For loop variable error

Mass Matrix

Motor_plate = 17.010;

First_Story = 2.162;

Sec_Story = 2.162;

Top_strory = 1.790;

L_leg = 0.278;

S_Leg = 0.042;

bracket =19.75/1000;

boltnut =12.45/1000 ;

%Unbalance_mass = 0.044;

m1 = Motor_plate + 4*L_leg + 4*S_Leg + First_Story+40*bracket+64*boltnut;

m2 = 4*S_Leg+ First_Story+16*bracket+16*bracket;

m_for_k = [m1 m2];

M1 = Motor_plate + 2*S_Leg +2*L_leg ; %In kgs

M2 = First_Story+ 4*S_Leg;

M3 = Sec_Story + 4 * S_Leg;

M4 = Top_strory+2*S_Leg;

V = [M1 M2 M3 M4];

M = diag(V); % in Kgs

clear M1 M2 M3 M4 m1 m2 Motor_plate First_Story Sec_Story S_Leg;

clear Top_strory V L_leg bracket boltnut

% preallocate output variables

n_files = 2;

Time = cell(n_files, 1);

Veloc = cell(n_files, 1);

Ypk_plot = cell(n_files, 1);

Xpk_plot = cell(n_files, 1);

Y = cell(n_files, 1);

X = cell(n_files, 1);

P = cell(n_files, 1);

damp_ratio = zeros(1, n_files);

wd = zeros(1, n_files);

wn = zeros(1, n_files);

K_ex = zeros(1, n_files);

% read data from files and process each file

for i = 1:n_files

% read data from file

z1 = importdata("Xxsv0000"+num2str(i)+".txt");

% extract time and velocity data

Time{i} = z1.data(:,1);

Veloc{i} = z1.data(:,2);

% find local maxima in velocity data within the range of indices

[Ypk, Xpk] = findpeaks(Veloc{i}(1:550));

Ypk_plot{i} = Ypk(11:35);

Xpk_plot{i} = Xpk(11:35);

Y{i} = Ypk;

X{i} = Xpk;

P{i} = zeros(size(Ypk));

% plot data against time data and mark the locations of the peaks found

figure(i)

plot(Time{i}, Veloc{i}, 'DisplayName', 'data')

hold on

plot(Time{i}(Xpk_plot{i}), Ypk_plot{i}, 'dr', 'DisplayName', 'Pick points')

grid on

legend('show')

sgtitle(['File ', num2str(i)])

% calculate logarithmic decrement, damping ratio, and natural frequency

t_new = Time{i}(X{i});

y_new = Y{i};

Log_Dec = abs(log(y_new(1:end-1) ./ y_new(2:end)));

Mean_dec = mean(Log_Dec);

Damp_period = (t_new(end) - t_new(1)) / length(t_new);

wd(i) = 2*pi / Damp_period;

damp_ratio(i) = Mean_dec / sqrt(1 + Mean_dec^2);

wn(i) = wd(i) * sqrt(1 - damp_ratio(i)^2);

% calculate spring constant

K_ex(i) = m_for_k * wn(i)^2;

end

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I am facing error with K_ex(i). Am i going in right direction or making any mistake?

Kindly help me.

Answer 1

[Walter Roberson]

m_for_k = [m1 m2];

vector.

K_ex(i) = m_for_k * wn(i)^2;

vector times scalar gives vector. Vector cannot be stored in a scalar location.

[AL]

Thank you so much.