汽车可靠性

汽车可靠性

学院：车辆与能源学院

班级：车辆工程卓越试点班

姓名：黄业兴

学号：[1**********]1

指导老师：于悦

Reliability Of Production

Reliability is sometimes simply defined as the probability of a product or process performing its intended or specified or specified function. Inherent in this definition is the implication of performing under certain stated conditions or environments as well as performing for a specified length of time. These stipulations may be qualified with varying degrees of rigidity.

Quality has a little different definition, and it is sometimes defined as "the totality of teat which determine a product's acceptability". Some may choose to define this as conformance to specifications, fitness for use, or meeting requirements the first time. Reliability, as a concept, goes beyond the basic ideas in quality because it adds the concept of the time to the basic definition. That is, reliability may also be viewed as meeting requirements, the first time and every time. Products with reliability will have quality as an attribute.

Many companies have recognized that quality by itself is not sufficient in a competitive world. Products must be built and designed to last a long time in their intended function. This additional requirement goes beyond basic quality and adds a new dimension to marketing for the company. The most successful companies, in terms of product acceptance, have recognized the importance of total life cycle cost and customer satisfaction. A good understanding of reliability is necessary to achieve both with minimum cost in terms of time and resources.

These are three elements that the basis for a reliable product --design, manufacture, and component parts Design is the series of operations involved in taking a product from a conceptual stage to a form that meets both company goals and customer expectations. In addition, this step should include some demonstration that the goals have indeed been met. This is often referred to as the design validation step. Typically, a limited number of key features of the product are demonstrated to meet the goals over the expected life of the product. Reasons for success as well as failure then can be identified early in the product's history and corrected or improved before cost and schedule become big constraints.

Reliability techniques are needed to determine the most appropriate and effective tests as well as reduce the test time, while preserving test conditions. This is known as accelerated testing. Teamwork becomes important here. The object is to finish the design process successfully in as short a time as possible. Bringing other groups into the design validation process will help minimize the number of tests needed later and will reduce duplication.

The text step, manufacturing, involves turning the design into reality without affecting it adversely. Consistency, via such techniques as be tested and demonstrated as being reliable. More than one reliable design has been affected by a process that damaged or weakened one or more of the components or subassemblies. This often

occurs without any one’s knowledge, until a later test or a user of the product identifies the situation.

The third important element involved in producing a reliable design includes the parts and subassemblies that go into the final product. High-quality and consistent parts are needed to preserve the design and be selecting the key parts suppliers ahead of life of the product without some .Supplier who initiated changes in purchased items should be discouraged. In order to prevent such a situation, a clear note—“No change of process without prior notification” is needed on the procurement documents.

Individual attention to the three primary elements of reliability should be coordinated through a reliability plan that makes sense for the type of product and the nature of the industry. This means understanding the marketing goals, such as expected life, and knowing the customers’ expectations and end-use environment.

The reliability function includes estimating conformance to an anticipated life, as well as warranty and failure analysis information. This role establishes the reliability group as a critical interface between many groups. Accordingly, reliability engineers should be skilled in group dynamic as well as the technical aspects of reliability.

When developing a test plan or conducting failure analysis, teamwork become important. Typically, development of the original plan to test the final product involves marketing, design, manufacturing, and product management. A meeting of representatives from all of these functions to discuss a proposed test outline will almost always produce a test plan that meets the design intent and identified customer needs.

Reliability predictions are frequently made for a system or subsystem as part of an ongoing reliability program. These are two basic methods for making these predictions—the parts stress method and the parts count method. The parts stress approach is used for making detailed calculations of a complex system in production. It requires knowledge of the many causes of stress for part. In electronics manufacturing, these might include ambient temperature, junction temperature, voltage, and number of cycles. The parts count method is used primarily in making preliminary predictions for systems where only a limited amount of information is known. It is a mach simpler but less accurate method .

With either method, the idea is to try and predict as accurately as possible the failure rate of a part or system.

One valuable model used by reliability engineers is the so-called bathtub curve, which is named for its particular shape. This curve often describes the reliability of a complex system. The descending slope near the start represents the early history of an item and indicates a decreasing failure rate. It indicates that the first few hours or days of a product’s life are the worst, followed by a period of improvement. This is sometimes referred to as the infant mortality period. For electronic systems, it could

last 5000 hours, or more.

Over time, the failure rate decreases to a low point where it remains essentially constant for a long period. This point of the curve, called the characteristic life or useful life, represents the data entries in reliability prediction tables. Typically, the characteristic life is the constant failure rate period of a product’s life. The last portion of the curve depicts an increasing failure rate and is attributed to wear-out. Not surprisingly, the highest number of failures occur during this period. Properly used, the bathtub curve can also shed valuable light on what to expect when a product or system is ultimately put to the test in the field.

Reliability and quality go hand in hand in a variety of ways. Both are vital in maintaining a competitive position in the world marketplace. It is important to understand the basic concepts and methods for improving product reliability and the ground rules for applying them at all stages of product design and manufacturing.

