In structures or machine components, fatigue failure is very common. It is initiated by a small defect which leads it to a catastrophic failure. The material defects, inclusion, impurities and machine operation can always be vulnerable to crack initiation and hence fatigue cannot be avoided. In metallic structures, the thermal loads can also alter the material properties such as young’s modulus, tangent modulus, yield stress, and ultimate tensile strength, etc. Consequently, in the presence of increasing temperature, it can be inferred that the material might become soft near the vicinity of the crack tip, which can lead to increase the size of the plastic zone under the same mechanical loads. Therefore, it is very complicated to estimate the retardation or acceleration of fatigue crack propagation under thermo-mechanical loads. This research investigates the interdependencies of crack depth and crack location on the dynamic response of a non-prismatic cantilever beam under thermo-mechanical loads. Temperature can influence the stiffness of the structure, thus, the change in stiffness can lead to variation in frequency, damping and amplitude response. These variations are used as key parameters to quantify damage of Aluminum 2024 specimen under thermo-mechanical loads. Experiments are performed on non-prismatic cantilever beams at non-heating (room temperature) and elevated temperature, i.e., 50°C, 100°C, 150°C and 200°C. This study considers a non-prismatic cantilever beam having various initially seeded crack depth (0.5 mm to 2.5 mm) and crack of 0.5 mm with natural propagation under load located at various locations, i.e., 5%, 10% and 15% of the total length from fixed end, respectively. The analytical, numerical and experimental results for all configurations are found in good agreement. Using available experimental data, a novel tool is formulated for in-situ damage assessment in the metallic structures for the first time under thermo-mechanical loads. This tool can quantify and locate damage using the dynamic response and temperature including the diagnosis of subsurface cracking. It fits around 82% of available data for validation within 10% of prediction error against a small change in the response parameter. The obtained results demonstrate the possibility to diagnose the crack growth at any instant within the operational condition under thermo-mechanical loads.
کوئی ملتا ہی نہیں سوختہ پا میری طرح جس کو معلوم ہو وحشت کا پتا میری طرح میرے جیون کو اُداسی سے ملانے والا! دشت میں پھِرتا رہے آبلہ پا میری طرح میں نے احباب کو آواز لگا کر پوچھا کوئی رہتا ہے شبِ غم میں سدا، میری طرح؟ اے کئی دن سے مرے ذہن پہ چھائے ہوئے شخص تو مجھے وصل کے سپنے نہ دکھا میری طرح رات بھر چاند کو احوال سنانے کے لیے کیا ٹھہرتی ہے دریچوں میں ہوا، میری طرح؟ زندگی! میری طرف دیکھ کے ایماں سے بتا ایک بھی شخص کوئی تجھ کو مِلا، میری طرح تند اور تیز ہواؤں کے علاقے میں سعید زیست کرتا ہے فقط دل کا دِیا میری طرح
Almighty Allah bestowed honors and respect to mankind. Keeping in view the honor of mankind, Allah SWT blessed them also a purified, cleanse and Halal [permissible & Lawful] food. Moreover, the religious teachings are very clear and transparent in this regard to highlight the difference between what is beneficial and useful for them and what is harmful and injurious. Almighty Allah is very kind and compassionate to his servants and described definite commands and orders about such Animals which are adequate and effective to mankind and counts them in Halal category and otherwise are considered Restricted and Haram [impressible & unlawful]. So all kinds of animals which are harmful are prohibited with exception of their some body organs and which are useful are described with their all qualities are halal in mentioned divine religions i.e. Judaism, Christianity and Islam coupled with little changes in rulings about the use of body organs of impermissible animals like use of bones or skin etc. The paper emphasis on describing the disparities of three divine religions regarding the use of organs, skin of animals, bones and highlight their procedures of making them safe and useable for mankind. This study will lead us to know that which divine religion is more applicable and provides cleanse food to their followers along with having the status of eternity strength among three.
Modeling of high strength and wear resistance aluminum alloy based casting of composite material developed via conventional foundry method which is one of the most economical versatile and active research area and so for has not been thoroughly investigated. Due to complex nature of the composite materials and their related problems such as the nonlinear relationship between composition, processing parameters, heat treatment with the strength and abrasive wear, resistance can more efficiently be modeled by artificial neural networks. The artificial neural networks modeling requires sufficient data concerned with chemical composition , processing parameters and the resulting mechanical properties which were not available for such type of modeling. Therefore, a wide range of experimental work was conducted for the development of aluminum composites using conventional foundry method. Alloy containing Cu-Mg- Zn as matrix and reinforced with 1- 15 % Al 2 O 3 particles were prepared using stir casting method. The molten alloys composites were cast in metal mold. More than eighty standard samples were prepared for tensile tests and sixty samples were given solution treatment at 580 0 C for 1⁄2 hour and tempered at 120 0 C for 24 hours. Various characterization techniques apparatus such as X-ray Spectrometer, Scanning Electron Microscope, Optical Metallurgical Microscope, Universal Tensile Testing Machine, Vickers Hardness and Abrasive Wear Testing Machine were used to investigate the chemical composition, microstructural features, density, tensile strength, ductility (elongation), hardness and abrasive wear resistance. xixThese investigations including the material development and characterization were used for data generations as needed for modeling of high strength and abrasive wear résistance aluminum cast composites. For modeling purpose a multilayer perceptron (MLP) feedforward was developed and back propagation learning algorithm was used for training, testing and validation of the model. The modeling results shows that an architecture of 14 inputs with 9 hidden neurons and 4 outputs which include the tensile strength, elongation, hardness and abrasive wear resistance gives reasonably accurate results with an error within the range of 2-7 % in training, testing and validation. The modeling results shows that an alloy contents 2-3 % Cu, 2-3 % Mg, 3-5 % Zn reinforced with 10 % Al 2 O 3 can successfully be developed for highest strength (297 MPa) and highest abrasive wear résistance (0.4 gm weight loss /15 minutes using stir casting method. The modeling results also suggest that it is possible to develop the highest strength 466 MPa tensile strength and highest abrasive wear resistance aluminum alloy based casting composite materials having the matrix composition of 6 % Si, 2 % Mg with 3 % Zn reinforced with 2-5 % Al 2 O 3 particles.