomechanics as it is examined in GATE Biomedical Engineering. 24 of them are printed below, taken from across the deck — no signup, no paywall on the preview.
24 sample cards from the Biomechanics deck
Sampled from the end of the deck, so these are different cards from the ones shown on the syllabus page.
What type of mechanical material is bone (in terms of directionality)?
Bone is anisotropic (specifically orthotropic) and viscoelastic — its mechanical properties depend on the direction and rate of loading; it is stronger in compression than in tension or shear.
Rank bone's strength under compression, tension, and shear.
Bone is strongest in compression, intermediate in tension, and weakest in shear: compression $>$ tension $>$ shear.
Define a viscoelastic material.
A material exhibiting both viscous (fluid-like, time/rate-dependent) and elastic (solid-like, recoverable) behavior. Its stress–strain response depends on the rate of loading and exhibits time-dependent phenomena such as creep, stress relaxation, and hysteresis.
Define creep in a viscoelastic material.
The progressive increase in strain (deformation) over time under a constant applied stress.
Define stress relaxation in a viscoelastic material.
The gradual decrease in stress over time when a viscoelastic material is held at constant strain.
What is hysteresis in viscoelastic loading?
The phenomenon in which the loading and unloading stress–strain curves differ, forming a loop whose enclosed area represents the energy dissipated (lost as heat) per cycle.
How does loading rate affect a viscoelastic material like bone?
At higher strain rates the material behaves stiffer and stronger (higher modulus and failure stress); at lower rates it is more compliant. This rate-dependence is a hallmark of viscoelasticity.
Describe the Maxwell model of viscoelasticity.
A spring (elastic, modulus $E$) and a dashpot (viscous, viscosity $\eta$) connected in series. It represents a viscoelastic fluid: it models stress relaxation well but predicts unbounded creep.
Write the constitutive (governing) equation of the Maxwell model.
$$\frac{d\varepsilon}{dt} = \frac{1}{E}\frac{d\sigma}{dt} + \frac{\sigma}{\eta}$$ The total strain rate is the sum of the spring and dashpot strain rates.
What does the Maxwell model predict for stress relaxation at constant strain?
Stress decays exponentially: $$\sigma(t) = \sigma_0 \, e^{-t/\tau}, \quad \tau = \frac{\eta}{E}$$ where $\tau$ is the relaxation time.
Describe the Kelvin–Voigt model of viscoelasticity.
A spring (modulus $E$) and a dashpot (viscosity $\eta$) connected in parallel. It represents a viscoelastic solid: it models creep well but cannot represent instantaneous elastic deformation or stress relaxation.
Write the constitutive equation of the Kelvin–Voigt model.
$$\sigma = E\varepsilon + \eta \frac{d\varepsilon}{dt}$$ Total stress is the sum of the spring (elastic) and dashpot (viscous) stresses, which share the same strain.
What does the Kelvin–Voigt model predict for creep under constant stress $\sigma_0$?
Strain rises asymptotically toward its equilibrium value: $$\varepsilon(t) = \frac{\sigma_0}{E}\left(1 - e^{-t/\tau}\right), \quad \tau = \frac{\eta}{E}$$
Contrast the Maxwell and Kelvin–Voigt models in their elements and behaviors.
Maxwell: spring and dashpot in series; models a viscoelastic fluid; captures stress relaxation but gives unbounded (unrealistic) creep. Kelvin–Voigt: spring and dashpot in parallel; models a viscoelastic solid; captures creep and recovery but no instantaneous elasticity or stress relaxation.
Define viscosity and give its SI unit.
Viscosity $\eta$ is a fluid's resistance to shear flow, defined by $\tau = \eta \frac{du}{dy}$ (Newton's law of viscosity). SI unit is pascal-second ($\text{Pa}\cdot\text{s}$); the poise (CGS) is also used.
Why is blood a non-Newtonian fluid?
Because its apparent viscosity is not constant but decreases with increasing shear rate (shear-thinning behavior), owing to red blood cell aggregation (rouleaux) at low shear and cell deformation/alignment at high shear.
What is the Fåhraeus–Lindqvist effect?
The phenomenon in which the apparent viscosity of blood decreases as the diameter of the tube/vessel decreases (in vessels roughly $10$–$300\,\mu\text{m}$), because red cells migrate to the center, leaving a cell-free plasma layer near the wall that lubricates flow.
Define hematocrit and state its effect on blood viscosity.
Hematocrit is the volume fraction of red blood cells in blood (normally about 40–45%). Blood viscosity increases markedly (nonlinearly) with rising hematocrit.
State the Hagen–Poiseuille equation for laminar flow of blood through a cylindrical vessel.
$$Q = \frac{\pi r^{4} \Delta P}{8 \eta L}$$ where $Q$ is volumetric flow rate, $r$ the radius, $\Delta P$ the pressure drop, $\eta$ the viscosity, and $L$ the vessel length.
From Poiseuille's law, how does vascular resistance depend on vessel radius?
Resistance $R = \frac{8\eta L}{\pi r^{4}}$ varies inversely with the fourth power of the radius, so small changes in radius (vasoconstriction/dilation) produce large changes in flow and resistance.
Define the Reynolds number and its significance for blood flow.
$$Re = \frac{\rho v D}{\eta}$$ a dimensionless ratio of inertial to viscous forces. Low $Re$ indicates laminar flow; flow becomes turbulent above a critical value (about 2000–2300 in tubes), which can occur at heart valves or stenoses.
What is wall shear stress on a blood vessel and why is it physiologically important?
The tangential frictional force per unit area exerted by flowing blood on the endothelium; for Poiseuille flow $\tau_w = \frac{4\eta Q}{\pi r^{3}}$. It regulates endothelial function, vasodilation (nitric oxide release), and is implicated in atherosclerosis where shear is low/oscillatory.
State the law of Laplace for a thin-walled cylindrical vessel.
$$T = P \cdot r$$ wall tension equals transmural pressure times radius (for a cylinder; wall stress $\sigma = \frac{P r}{t}$ for wall thickness $t$). It explains why large-radius/thin vessels are prone to rupture (e.g., aneurysms).
What is plug flow (blunted velocity profile) of blood in small vessels?
In narrow vessels, red cells concentrate in the central core moving as a 'plug', flattening the otherwise parabolic velocity profile, due to axial migration of cells and the cell-free plasma layer at the wall.
What this deck covers
The Biomechanics deck follows the GATE Biomedical Engineering Biomechanics syllabus — 4 chapters and 12 topics — so questions land on material that is genuinely examinable rather than trivia around it. That works out to roughly 15.0 cards per chapter.
Answers are written to be recallable, not just readable — averaging about 192 characters, which is long enough to carry the reasoning and short enough to say out loud.
A deck like this earns its keep on the second and third pass. Read the syllabus first so you know the shape of the subject, then use the cards to find the specific facts that have not stuck.
Biomechanics flashcards FAQ
How many Biomechanics flashcards are in this GATE Biomedical Engineering deck?
60 cards. This page previews 24 of them, sampled evenly across the deck so you can judge the difficulty before installing anything.
Are these GATE Biomedical Engineering flashcards free?
Yes. The preview here is free to read with no signup, and the full 60-card deck is free inside the Examius app.
What do the Biomechanics cards cover?
They follow the GATE Biomedical Engineering Biomechanics syllabus — 4 chapters and 12 topics — so the questions track what is actually examinable.
How should I use these flashcards?
Read the syllabus first so you know the shape of the subject, then drill the deck. Examius schedules each card with spaced repetition, so cards you keep missing come back sooner and ones you know drift further apart.