Economic Life Determination for a Military Aircraft

Cyclic-fatigue crack growth in composite and adhesively-bonded structures: The FAA slow crack growth approach to certification and the problem of similitude

“…One of the key lessons learnt when assessing the growth of cracks in (metallic) operational aircraft is the need to use a da/dN versus ΔK curve that differs from that obtained using tests described in the main body of the ASTM fatigue crack-growth standard E647-13a [32,[45][46][47][48] This is due to the fatigue crack-growth being dependent of the length of the initial crack, see Appendix X3 in [45]. Indeed, as explained in [45] using a da/dN versus ΔK curve that has been determined using tests described in the main body of the ASTM standard can lead to very non-conservative (i.e.…”

Tools and methods for addressing the durability of rolling stock

“…However, it is well known, see ASTM E647, that the fatigue threshold reduces as the crack length reduces. Experimental data that illustrates this are given in [36,37]. B + and L6B2 are commonly used steels in rollingstock.…”

Experimental Detection and Quantitative Interrogation of Damage in a Jointed Composite Structure

“…Supplemental benefits of a SHM system include the cost savings due to maintenance which becomes significant over the serviceable lifetime of an aerospace structure. In a study conducted by the U.S. Air Force, an average of $1.4 million is spent on a single comprehensive F-15E maintenance event [4]. The FAA enforces four specific inspection checks on commercial transport aircraft before the aircraft is considered flightworthy [5].…”