生产的可靠性

可靠性，有时是简单的定义为概率的一种产品或过程中履行其有意或指定的或指定的功能。固有的这个定义是蕴涵的表演在某些条件或说明，环境以及表演一个指定的时间长度。这些规定，可能是合格的不同程度的刚性。

质量有一个不大的定义不同，它有时被界定为“整体确定产品的认受性” 。有些人可能选择确定，这符合规格，适合使用，或会议的要求，第一时间。可靠性，作为一种概念，超越了基本思路，在质量，因为它增加的概念的时候，基本的定义。这是性，可靠性也可能被视为会议的要求，第一次和每一次。产品的可靠性将有素质作为一项属性。

许多公司已经认识到，质量本身是不足够的，在一个竞争的世界。产品必须建立和设计最后一个长期的时间在他们的功能。这个额外的要求，超越了基本素质，并增加了一个新的层面，以营销为公司。最成功的公司，无论从产品的接受，承认的重要性，全寿命周期成本和客户满意度。一个良好的了解，可靠性是要达到既与最低的成本在条款的时间和资源。

这些都是在三个要素的基础上，为一个可靠的产品-的设计，制造，及零部件的设计是一连串行动，涉及在考虑一个产品从概念阶段的一种形式，能够满足两家公司的目标和客户的期望。此外，这一步骤应包括一些示威的目标，确实得

到了满足。这是经常被称为设计验证步骤。通常情况下，有限数量的关键该产品的特点是体现了以满足目标超过预期寿命的产品。成功的原因，以及失败的，然后才能确定早在产品的历史和纠正或改善之前，成本和时间表，成为大制约因素。

可靠性技术的需要，以确定最适当和有效的测试，以及减少测试时间，同时维护测试条件。这就是所谓的加速试验。团队精神成为这里重要的。目的是完成设计过程中成功地在最短的时间内尽可能。使其他小组到设计验证过程将有助于数目减至最少，测试需要稍后并会减少工作的重复。

文本一步，制造业，涉及把设计变为现实，在不影响它的不利。一致性，透过这样的技术测试和证明，作为可靠的。不止一个可靠的设计已受影响的一个过程，损坏或削弱了一种或一种以上的部件或组件。这往往发生在没有任何一个人的知识，到稍后的测试或用户对产品标识的情况。

第三个重要因素，所涉及的生产了可靠的设计，包括零件及组件即进入最终产品。高品质的和一致的部分是需要维护的设计与被选择的关键零部件供应商未来的生活产品，没有一些。供应商发起的变化，购买的物品，应劝阻。为了防止这种情况下，一个清晰的说明- “没有改变的过程中未经事先通知”是需要就采购文件。

个别注意的三个主要组成部分的可靠性，应通过一个协调计划的可靠性，使意识，为产品的类型和性质的行业。这意味着，了解营销目标，如预期寿命，并了解顾客的期望和最终使用环境。

可靠性功能包括估算符合预期寿命，以及保修和失效分析的资料。这方面的角色确立了可靠性集团作为一个重要的界面之间有很多团体。因此，可靠性工程师应熟练掌握组动态，以及技术方面的可靠性。

当制定一个测试计划或进行故障分析，团队精神成为重要的。通常情况下，发展原来的计划，以测试最终产品，涉及营销，设计，制造，及产品管理。会议的代表来自所有这些功能，讨论拟议的试验大纲将几乎总是产生一个测试计划符合设计意图，并确定了顾客的需求。

可靠性的预测，往往做出一个系统或子系统的一部分，是一项持续的可靠性计划。这是两个基本方法，使这些预言-部分应力法和零件计数方法。部分应力的做法是用于制造详细计算方法一个复杂的系统在生产。它需要知识的原因很

多，应力部分。在电子制造业，这些问题可能包括环境温度，交界处的温度，电压，和数量的周期。部分计数方法是，主要用于在做出初步预测系统，只有有限数量的信息是众所周知的。这是一个简单的马赫，但不太准确的方法。

与任一方法，想法是尝试和预测尽可能准确的故障率的一部份或系统。 一个有价值的模型所使用的可靠性工程师，就是所谓的浴缸曲线，这是命名为其特定的形状。这往往是曲线描述的可靠性，一个复杂的系统。附近的斜坡开始，代表了早期历史的一个项目，并表示减少故障率。它表明，最初几小时或几天内的一个产品的生命是最严重的，其次是一个时期的改善。这是有时被称为婴儿死亡率时期。电子系统，它可以最后五零零零小时，或更多。

随着时间的推移，故障率下降到最低点的地方，它基本上仍是不断的在相当长的时期。这一点的曲线，所谓的特点，生命或有益的生活，代表作品，在数据的可靠性预测表。通常情况下，生活的特点，是不断的不合格率时期，一个产品的生命。最后部分的曲线，描绘了一个增加失败率和原因是磨损。毫不奇怪，人数最高的故障发生在这段期间内。妥善运用，浴缸曲线也可以摆脱了宝贵的光照对什么期望时，一个产品或系统，最终的试验是在外地。

可靠性和质量是相辅相成的，一方面在以各种方式。两者都是非常重要，维持竞争地位，在世界市场的主力军。这是重要的是要了解基本概念和方法，提高产品的可靠性和地面的规则适用于他们的所有阶段的产品设计和制造。