MEC 100INTRODUCTION TO

MECHANICALENGINEERING

PREPARED FOR:GHAZIRAH MUSTAPHA

PREPARED BY:

MOHAMAD ADIB BIN MOHAMAD SANUSI [2009 60 2112]FAKHRULLAH AZIZI BIN AHMAD [2009 40 2328]ABDUL BASIR BIN ILYAS [2009 40 3048]AMIRUL HAZIQ BIN NASRUDDIN (2009 42 7394)

What Makes a Failure Into an "Engineering Disaster"?

Much of the reason why we consider an engineering failure to be an engineering "disaster" has to do with

public perception of risk. For example, in 1992 roughly the same number of fatalities occurred (in the United

States) in transportation accidents involving airplanes (775), trains (755), and bicycles (722). Yet the public

perception of the risk associated with air travel is often much higher than that for trains and certainly for

bicycles. This stems from two reasons: (1) the large loss of life (and associated wide spread news reporting)

resulting from a single air crash, and (2) the air passenger's lack of control over their environment in the case

of air or, to a lesser degree, rail accidents. Both of these reasons results in increased fear, and hence a

higher degree of perceived risk.

Primary Causes of Engineering Disasters

The primary causes of engineering disasters are usually considered to be

human factors (including both 'ethical' failure and accidents)

design flaws (many of which are also the result of unethical practices)

materials failures

extreme conditions or environments, and, most commonly and importantly

combinations of these reasons

A recent study conducted at the Swiss federal Institute of technology in Zurich analyzed 800 cases of

structural failure in which 504 people were killed, 592 people injured, and millions of dollars of damage

incurred. When engineers were at fault, the researchers classified the causes of failure as follows:

    Insufficient knowledge ...................................... 36%

Underestimation of influence ........................... 16%

Ignorence, carelessness, negligence ............... 14%

Forgetfulness, error .......................................... 13%

Relying upon others without sufficient control .... 9%

Objectively unknown situation ............................ 7%

Unprecise definition of responsibilities .............. 1%

Choice of bad quality .......................................... 1%

Other ................................................................... 3%

M. Matousek and Schneider, J., (1976) Untersuchungen Zur

Struktur des Zicherheitproblems bei Bauwerken, Institut

für Baustatik und Konstruktion der ETH Zürich,

Bericht No. 59, ETH.

   

Engineering Ethics

Often, a deficiency in engineering ethics is found to be one of the root causes of an engineering failure. An

engineer, as a professional, has a responsibility to their client or employer, to their profession, and to the

general public, to perform their duties in as conscientious a manner as possible. Usually this entails far more

than just acting within the bounds of law. An ethical engineer is one who avoids conflicts of interest, does not

attempt to misrepresent their knowledge so as to accept jobs outside their area of expertise, acts in the best

interests of society and the environment, fulfills the terms of their contracts or agreements in a thorough and

professional manner, and promotes the education of young engineers within their field. Many of these issues

are discussed in detail at the ethics homepage of the National Society of Professional Engineers. There you

will find an example of an engineering Code of Ethics and links to additional information on engineering

ethics. Or check here our list of some codes of Engineering Ethics. Failures in engineering ethics can have

many legal consequences as well, as in the case of a mall collapse in Korea.

Thirty five faculty members from around the country have created a number of case problems in several

engineering disciplines which intertwine technical calculations with engineering ethics. These were presented

at a 1995 workshop at Texas A&M, sponsored by the National Science Foundation.

The site for Applied Ethics in Professional Practice Case of the Month Club created and maintained by then

Professional Engineering Practice Liaison Program in the College of Engineering at University of Washington,

provides the opportunity to review a particular case study which involves engineering ethics and then vote on

which course of action should be taken. All cases are based on actual professional engineering experiences

as contributed by a board of practicing engineers nationally. Background information on codes of ethics is

also provided at this site.

FAMOUS ENGINEERS

Jack Kilby

There are few men whose insights and professional accomplishments have changed the

world. Jack Kilby was one of these men. His invention of the monolithic integrated circuit - the

microchip - laid the conceptual and technical foundation for the entire field of modern

microelectronics. From Jack Kilby's first simple circuit has grown a worldwide integrated

circuit market whose sales in 2007 totaled $219 billion.

