In this research, the influence of the parameters of Metallic wires in the foam cores of sandwich panels as a reinforcement to improve the bending properties of sandwich panels has been investigated. In this regard, the three parameters including the number of wires (on a scale of 1, 2, and 3 wires), wire material (aluminum, iron, and steel) and their diameter (0.75, 1, and 1.5 mm) as the effective input parameters and specific bending strength and modulus of the structure have been selected as the output parameters of the design of experiment. In order to evaluate the parameters after validating the numerical model using the built prototype, an experiment has been designed using the Mini Tab software (Taguchi method) and simulation of the proposed tests has been carried out using the Abaqus software.The results showed that the optimal sample with priority of strength to weight includes three steel wires on each side, with the diameter of one millimeter. Also, with the increase in the number and diameter of the wires, the strength has increased, but this relationship is not always correct when assessing the strength to the weight of the sample. Increasing the mechanical properties of the wire increases the overall strength of the structure, so that the bending strength of the sandwich panel reinforced with three steel wires rises by about 43%, the bending modulus by about 80%, the specific strength by weight by 21%, and the special bending modulus by about 54%.

Structural sandwich beams are widely used because of their high specific stiffness and strength, noise reduction, thermal insulation and impact energy absorption characteristics. Conventional manufacturing method of composite sandwich structures is completed by a separate adhesive joining stage by which the composite faces are joined to the core. In this investigation, liquid phase sintering in the Al-Zn alloy system was used in order to form a diffusion bond between Metallic foam and plate. Joining treatment was conducted at 610oC for 30 minutes in an inert atmosphere. The shear strength of the joint was measured to be about 4.8 kPa.

The purpose of this paper is to investigate the work hardening behavior and energy absorption characteristic of Metallic foams and functionally graded foam filled tubes, including single-, double-and triple-layer foams. Closed-cell A356 alloy and pure zinc foams are fabricated by casting method. The results illustrate that the Metallic foams show partially brittle compressive deformation associated with cell walls’ bending and tearing. A nonlinear asymptotic model, 𝜎 𝜎 = 𝜎 𝜎 0(1 − 𝜀 𝜀 )− 𝜌 𝜌 𝐹 𝐹 /𝜌 𝜌 𝑆 𝑆 , is proposed to represent the hardening behavior of Metallic foams and graded foam filled tubes as a function of relative density. The development of a complementary model, 𝜎 𝜎 = 𝜎 𝜎 0𝜀 𝜀 sin(𝑛 𝑛 𝑛 𝑛 𝑛 𝑛 ) + 𝜎 𝜎 0(1 − 𝜀 𝜀 )− 𝜌 𝜌 𝐹 𝐹 /𝜌 𝜌 𝑆 𝑆 , leads to a more accurate estimation of crushing response considering the stress oscillations, particularly for the A356 foam with high degrees of oscillation and multi-layered structures containing distinct plateau regions. Therefore, the present model is fairly consistent with the experimental results. Greater density and strength of the zinc foam compared to those of the A356 foam cause the highest total energy absorption of 581 J in the zinc foam filled tube and the highest specific energy absorption of 459. 2 J/(g/cm3) in the A356 foam filled tube. The presence of zinc foam results in the decrease of specific energy absorption. However, it plays a dominant role in adjusting the crash features of graded structures. The compressive properties of multi-layered structures can be controlled by varying the number and material of the layers at constant geometric features.

Metallic foams are a new category of metals with a porous structure which possess new mechanical, thermal, electrical and acoustic properties including low density with simultaneously high stiffness, and acoustic and thermal insulation. These materials are utilized as a sandwich core to decrease the structure total weight and also, energy absorption and damping. Wide range of Metallic foam application makes it necessary to develop a modeling method which can be used in the numerical study of the mechanical behavior of these materials. In this regard, a novel geometrical modeling approach is proposed to produce a geometrical model of the foam. This is based on subtracting spherical pores with a random size and random position from the solid sheet which makes a more realistic way of foam sheet modeling. Most of the prior approaches use a repeating unit cell structure. Thus, three algorithms, including progressive subtraction, incremental and random-based subtraction of the pores are presented and developed. The proposed model validation is carried out based on geometrical aspect and with the comparison of four parameters such as relative density, cell size ranges, distribution of cell sizes in the foam structure and mean cell sizes. Results show a close agreement between modeled foams with real ones. Also, geometrical study results that with an increase in the mean cell size, relative density first increases and then decreases.

Purpose: To identify the clinical features in eyes with non-Metallic and non-magnetic Metallic intraocular foreign bodies (IOFBs) and evaluate the results of surgical management in such patients referred to Labbafinejad Medical Center from 1987 to 2002. Methods: We reviewed the hospital records of a consecutive series of patients who had undergone vitrectomy due to IOFB extraction. Results: Thirty two eyes of twenty eight patients underwent vitrectomy and IOFB extraction. All IOFBs were removed with intraocular forceps, either through pars plana vitrectomy in 30 eyes (93.9%) or through a limbal groove in 2 eyes (6.1%). Average follow-up period was 7.5 months. The IOFBs were non-Metallic in 22 eyes (68.75%) including stone in 9 eyes (40.90%), glass in 7 eyes (31.81%), wood in 2 eyes (9.0.9%), and undetermined in 4 eyes (18.18%). Non-magnetic IOFBs were encountered non-magnetic Metallic in 10 eyes (31.25%) including copper in 7 eyes (70%), lead in 2 eyes (20%), and aluminum in 1 eye (10%). Of seven eyes with retained copper foreign bodies, 6 (85.7%) had signs of ocular chalcosis. Final visual acuity was 20/40 in 10 eyes (31.3%) and 5/200- 20/50 in 10 eyes (31.3%). In 7 eyes (21.7%), a retinal break was seen posterior to the sclerotomy at the final follow up examination. Preoperative retinal detachment was seen in 4 eyes (12.5%) and postoperative retinal detachment was observed in 2 cases. There was no significant relationship between final visual acuity of 20/200 or better and the type or size of non-Metallic and non-magnetic Metallic IOFBs. Conclusion: Performance of a meticulous vitrectomy is mandatory and an attempt should be made to minimize the rate of iatrogenic peripheral retinal breaks. The results of vitreous surgery for IOFB extraction are remarkably good.    

The aim of this study is to provide a method of making ultralight open cell copper foam with high surface area using chemical procedures. Among the various methods of making open-cell metal foams, electrodeposition method is selected because it can be done in a clean way and is cheaper than other methods. In this method, an open cell polyurethane sponge was used as substrate. Then by choosing appropriate chemical solutions with specific technical knowledge, first polyurethane surface has activated and then by electroless-deposition method, polyurethane activated surface covered with a thin layer of copper. In the final stage, with the aid of electrodeposition the thickness of copper layer was increased to the desired thickness with a minimum required strength. The results show that electrodeposition can increase the thickness of copper layer from 3-5 microns that is obtained in electroless-deposition method to above100 to 150 microns. SEM results show that the micro structure of the deposited layer is globular. By controlling the thickness of deposited copper in electroplating, the surface area of the copper foam can be increased. According to results optimum time for electroless-deposition is between 5 to 7 minutes and for electrodeposition is 1 hour. The open-cell copper foam that is produced in this research is ultralight and due to it high surface can transfer heat with high rates.