“…%DI.m %calculate the damage index from sensing information over range %of excitation frequencies clc close all clear all %%% 20kHz %%%%% % Sensor 2 num=xlsread('C1B020kHzS2_torque0p'); nx=length(num); ns=88; aa1=num(ns:nx,:); num=xlsread('C1B020kHzS2_torque25p'); aal1_1=num(ns:nx,:); num=xlsread('C1B020kHzS2_torque50p'); aal1_2=num(ns:nx,:); num=xlsread('C1B020kHzS2_torque75p'); aal1_3=num(ns:nx,:); num=xlsread('C1B020kHzS2_torque100p'); aal1_4=num(ns:nx,:); % Sensor 3 num=xlsread('C1B020kHzS3_torque0p'); aa2=num(ns:nx,:); num=xlsread('C1B020kHzS3_torque25p'); aal2_1=num(ns:nx,:); num=xlsread('C1B020kHzS3_torque50p'); aal2_2=num(ns:nx,:); num=xlsread('C1B020kHzS3_torque75p'); aal2_3=num(ns:nx,:); num=xlsread('C1B020kHzS3_torque100p'); aal2_4=num(ns:nx,:); % Sensor 4 num=xlsread('C1B020kHzS4_torque0p'); aa1h=num(ns:nx,:); num=xlsread('C1B020kHzS4_torque25p'); aal1h_1=num(ns:nx,:); num=xlsread('C1B020kHzS4_torque50p'); aal1h_2=num(ns:nx,:); num=xlsread('C1B020kHzS4_torque75p'); aal1h_3=num(ns:nx,:); num=xlsread('C1B020kHzS4_torque100p'); aal1h_4=num(ns:nx,:); fsp=0; fpp=80; spt=.1; %frequency increment in kHz ik=(40-fsp)/spt+1; %%%%% 40kHz %%%%% % % % Sensor 2 num=xlsread('C1B040kHzS2_torque0p'); nx=length(num); ns=88; aa1=num(ns:nx,:); num=xlsread('C1B040kHzS2_torque25p'); aal1_1=num(ns:nx,:); num=xlsread('C1B040kHzS2_torque50p'); aal1_2=num(ns:nx,:); num=xlsread('C1B040kHzS2_torque75p'); aal1_3=num(ns:nx,:); num=xlsread('C1B040kHzS2_torque100p'); aal1_4=num(ns:nx,:); % % % Sensor 3 num=xlsread('C1B040kHzS3_torque0p'); aa2=num(ns:nx,:); aal2_1=num(ns:nx,:); num=xlsread('C1B040kHzS3_torque50p'); aal2_2=num(ns:nx,:); num=xlsread('C1B040kHzS3_torque75p'); aal2_3=num(ns:nx,:); num=xlsread('C1B040kHzS3_torque100p'); aal2_4=num(ns:nx,:); % % % Sensor 4 num=xlsread('C1B040kHzS4_torque0p'); aa1h=num(ns:nx,:); num=xlsread('C1B040kHzS4_torque25p'); aal1h_1=num(ns:nx,:); num=xlsread('C1B040kHzS4_torque50p'); aal1h_2=num(ns:nx,:); num=xlsread('C1B040kHzS4_torque75p'); aal1h_3=num(ns:nx,:); num=xlsread('C1B040kHzS4_torque100p'); aal1h_4=num(ns:nx,:); % fsp=0; fpp=80; spt=.1; %frequency increment in kHz ik=(40-fsp)/spt+1; % %%%%% 60kHz %%%%% % Sensor 2 num=xlsread('C1B060kHzS2_torque0p'); nx=length(num); ns=88; aa1=num(ns:nx,:); num=xlsread('C1B060kHzS2_torque25p'); aal1_1=num(ns:nx,:); num=xlsread('C1B060kHzS2_torque50p'); aal1_2=num(ns:nx,:); num=xlsread('C1B060kHzS2_torque75p'); aal1_3=num(ns:nx,:); num=xlsread('C1B060kHzS2_torque100p'); aal1_4=num(ns:nx,:); % Sensor 3 num=xlsread('C1B060kHzS3_torque0p'); aa2=num(ns:nx,:); num=xlsread('C1B060kHzS3_torque25p'); aal2_1=num(ns:nx,:); num=xlsread('C1B060kHzS3_torque50p'); aal2_2=num(ns:nx,:); num=xlsread('C1B060kHzS3_torque75p'); aal2_3=num(ns:nx,:); num=xlsread('C1B060kHzS3_torque100p'); aal2_4=num(ns:nx,:); % Sensor 4 num=xlsread('C1B060kHzS4_torque0p'); aa1h=num(ns:nx,:); num=xlsread('C1B060kHzS4_torque25p'); aal1h_1=num(ns:nx,:); num=xlsread('C1B060kHzS4_torque50p'); aal1h_2=num(ns:nx,:); num=xlsread('C1B060kHzS4_torque75p'); aal1h_3=num(ns:nx,:); num=xlsread('C1B060kHzS4_torque100p'); aal1h_4=num(ns:nx,:); fsp=20; fpp=100; spt=.1; %frequency increment in kHz ik=(60-fsp)/spt+1; %%%%%% 80kHz %%%%% % % Sensor 2 num=xlsread('C1B080kHzS2_torque0p'); nx=length(num); ns=88; aa1=num(ns:nx,:); num=xlsread('C1B080kHzS2_torque25p'); aal1_1=num(ns:nx,:); num=xlsread('C1B080kHzS2_torque50p'); aal1_2=num(ns:nx,:); num=xlsread('C1B080kHzS2_torque75p'); aal1_3=num(ns:nx,:); num=xlsread('C1B080kHzS2_torque100p'); aal1_4=num(ns:nx,:); (4,1); sum(1,1) = DI_array(3,1) + DI_array(4,1); sum(2,1) = DI_array(3,2) + DI_array(4,2); sum(3,1) = DI_array(1,3) + DI_array (2,3); sum(4,1) = DI_array(1,4) + DI_array(2,4); % % sort sensor sums in ascending order, in separate column vector asc_sum = zeros(4,2); asc_...…”

