1966 CHEVELLE STEERING WHEEL

Geomechanics of Failures

The main goal of this introductory course is to demonstrate how basic concepts in soil mechanics can be used as a "forensic" tool in the investigation of geotechnical failures. This, in turn, provides a good opportunity to show how to use available procedures in the formulation of useful simple geotechnical models. Geotechnical failure is understood here in a broad sense as the failure of a structure to function properly due to a geotechnical reason. Some of the geotechnical failures selected are well known for their impact on the geotechnical community. Others are closer to the authors' experience. They have been organized into three main topics: Settlement, Bearing Capacity and Excavations. They cover a significant proportion of every day activities of professional geotechnical engineers. No attempt has been made to create a comprehensive handbook of failures. Instead, the emphasis has been given to creative applications of simple mechanical concepts and well known principles and solutions of Soil Mechanics. The book shows how much can be learned from relatively simple approaches. Despite this emphasis on simplicity, the book provides a deep insight into the cases analyzed. A non-negligible number of new analytical closed-form solutions have also been found. Their derivation can be followed in detail. In all the cases described an effort was made to provide a detailed and step by step description of the hypothesis introduced and of the analysis performed. Each of the eight chapters of the book addresses a certain type of failure, illustrated by a case history. The chapters are self-contained. They provide a review of soil mechanics principles and methods required to understand and explain the failure described. In some cases the analysis offered provides a non-conventional application of basic principles. All chapters are completed with a summary of lessons learned from the failure and its analysis. They also include a short account on advanced topics to help the interested readers to go beyond the approaches used in the book. Readers are expected to be familiar with the basic concepts of soil mechanics and foundation engineering. The target audience is graduate students, faculty and practicing professionals in the fields of civil and geotechnical engineering. This textbook profits from experience accumulated in teaching a course in forensic engineering at the ETH Zurich.

The Thames Tunnel is an underwater tunnel, built beneath the River Thames in London, United Kingdom, connecting Rotherhithe and Wapping. It measures 35 feet (11 m) wide by 20 feet (6 m) high and is 1,300 feet (396 m) long, running at a depth of 75 feet (23 m) below the river's surface (measured at high tide). It was the first tunnel known successfully to have been constructed underneath a navigable river, and was built between 1825 and 1843 using Thomas Cochrane[citation needed] and Marc Isambard Brunel's newly invented tunnelling shield technology, by him and his son Isambard Kingdom Brunel.
The tunnel was originally designed for, but never used by, horse-drawn carriages and was most recently used by trains of the London Underground's East London Line. The East London Line closed on 23 December 2007 to allow extension of the line and conversion of the route to become part of the London Overground network in time for 2010.

At the start of the 19th century, there was a pressing need for a new land connection between the north and south banks of the Thames to link the expanding docks on both sides of the river. The engineer Ralph Dodd tried, but failed to build a tunnel between Gravesend and Tilbury in 1799.
In 1805–1809 a group of Cornish miners, including Richard Trevithick, attempted to dig a tunnel further upriver between Rotherhithe and Wapping but failed because of the difficult conditions of the ground. The Cornish miners were used to hard rock and did not modify their methods for soft clay and quicksand. The "Thames Archway" project was abandoned after it caved in when 1,000 feet (305 m) of a total of 1,200 feet (366 m) had been dug.[3] However, even if it had been completed its usefulness would have been questionable; it only measured 2–3 feet by 5 feet (61–91 cm by 1.5 m), far too small for passenger use.
The failure of the Thames Archway project led engineers to conclude that "an underground tunnel is impracticable". However, the Anglo-French engineer Marc Brunel refused to accept this conclusion. In 1814 he proposed to Tsar Alexander I of Russia a plan to build a tunnel under the river Neva in St Petersburg. This scheme was turned down (a bridge was built instead) but Brunel continued to develop ideas for new methods of tunnelling.
Brunel and Thomas Cochrane patented the tunnelling shield, a revolutionary advance in tunnelling technology, in January 1818. In 1823 Brunel produced a plan for a tunnel between Rotherhithe and Wapping, which would be dug using his new shield. Financing was soon found from private investors including the Duke of Wellington and a Thames Tunnel Company was formed in 1824, with the project beginning in February 1825.
The first step taken was the construction of a large shaft on the south bank at Rotherhithe, 150 feet (46 m) back from the river bank. It was dug by assembling an iron ring 50 feet (15 m) in diameter above ground. A brick wall 40 feet (12 m) high and 3 feet (91 cm) thick was built on top of this, with a powerful steam engine surmounting it to drive the excavation's pumps. The whole apparatus was estimated to weigh 1,000 tons. The soil below the ring's sharp lower edge was removed manually by Brunel's workers. The whole shaft thus gradually sank under its own weight, slicing through the soft ground rather like an enormous pastry cutter. The shaft became stuck at one point during its sinking as the pressure of the earth around it held it firmly in position. Extra weight was required to make it continue its descent; a total of 50,000 bricks were added as temporary weights. It was realised this problem was caused because the shaft was cylindrical; years later when the Wapping shaft was built, it was slightly wider at the bottom than the top. This non-cylindrical tapering design ensured it did not get stuck. By November 1825 the Rotherhithe shaft was in place and tunnelling work could begin.
The tunnelling shield, built at Henry Maudslay's Lambeth works and assembled in the Rotherhithe shaft, was the key to Brunel's construction of the Thames Tunnel. The Illustrated London News described how it worked:

The mode in which this great excavation was accomplished was by means of a powerful apparatus termed a shield, consisting of twelve great frames, lying close to each other like as many volumes on the shelf of a book-case, and divided into three stages or stories, thus presenting 36 chambers of cells, each for one workman, and open to the rear, but closed in the front with moveable boards. The front was placed against the earth to be removed, and the workman, having removed one board, excavated the earth behind it to the depth directed, and placed the board against the new surface exposed. The board was then in advance of the cell, and was kept in its place by props; and having thus proceeded with all the boards, each cell was advanced by two screws, one at its head and the other at its foot, which, resting against the finished brickwork and turn

Corvette Brakes...some history and tips.