About Jack

Jack Kilby grew up in Great Bend, Kansas and joined TI in Dallas in 1958. During the summer

of that year, working with borrowed and improvised equipment, he conceived and built the

first electronic circuit in which all of the components, both active and passive, were fabricated

in a single piece of semiconductor material half the size of a paper clip.

The Chip that Jack Built

It was a relatively simple device that Jack Kilby showed to a handful of co-workers gathered in

TI's semiconductor lab 50 years ago -- only a transistor and other components on a slice of

germanium. Little did this group of onlookers know that Kilby's invention was about to

revolutionize the electronics industry.

What If He Had Gone on Vacation

"As a new employee, I had no vacation time coming and was left alone to ponder the results

of the IF amplifier exercise. The cost analysis gave me my first insight into the cost structure

of a semiconductor house."

Nobel Prize

Jack Kilby received the Nobel Prize in Physics on December 10. 2000 for his part in the

invention of the integrated circuit. To congratulate him, U.S. President Bill Clinton wrote, "You

can take pride in the knowledge that your work will help to improve lives for generations to

come."

BEM (THE BOARD OF ENGINEERS MALAYSIA)

The Board of Engineers Malaysia (BEM) is a statutory body constituted under the Registration

of Engineers Act 1967 with perpetual succession and a common seal and which may sue and

be sued. It was formed in 23rd August 1972.

BEM falls within the ambit of responsibility of the Minister of Works. Vested with wide powers,

the Minister may suspend the operation of the Registration of Engineers Act 1967 in any part

of Malaysia by notification in the gazette. The appointment of the Board Members and the

Registrar is made by the Minister. Last but not least, the Minister has the final say on any

appeal from foreign engineers who are not satisfied with the decision of the Board in rejecting

their applications for temporary registration or renewal.

Functions of BEM

BEM is of the view that it plays a pivotal role in uplifting the image of the engineering

profession. In order that it may play its role effectively, BEM is carrying out in earnest its

various functions provided for in Section 4 of the Registration of Engineers Act 1967

(Amendment 2002). The functions are:

a)  Maintaining the Register

The Board shall keep and maintain a Register which shall be in five Parts:

Part A - which shall contain the names, addresses and other particulars of Professional

Engineers;

Part B - which shall contain the names, addresses and other particulars of Graduate

Engineers;

Part C - which shall contain the names, addresses and other particulars of Temporary

Engineers;

Part D - which shall contain the names, addresses and other particulars of Engineering

consultancy practices; and

Part E - which shall contain the names, addresses and other particulars of Accredited

Checkers.

b)  Processing Applications for Registration

BEM through its Examination and Qualification Committee conducts the Professional

Assessment Examination (PAE) to assess the quality of experience gained by the Graduate

Engineers and his competency.

Every application for registration, be it as Graduate Engineers, Professional Engineers,

Engineering Consultancy Practices or Temporary Engineers by foreign engineers is

scrutinized thoroughly by the Application Committee to ensure compliance with the Act and

with the policy of BEM.

BEM also applies restrictions on practices of bodies corporate with the aim that engineering

consulting services provided by these bodies corporate would be done professionally for the

benefit of the client/public. Restrictions also imposed to Temporary Engineers.

c)  Assessment of Academic Qualifications

BEM through its Engineering Accreditation Council (EAC)* assesses and accredits

engineering degrees offered by institutions of higher learning. This is done by forming an

accreditation team whose members are appointed by EAC. The accreditation team shall

consist of at least three members in the same or related discipline of the course to be

accredited. At least one of the members should be from an academic institution and one from

industry/practice. The accreditation team shall visit the institution to audit the facilities and

have dialogue with academic staff and students.

There are two types of accreditation given by BEM:  conditional accreditation and full

accreditation.  The period of full accreditation shall be five years after which it has to be

revalidated.  Where there are minor shortcomings in meeting the accreditation

requirement, the programme may be given conditional accreditation for a period of not

more than 2 years during which the faculty must take necessary corrective measures.

