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News And Media HETL has registered six patents in Indian patent office on design and methods of OSAMC impleme -ntation. The product is already in test bench for certification and has a very high potential to use in Indian Aviation Industry.

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Hardware design & developments of OSAMC

The Open System Architecture Mission Computer (OSAMC) was conceptualized to be developed as an Open System Architecture design which could be used in different aircrafts with minimal changes in hardware configuration. The design was thus intended to comprise of 5-6 cards each of which would sit on a backplane and communicate with each other via the backplane.

The computer with multiple Power PC processors has various interfaces used in Aviation. The MIL-STD-1553B, ARINC-429, Gigabit Ethernet, USB 2.0, RS-422, Synchro, Discrete, Analog, video with various formats (like CVSB, DVI, PAL Y/C, STANAG 3350 B – RGB) etc. to name a few. Inter-processor communication uses PCI-Express protocol, capable of data transfer up to..... 10.0 GB/Sec, via industry standard VITA-46 backplane. The backplane also supports standard VME-Bus communication for Legacy system.

The processors are housed in individual carrier cards, each of which has facility to mount two standard PCI Mezzanine cards (daughter boards) via standard PMC connectors. It is also possible to mount standard XMC cards in case PCI-Express communication is required with the carrier card. These features make the architecture to be categorized as open type, making it feasible to plug-in specific hardware modules on requirement basis. At present, the functions that are materialized through PMC/ XMC are MIL-STD-1553B BCRTM (4 Channels), ARINC-429 (4 Tx/ 8 Rx), Graphics processing (2 graphics output), High volume flash memory (64 GB), Video conversion & switching (8 input & 8 output; 4 different formats), stroke symbol generation for Head Up Display (2 HUDs). The intelligent power module is also mounted on the backplane to generate required power for the hardware from the input supply received through connector (28 V DC & 115 V AC – 400 Hz).

The interfaces are terminated to a uniquely conceptualized Input/ Output transition panel which houses matching connectors to interface power supply, external connectors, signal conditioning, conversion of signals to digital form and routing of other signals. It is linked to the backplane through industry standard multi-pin connectors in such a way that the complete unit attains a cable-less configuration minimizing EMI/ EMC characteristics. OSAMC has been designed and developed complying to DO-178B for platform software, DO-254 for hardware, MIL-STD-810F for environmental and MIL-STD-217F for reliability standards. The ¾ ATR (short) chassis with 8 slots (for 6 U boards) has been designed to dissipate generated heat from boards by conduction to inner wall and henceforth by convection using cool airflow between side and top panels.

Hardware design & developments of SSHMS

Design and Development of Ultrasonic Non Destructive Evaluation and Testing based Smart Structural Health Monitoring System (SSHMS)

Overview
Nondestructive testing (NDT) is a noninvasive method to determine the integrity of a material, component or structure. While NDT is a qualitative analysis of the material for damage detection, Non Destructive Evaluation (NDE) is a quantitative measure. NDE is a method of analytically determining material properties like hardness, internal stress, elasticity and is useful for periodic in - service monitoring of flaw or damage growth. One of the major applications of NDE is in continuous inspection of structures for inherent damage detection, also known as Structural Health Monitoring.

Structural Health Monitoring (SHM) is the ability to detect and interpret the adverse changes in a material in order to improve reliability and reduce the life cycle cost.

The problem is of detecting and characterizing defects (damages) in any structure. The defects come in various forms and sizes, and could be located anywhere in the structure. The basic idea is to pump acousto-ultrasonic pressure wave into the structure at one or more points and collecting the ultrasound signal at one or more points. These collected signals can be analyzed to characterize the defect. Furthermore, some of the defects types that are proposed to be detected and identified can be categorized as following

Defect Categories
Following are the categories of defects that need to be analyzed:
1. Cracks
2. Holes
3. De-laminations
4. Voids

Setup of the Developed Structural Health monitoring system

Experimental Results

Figure: Sample signal 100mm center distance NO FLAW

Figure: Sample signal 100mm center distance with FLAW

For more detail, please download the brochure SAOHMS Brochure

SSHMS: Smart Structural Health Monitoring System

Structural Health Monitoring (SHM)

SHM can play a vital role in systems where lives and investments are at stake. It is a huge advantage to identify when the structural flaws start manifesting themselves in the form of fatigue or micro-cracks. Having identified a flaw early enough, preventive maintenance can be carried out and the life of the structure can be extended, resulting in a lot of monetary savings and guaranteed safety assurance.

Ultrasound-based NDT

Ultrasound waves find heavy application in non-destructive testing. Apart from the bulk waves (longitudinal and transverse waves), there are a number of other modes possible, of which the most interesting ones are called lamb waves (also called plate waves or guided waves). Lamb waves are born out of interference of transmitted and reflected bulk waves between the surfaces. Hence, they are possible only in thin plates which are only a few wavelengths thick. There are basically two modes of lamb waves possible – symmetric and asymmetric, where the symmetric nature is with respect to the mid-thickness plane. The basic modes that exist at all frequencies are S0 and A0, the zero-order modes. Depending on the product of plate thickness and frequency of excitation, higher modes of symmetric and asymmetric modes are possible.

Transducer Design

Transducer design is primarily based on the characteristics of material under test, the type of flaw to be investigated, and the lamb wave modes that are to be induced. We have designed a piezo-ceramic transducer that has a center frequency of 250 KHz and it induces the S0 and A0 modes in aluminum plates.

Physical Dimensions:
10 mm diameter0.2 mm thickness

Packaging Technology

The transducers are mounted on a special conductive silver epoxy paste. The base material is a 0.100 micron heat stabilized polycarbonate sheet. Conductive inks used are silver, carbon and silver-carbon blendsconductive in printed tracks for connections with resistance of tracks less than2 ohms.

Feature Extraction

The transducer output signals are collected for various normal and flaw conditions. The signal characteristics can be examined for flaw signature. The characteristics of interest become the features that can be monitored to determine the characteristics of the flaw. Digital processing techniques like discrete fourier transform and wavelet transform are used to extract the features from the output signals.

Ongoing Effort

Digital signal processing techniques like discrete fourier transform and wavelet transform are being used to identify the signal characteristics that could be used as features for pattern recognition. Artificial neural networks will be used to solve the non-linear problem of multi-feature space partitioning and determine flaw characteristics.