“…Since the damage index as a key feature relies entirely on the sensing response, any change may affect the overall damage index, and thus the discrimination capabilities of the diagnostic system. % Sensor 3 num=xlsread('C1B080kHzS3_torque0p'); aa2=num(ns:nx,:); num=xlsread('C1B080kHzS3_torque25p'); aal2_1=num(ns:nx,:); num=xlsread('C1B080kHzS3_torque50p'); aal2_2=num(ns:nx,:); num=xlsread('C1B080kHzS3_torque75p'); aal2_3=num(ns:nx,:); num=xlsread('C1B080kHzS3_torque100p'); aal2_4=num(ns:nx,:); % Sensor 4 num=xlsread('C1B080kHzS4_torque0p'); aa1h=num(ns:nx,:); num=xlsread('C1B080kHzS4_torque25p'); aal1h_1=num(ns:nx,:); num=xlsread('C1B080kHzS4_torque50p'); aal1h_2=num(ns:nx,:); num=xlsread('C1B080kHzS4_torque75p'); aal1h_3=num(ns:nx,:); num=xlsread('C1B080kHzS4_torque100p'); aal1h_4=num(ns:nx,:); fsp=40; fpp=120; spt=.1; %frequency increment in kHz ik=(80-fsp)/spt+1; %%%%% 100kHz %%%%% % % Sensor 2 num=xlsread('C1B0100kHzS2_torque0p'); nx=length(num); ns=88; aa1=num(ns:nx,:); num=xlsread('C1B0100kHzS2_torque25p'); aal1_1=num(ns:nx,:); num=xlsread('C1B0100kHzS2_torque50p'); aal1_2=num(ns:nx,:); num=xlsread('C1B0100kHzS2_torque75p'); aal1_3=num(ns:nx,:); num=xlsread('C1B0100kHzS2_torque100p'); aal1_4=num(ns:nx,:); % Sensor 3 num=xlsread('C1B0100kHzS3_torque0p'); aa2=num(ns:nx,:); num=xlsread('C1B0100kHzS3_torque25p'); aal2_1=num(ns:nx,:); num=xlsread('C1B0100kHzS3_torque50p'); aal2_2=num(ns:nx,:); num=xlsread('C1B0100kHzS3_torque75p'); aal2_3=num(ns:nx,:); num=xlsread('C1B0100kHzS3_torque100p'); aal2_4=num(ns:nx,:); % Sensor 4 num=xlsread('C1B0100kHzS4_torque0p'); aa1h=num(ns:nx,:); num=xlsread('C1B0100kHzS4_torque25p'); aal1h_1=num(ns:nx,:); num=xlsread('C1B0100kHzS4_torque50p'); aal1h_2=num(ns:nx,:); num=xlsread('C1B0100kHzS4_torque75p'); aal1h_3=num(ns:nx,:); num=xlsread('C1B0100kHzS4_torque100p'); aal1h_4=num(ns:nx,:); fsp=60; fpp=140; spt=.1; %frequency increment in kHz ik=(100-fsp)/spt+1; %%%% 120kHz %%%%% % % Sensor 2 num=xlsread('C1B0120kHzS2_torque0p'); nx=length(num); ns=88; aa1=num(ns:nx,:); num=xlsread('C1B0120kHzS2_torque25p'); aal1_1=num(ns:nx,:); num=xlsread('C1B0120kHzS2_torque50p'); aal1_2=num(ns:nx,:); (h,'MarkerSize',15,'LineWidth',4) xlabel('Torque loss (%)') ylabel('Frequency (kHz)') zlabel('Damage Index') elseif sum(2,1) == asc_sum (4,2) asc_sum(4,1) = 2; end if sum(3,1) == asc_sum (1,2) asc_sum(1,1) = 3; elseif sum(3,1) == asc_sum (2,2) asc_sum(2,1) = 3; elseif sum(3,1) == asc_sum (3,2) asc_sum(3,1) = 3; elseif sum(3,1) == asc_sum (4,2) asc_sum(4,1) = 3; end if sum(4,1) == asc_sum (1,2) asc_sum(1,1) = 4; elseif sum(4,1) == asc_sum (2,2) asc_sum(2,1) = 4; elseif sum(4,1) == asc_sum …”