BEM use as a guide the list for Professional/Chartered Engineer by the accreditation

organisations of the country where the degree is issued.  

Prior to conduct new engineering programme institution of higher learning shall obtain

approval from the relevant authorities.   The authority normally will require supporting

document from EAC.

* The Engineering Accreditation Council is the co-ordinating body on accreditation,

representing the Board of Engineers Malaysia, the Institution of Engineers Malaysia,

Lembaga Akreditasi Negara (LAN) andJabatanPerkhidmatan Awam Malaysia (JPA).

 

d)  Regulating the Conduct and Ethics of the Engineering Profession

Since its inception in 1972, BEM has been a medium for the engineers to decide on matters

relating to their professional conduct or ethics. Any matter concerning the professional

conduct of registered engineers will be studied by the Board to determine whether there is a

breach of professional ethics or code.

If the need arises, BEM will carry out investigations to establish whether there is a prima facie

case against a registered engineer for contravening the Act. The procedures to follow are

prescribed in Section 15 of the Act.

If there is a breach of professional ethics or code of conduct on the part of the engineer but

such breach is not serious enough to warrant suspension or cancellation of registration,

appropriate action, e.g. warning, censure or advice would be taken by BEM as deemed fit.

Such measures should be viewed by the engineers at large as a concerned effort on the part

of BEM to rid the black sheep of the engineering fraternity.

 

e)  Scale of Fees

In this respect the Scale of Fees Committee of BEM continues to have dialogues sessions

with the Federal Treasury on issues involving mode of remuneration, quantum and conditions

of payment.

f)  Publication

The Publication Committee of BEM undertakes the task of promoting engineering profession

through Buletin Ingenieur and other printed materials.

The Ingenieur (4 issues per year: March, June, Sept and December) is used as a 

communication tool for BEM to disseminate information on the activities of the Board,

regulations, code of ethics, career development, update and guidelines and such other news

as decided by the Board.  

g)  Promotion of Continued Learning and Education,

BEM has set certain guidelines in connection with the financial assistance provided.

BEM will consider providing financial assistance to seminar or conference which is organised

by a non-profit making organisation. The seminar or conference must be technical one that

will benefit the registered engineers.

The promotion of continued learning and education does not stop here. BEM would also

consider giving grant to selected type of study related to engineering or contribute prizes for

selected competition also related to engineering. BEM even goes further by purchasing

engineering reference books which all engineer have access to in the BEM library.

In order to keep abreast with changing techology, BEM encourages all registered engineers

to continually improve themselves through Continuous Professional Development (CPD)

Programme. 

 

INTRODUCTION TO IEM (INSTITUTE OF ENGINEERS MALAYSIA)

The Institution of Engineers, Malaysia better known as the IEM. It is a professional learned

society serving more than 16,000 members in Malaysia, overseas and the communities in,

which they work. It was formed in 1959 and was admitted a member of the Commonwealth

Engineers Council in 1962. The Institution is a qualifying body for professional engineers in

Malaysia. 

With a membership of close to 24,094 engineers and an estimated annual growth rate of

10%, IEM is one of the largest professional body in Malaysia.

The Corporate member of the Institution can apply to the Board of Engineers, Malaysia

(which is a registration body) for registration as a Professional Engineer, which will entitle him

to set up practice.  The qualification standards are determined by the Council of the

Institution. 

The Institution is one of the few professional engineering institutions in the world, which

represents all disciplines of the profession, and is thus able to take a broad view of the

professional scene.

Currently, the IEM has five (5) official representatives on the BEM out of a total Board

membership of seventeen (17). 

IEM'S FUNCTIONS

Objective

To undertake activities related to the promotion and advancement of the science and

engineering aspect of tunnelling and underground space technologies both locally and

internationally.

IEM is a society established to promote and advance the Science and Profession of

Engineering in any or all its disciplines and to facilitate the exchange of information and ideas

related to Engineering.

Function;

Gain recognition for engineering experience and professional accomplishments.

Get assessed on proficiency to qualify for registration as a Professional Engineer.

Access to a wide network of fellow engineers in the private and public sectors in

Malaysia as well as regional and international engineering bodies.

Advance professional development by attending regurlarly organised in-house talks,

external conference and site visits.