From the time of the first V-8 installation in the early 1950’s, Corvettes out-performed their drum brakes. Finned drums, cool air ducts, Metallic lining, and power assists only gave marginal improvements. It only took a few high-speed brake applications to induce fade, better known as “goodbye asphalt, hello tire wall!” Finally, Zora Duntov’s team gave the 1965 Sting Ray some real stopping power – disc brakes! This system demonstrated straight, predictable stops time after time and was self-adjusting. It does have a few weak points that can cause today’s Corvette owner considerable headaches and expense. However, most of these problems can be remedied once they are pinpointed.

Beyond the Corvette Disc Brake innovation, the chosen caliper design was quite complex. Each Corvette Brake Caliper employs 4 pistons; 2 inboard and 2 outboard that enlists Pascal's Law to insure that equal brake pad pressure is exerted on each face of the Corvette Brake Rotor. So what's this stuff leaking on the garage floor? By design the Corvette Brake System is handicapped by the simple fact that there are 32 or more potential locations for fluid leaks to develop.
In addition; the cast iron construction of the caliper and its 4 piston bores is prone to rust and corrosion build-up which causes pits or irregularities to form in the cylinder wall and a failure of one or more of the piston seals. This may be corrected by honing the cast iron piston bores and replacing the seals but eventually this scenario will recur. A more permanent cure is replacement with Stainless Steel Sleeved Calipers. Each of the piston bores is lined with a stainless steel sleeve that resists virtually all rust and corrosion issues. Aging and breakdown of the rubber piston seals will eventually cause leaks to develop even within the stainless bores but lifetime is increased exponentially. Seal replacement alone would correct this problem, never scuff or hone a stainless steel sleeved caliper bore. Caliper leaks also tend to be more common on cars that are inactive or stored for extended periods of time. Occasional pumping of the brake pedal in these cars can help the dormant seals to remain limber and prevent them from sticking to the piston bore.

The brake fluid itself can cause problems. Most owners change the motor oil on a regular basis, but never think about the brake fluid until they experience a problem. Corvettes that sit idle for long periods should have their brake fluid replaced every two years or so. This will avoid the damage caused by water condensing within the brake system resulting in corrosion and leaks. An alternative is to drain the system and replace the fluid with silicone brake fluid. Silicone brake fluid does not have an affinity for water and helps to preserve internal brake parts and seals.

Occasionally old, weak brake caliper hoses will balloon under pressure and cause a spongy response in the brake pedal. Some owners report that, despite repeated bleedings, the brake pedal soon “goes soft” due to air in the system. This is most often caused by worn or mis-adjusted wheel bearings, warped ("out-of-true") rotors, a bent spindle face, or any combination of these faults. Each of these faults result in brake rotor run out which causes an alternating pumping action of the inboard and outboard caliper pistons as the car is driven. This caliper piston pulsing causes air to enter the system without fluid loss. Here, the only solution is to correct the cause of the rotor runout. The maximum allowance for rotor runout for the 1963-82 Corvette is .008". Lathing or "turning" the rotors may help but does nothing to correct the other causes mentioned earlier. Never "turn" the Corvette Brake Rotors beyond the minimum thickness which is stamped on the perimeter.

Occasionally, one wheel will start dragging or pulling due to a caliper piston “hanging up”. This situation has two main causes and remedies. A worn piston and bore may allow the piston to wedge itself in the bore and not retract when brake pressure is released. A defective rubber brake line can balloon or collapse internally and maintain pressure even after the brake pedal is released. A quick diagnosis is to carefully open the bleeder valve on the stuck caliper. If the brake line has trapped pressure, there will be a rush of fluid and the caliper should be freed. If the piston is jammed mechanically, there will be little, if any, fluid and the caliper will remain jammed. The owner will now know where to start on repairs.

Another common complaint is that either the front or rear calipers function, but the owner cannot get fluid to the other calipers. Once the master cylinder is checked and determined to function properly, the proportioning valve is usually the culprit. This is the rectangular block found between the master cylinder and the lines to the calipers. It’s main function is maintaining

Component failures result from a combination of factors involving materials science, mechanics, thermodynamics, corrosion, and tribology. With the right guidance, you don’t have to be an authority in all of these areas to become skilled at diagnosing and preventing failures. Based on the author’s more than thirty years of experience, Practical Plant Failure Analysis: A Guide to Understanding Machinery Deterioration and Improving Equipment Reliability is a down-to-earth guide to improving machinery maintenance and reliability.
Illustrated with hundreds of diagrams and photographs, this book examines…
· When and how to conduct a physical failure analysis
· Basic material properties including heat treating mechanisms, work hardening, and the effects of temperature changes on material properties
· The differences in appearance between ductile overload, brittle overload, and fatigue failures
· High cycle fatigue and how to differentiate between high stress concentrations and high operating stresses
· Low cycle fatigue and unusual fatigue situations
· Lubrication and its influence on the three basic bearing designs
· Ball and roller bearings, gears, fasteners, V-belts, and synchronous belts
Taking a detailed and systematic approach, Practical Plant Failure Analysis thoroughly explains the four major failure mechanisms—wear, corrosion, overload, and fatigue—as well as how to identify them. The author clearly identifies how these mechanisms appear in various components and supplies convenient charts that demonstrate how to identify the specific causes of failure.