Keep abreast with engineering development via readership of IEM Journals and

Bulletins.

Formal recognition of your profession.

Provides an avenue for networking with other engineers outside your company and

also an opportunity to meet industry leaders.

Corporate members of IEM are accepted for registration as a professional engineer

with the Board of Engineers Malaysia.

Provide participation in continuing education through seminars, workshops,

conferences, talks, forums, courses, etc.

A strong secretariat to support needs of members and provide guidance.

Receive monthly and quarterly publications.

Access to a well equipped library.

Linked to the internet and access to the information superhighway, via internet.

Establish relationship with other professional bodies concerning matters of mutual

interest.

Opportunity to be sponsored by IEM to present papers in national and/or international

conferences.

THE TACOMA NARROW BRIDGE

The original Tacoma Narrows Bridge was opened to traffic on July 1, 1940. It was located in

Washington State, near Puget Sound.

The Tacoma Narrows Bridge was the third-longest suspension bridge in the United States at

the time, with a length of 5939 feet including approaches. Its two supporting towers were 425

feet high. The towers were 2800 feet apart.

Prior to this time, most bridge designs were based on trusses, arches, and cantilevers to

support heavy freight trains. Automobiles were obviously much lighter. Suspension bridges

were both more elegant and economical than railway bridges. Thus the suspension design

became favored for automobile traffic. Unfortunately, engineers did not fully understand the

forces acting upon bridges. Neither did they understand the response of the suspension

bridge design to these poorly understood forces.

Furthermore, the Tacoma Narrows Bridge was built with shallow plate girders instead of the

deep stiffening trusses of railway bridges. Note that the wind can pass through trusses. Plate

girders, on the other hand, present an obstacle to the wind.

As a result of its design, the Tacoma Narrows Bridge experienced rolling undulations which

were driven by the wind. It thus acquired the nickname "Galloping Gertie."

FAILED???

Strong winds caused the bridge to collapse on November 7, 1940. Initially, 35 mile per hour

winds excited the bridge's transverse vibration mode, with an amplitude of 1.5 feet. This

motion lasted 3 hours.

The wind then increased to 42 miles per hour. In addition, a support cable at mid-span

snapped, resulting in an unbalanced loading condition. The bridge response thus changed to

a 0.2 Hz torsional vibration mode, with an amplitude up to 28 feet. The torsional mode is

shown in Figures 1a and 1b.

Figure 1a. Torsional Mode of the Tacoma Narrows Bridge

Figure 1b. Torsional Mode of the Tacoma Narrows Bridge

The torsional mode shape was such that the bridge was effectively divided into two halves.

The two halves vibrated out-of-phase with one another. In other words, one half rotated

clockwise, while the other rotated counter-clockwise. The two half spans then alternate

polarities. One explanation of this is the "law of minimum energy." A suspension bridge may

either twist as a whole or divide into half spans with opposite rotations. Nature prefers the two

half-span option since this requires less wind energy.

The dividing line between the two half spans is called the "nodal line." Ideally, no rotation

occurs along this line.

The bridge collapsed during the excitation of this torsional mode. Specifically, a 600 foot

length of the center span broke loose from the suspenders and fell a distance of 190 feet into

the cold waters below. The failure is shown in Figures 2a and 2b.

Figure 2a. Failure of the Tacoma Narrows Bridge

Figure 2b. Tacoma Narrows Bridge after the Failure

WHY TACOMA NARROW BRIDGE (GALLOPING GERTIE) COLLAPSE???

Besides Tacoma Bridge is the greatest bridge in that time, but it collapse on 7 November

1940. The tragedy become an issue because the Tacoma Narrow Bridge collapse less than a

year from the building.

The Federal Works Administration (FWA) appointed a 3-member panel of top-ranking

engineers: Othmar Amman, Dr. Theodore Von Karmen, and Glen B. Woodruff. Their report

was the Administrator of the FWA, John Carmody and became known as the "Carmody

Board" report.

And the report says:"Random action of turbulent wind"

They also said all engineer must study more about the nature and also aerodynamic to avoid

this tragedy repeat.

Engineers still debate the exact cause of its collapse, however. Three theories are:

1. Random turbulence

An early theory was that the wind pressure simply excited the natural frequencies of

the bridge. This condition is called "resonance." The problem with this theory is that

resonance is a very precise phenomenon, requiring the driving force frequency to be

at, or near, one of the system's natural frequencies in order to produce large

oscillations. The turbulent wind pressure, however, would have varied randomly with

time. Thus, turbulence would seem unlikely to have driven the observed steady

oscillation of the bridge.

2. Periodic vortex shedding

Theodore von Karman, a famous aeronautical engineer, was convinced that vortex

shedding drove the bridge oscillations. A diagram of vortex shedding around a

spherical body is shown in Figure 3. Von Karman showed that blunt bodies such as

bridge decks could also shed periodic vortices in their wakes.

A problem with this theory is that the natural vortex shedding frequency was

calculated to be 1 Hz. This frequency is also called the "Strouhal frequency." The

torsional mode frequency, however, was 0.2 Hz. This frequency was observed by

Professor F. B. Farquharson, who witnessed the collapse of the bridge. The

calculated vortex shedding frequency was five times higher than the torsional

frequency. It was thus too high to have excited the torsional mode frequency.

In addition to "von Karman" vortex shedding, a flutter-like pattern of vortices may

have formed at a frequency coincident with the torsional oscillation mode. Whether

these flutter vortices were a cause or an effect of the twisting motion is unclear.

Figure 3. Vortex Shedding around a Spherical Body

3. Aerodynamic instability (negative damping)

Engineers needed to test suspension bridge designs using models in a wind tunnel.

Aerodynamic instability is a self-excited vibration. In this case, the alternating force

that sustains the motion is created or controlled by the motion itself. The alternating

force disappears when the motion disappears. This phenomenon is also modeled as

free vibration with negative damping.

More reason of Galloping Gertie collapse are:

1. The fundamental weakness

Said a summary article published in Engineering News Record, was its "great

flexibility, vertically and in torsion." Several factors contributed to the excessive

flexibility: The deck was too light. The deck was too shallow at 8 feet (a 1/350 ratio

with the center span). The side spans were too long, compared with the length of the

center span. The cables were anchored at too great a distance from the side spans.

The width of the deck was extremely narrow compared with its center span length, an

unprecedented ratio of 1 to 72.

2. The pivotal event in the bridge's collapse

Said the Board, was the change from vertical waves to the destructive twisting,

torsional motion. This event was associated with the slippage of the cable band on the

north cable at mid-span. Normally, the main cables are of equal length where the mid-

span cable band attaches them to the deck. When the band slipped, the north cable

became separated into two segments of unequal length. The imbalance translated

quickly to the thin, flexible plate girders, which twisted easily. Once the unbalanced

motion began, progressive failure followed.

3. Torsional flutter

"Flutter" is a self-induced harmonic vibration pattern. This instability can grow to very

large vibrations.

Tacoma Narrows Failure Mechanism - original sketch contributed by Allan Larsen

4. The bridge movement changed

When the bridge movement changed from vertical to torsional oscillation, the

structure absorbed more wind energy. The bridge deck's twisting motion began to

control the wind vortex so the two were synchronized. The structure's twisting

movements became self-generating. In other words, the forces acting on the bridge

were no longer caused by wind. The bridge deck's own motion produced the forces.

Engineers call this "self-excited" motion.

5. The two types of instability, vortex shedding and torsional flutter occurred at

relatively low wind speeds.

It was critical that the two types of instability, vortex shedding and torsional flutter,

both occurred at relatively low wind speeds. Usually, vortex shedding occurs at

relatively low wind speeds, like 25 to 35 mph, and torsional flutter at high windspeeds,

like 100 mph. Because of Gertie's design, and relatively weak resistance to torsional

forces, from the vortex shedding instability the bridge went right into "torsional flutter."

6. The bridge was beyond its natural ability

Now the bridge was beyond its natural ability to "damp out" the motion. Once the

twisting movements began, they controlled the vortex forces. The torsional motion

began small and built upon its own self-induced energy. In other words, Galloping

Gertie's twisting induced more twisting, then greater and greater twisting. This

increased beyond the bridge structure's strength to resist. Failure resulted.

OVERCOME OF THE FAILURE OF TACOMA NARROW BRIDGE (GALLOPING GERTIE).

The deck system's prominent 33-foot deep steel Warren stiffening trusses: These gave the bridge a depth-to-center span ratio of 1 to 85, the deepest stiffening system on a major suspension span since the 1909 Manhattan Bridge.

 View of 1950 Narrows Bridge's 33-foot deep Warren truss WSDOT

Double (top and bottom) lateral bracing of the stiffening trusses:This feature, combined with the 33-foot deep stiffening truss, gave the bridge exceptional torsional rigidity. 

Wind grates: Three slots of open steel grating 33 inches wide separating all four traffic lanes, and a strip 19 inches wide along each curb. 

Hydraulic shock absorbers at three strategic points in the structure:

(1) at mid-span, at the main cable center tie, between the main suspension cables and the top of the stiffening truss; 6 devices per cable (a "first" for a long suspension bridge);   (2) between the top chords of the main span and side span stiffening trusses; and   (3) at each tower, where it joins the bottom of the deck truss.

Ends of the west and east side spans were anchored securely to the ground. 

Cable sag ratio of 1:12. This required the towers to be higher than the 1940 bridge, which had a sag ratio of 1:10.

Setting tower base plate, 1948 WSDOT

DESIGNER OF GALLOPING GERTIE

Leon Moisseiff (1872-1943)

1. The lead designer of the 1940 Tacoma Narrows Bridge, Leon

Salomon Moisseiff, was at the peak of his engineering profession

when the ill-fated span collapsed into the chilly waters of Puget

Sound that November day. Born in 1872 in Latvia, Moisseiff at the

age of 19 moved to New York with his parents. The talented young

engineer graduated from Columbia University in 1895. Only three

years later, he joined the New York City Bridge Department.

Moisseiff helped design and build some of the world's largest suspension bridges,

beginning with the 1909 Manhattan Bridge over the East River. He published an

article about his work on the Manhattan Bridge that promptly won him national

acclaim as the leading proponent of the "deflection theory," which he introduced from

Europe.

2. Moisseiff's elaboration of the "deflection theory" laid the groundwork for three

decades of long-span suspension bridges that became lighter and narrower. These

bridges were not only more "graceful" and beautiful to the public and to engineers at

the time, they also were cheaper to build, because they used far less steel than

earlier spans. Moisseiff became a private consultant and was involved in the design

of almost every major suspension bridge built in the 1920s and 1930s.

3. The culmination of Moisseiff's work was the 1940 Tacoma Narrows Bridge. He called

it the "most beautiful" bridge in the world. Unfortunately, Moisseiff had entirely

overlooked the importance of aerodynamics in his bridge designs. As they became

lighter and narrower, they became more flexible and unstable.

4. When Galloping Gertie collapsed, Clark Eldridge publicly pointed the finger at

Moisseiff. Eldridge believed that Moisseiff unethically approached the Public Works

Administration and convinced them to require Washington State to hire Moisseiff, to

review the design that Eldridge had prepared.

5. He was contacted immediately after the failure, said he was "completely at a loss to

explain the collapse." Moisseiff visited the ruined bridge one week later, touring under

the watchful eye of Clark Eldridge. Moisseiff's design, while pushing beyond the

boundaries of engineering practice, fully met the requirements of accepted theory at

the time.

6. Moisseiff's other professional colleagues exonerated him. Still, the disaster effectively

ended his career. His health had been compromised since 1935, when he suffered a

heart attack. He died at age 71 on September 7, 1943, just three years after failure of

his "most beautiful" bridge.

7. In recognition of his contributions to the engineering profession, the American Society

of Civil Engineers State to establish the Moiseff Award Fund.

WHAT HE HAD DONE??

1. He doesn’t know about the new suspension of bridge design will react to natural

force.

2. He use the wrong technic to build a bridge. This because he not study the effect of

natural phenomena with the design of the building.

3. He also neglect the importance of Tacoma Narrow Bridge aerodynamic to allow the

wind flow through the bridge without any disruption.